[RFC][PATCH] New message-logging API (kprint) - Kernel

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Thread: [RFC][PATCH] New message-logging API (kprint)

  1. [RFC][PATCH] New message-logging API (kprint)

    Description: This patch largely implements the kprint API as previously
    posted to the LKML and described in Documentation/kprint.txt (see patch).

    The main purpose of this change is provide a unified logging API to the
    kernel and at the same time make it easy to add extensions, now and later.

    My changes and additions are as follows:

    1. A general-purpose ring-buffer data structure. This is used by kprint to
    store the messages, similarly to what printk() does. I've looked, but
    couldn't find something like this in the kernel already.

    2. A generalized printf()-like function (currently called by the somewhat
    confusing name of args_printf). The function, instead of writing to a
    string, calls one of several functions submitted through a struct args_ops.

    This allows us to skip all the characters from the format string and only
    output the characters resulting from argument conversion.

    It should be noted that this function is a generalization of, and largely
    copies, the existing snprintf() function. It would be possible to implement
    snprintf() in terms of the new function if that is preferred.

    3. kprint header and source files. These files implements separating the
    format string from its arguments, and saving them along with extension-
    specific attributes (for example the current time) to the log.

    4. A redefinition of the legacy printk(). The new definition redirects calls
    made from C to the new kprint() system in a mostly backwards-compatible
    way. The incompatibility stems from the fact that kprint() does not return
    the number of characters written to the log. There are several reasons for
    this; firstly, in order to filter out certain log-levels, the actual call
    must happen from within an if-block, and thus no value can be returned.

    5. Changes to calls in the rest of the kernel that expects kprint() to return
    a value. These changes are few and mostly trivial. One of the pitfalls of
    actually using the return value of printk() is that the number is
    unreliable in terms of how much is written to the log, and how much is
    written to the console.

    6. Calling syslog (in glibc, klogctl()) with a (type|0x10) will access the
    new kprint buffer instead of the regular log buffer. The kprint buffer
    is different in that it doesn't record the actual formatted message, but
    the format string and the (formatted) arguments. Example:

    6 0 42949372960000000 arch/um/kernel/mem.c 89 mem_init unknown mem, "Memory: %luk available\x0a", "255104"
    7 0 42949372960000000 init/calibrate.c 135 calibrate_delay unknown calibrate, "Calibrating delay loop... ",
    4 0 42949373260000000 init/calibrate.c 170 calibrate_delay unknown calibrate, "%lu.%02lu BogoMIPS (lpj=%lu)\x0a", "4246" "73" "21233664"
    4 0 42949373260000000 fs/namespace.c 1830 mnt_init unknown namespace, "Mount-cache hash table entries: %d\x0a", "512"
    6 0 42949373260000000 net/socket.c 2116 sock_register unknown socket, "NET: Registered protocol family %d\x0a", "16"
    6 0 42949373300000000 net/socket.c 2116 sock_register unknown socket, "NET: Registered protocol family %d\x0a", "2"

    Each log entry consists of three fields separated by a comma. The first
    field records attributes assigned with the message. In the example above,
    these attributes are, in order, log-level, class, timestamp, source file,
    line in source file, current function, subsystem, and driver/module name.

    The second field contains the format string of the message. This can be
    used to identify a particular string and provide user-space translations of
    the kernel messages.

    The last field contains the arguments to the format string. These arguments
    can be used to reconstruct (i.e. format) a message at a later time,
    possibly with a different format string (i.e. a translation).

    7. The kprint configuration options can be found under General setup
    -> Logging.


    There are also several unresolved issues: (Help would be appreciated!)

    1. As there is not yet a good way to provide compile-time filtering of multi-
    line messages, this feature is completely omitted for now. Note that
    printing multiple related messages, or continuing a single message across
    calls to printk() has always been broken because of the race condition
    that arises when several tasks want to print messages at the same time,
    and at least one of those tasks want to print multiple lines or a
    continuation.

    2. The "new" syslog() doesn't check if the caller has the right privileges.
    To be honest, I don't really know how to do it, apart from looking at what
    do_syslog() currently does.

    3. Certain drivers, like the AIC7xxx SCSI drivers, and a few of the ATM
    drivers rely on the return value of printk(), and consequently will not
    compile. I think this is inherently buggy, but as the code is not always
    trivial to change, the solution for now is to disable these drivers.


    Thank you for reading


    Kind regards,
    Vegard Nossum



    diff --git a/Documentation/kprint.txt b/Documentation/kprint.txt
    new file mode 100644
    index 0000000..3046cbc
    --- /dev/null
    +++ b/Documentation/kprint.txt
    @@ -0,0 +1,238 @@
    +New kernel-message logging API
    +
    +
    +1. Requirements
    +
    + * Backwards compatibility with printk(), syslog(), etc. There is no way the
    +whole kernel can be converted to a new interface in one go. printk() is used
    +all over the kernel, in many different ways, including calls from assembly,
    +multi-line prints spread over several calls, etc.
    +
    + * Extensibility. Features like eliminating messages below a given threshold
    +or recording the location (i.e. source file/line) of a message [1] should be
    +both selectable at compile-time and (if compiled in) at run-time.
    +
    +2. API
    +
    +2.1. linux/kprint.h
    +
    + This header defines the primary (i.e. lowest-level) interface to kprint that
    +is made available to the rest of the kernel.
    +
    +2.1.1. kprint()
    +
    + #define kprint(fmt, ...)
    +
    + This function is the equivalent of the old printk(), except that it does not
    +take a log-level parameter, but emits messages using the default log-level. The
    +string must be a single line of information (i.e. it must not contain any
    +newlines). kprint() is implemented as a macro, and must not be called from
    +assembly.
    +
    +2.1.2. Log-levels
    +
    + To support the different log-levels, there exists one kprint_*() function for
    +each log-level, for example kprint_info(). This contrasts with the printk()
    +interface, but allows the log-level argument to be passed as an argument
    +(instead of prepending it to the message string) and omitted if the default
    +log-level should be used.
    +
    + The string must be a single line of information. Calling
    +kprint_emerg("Oops.") is equivalent to calling printk(KERN_EMERG "Oops.\n").
    +These functions are implemented as macros, and must not be called from
    +assembly. The different log-levels (and their functions) are:
    +
    + enum kprint_loglevel {
    + KPRINT_EMERG, /* kprint_emerg() */
    + KPRINT_ALERT, /* kprint_alert() */
    + KPRINT_CRIT, /* kprint_crit() */
    + KPRINT_ERROR, /* kprint_err() */
    + KPRINT_WARNING, /* kprint_warn() */
    + KPRINT_NOTICE, /* kprint_notice() */
    + KPRINT_INFO, /* kprint_info() */
    + KPRINT_DEBUG, /* kprint_debug() */
    + };
    +
    + The individual log-levels can be enabled/disabled in the kernel configuration
    +and subsequently removed from the kernel (by the compiler) entirely. It is not
    +an option to filter out messages that are simply above a certain log-level,
    +although it could be more convenient; controlling each log-level is the more
    +general approach and can be used to emulate the threshold filter. [8]
    +
    +2.1.3. Classification tags
    +
    + It turns out that many messages share a similar purpose. It would be useful
    +to classify these by a different scheme than severity [6]. Therefore, an
    +additional four special-purpose macros are defined:
    +
    + * printk_detected() A "hardware detected" message
    + * printk_registered() A "device driver (un-)registered" message
    + * printk_setting() A "hardware setting change" message
    + * printk_copyright() A copyright message, such as module authorship
    + information
    +
    + Each message will be assigned the appropriate log-level for the message class
    +in question.
    +
    +2.1.4. Blocks
    +
    + Note: Blocks are not implemented. The details of the API are not yet worked
    + out.
    +
    + In order to print several related lines as one chunk, the emitter should
    +first allocate an object of the type struct kprint_block. This struct is
    +initialized with the function kprint_block_init() which takes as arguments a
    +pointer to an object of the type struct kprint_block followed by the log-level
    +number. The emitter may then make as many or as few calls to kprint_block()
    +that is desired. A final call to kprint_block_flush() appends the messages to
    +the kernel message log in a single, atomic operation. After it has been
    +flushed, the struct is not usable again (unless it is re-initialized). If for
    +any reason the struct should be de-initialized without writing it to the log, a
    +call to kprint_block_abort() must be made.
    +
    +Example: {
    + struct kprint_block out;
    + kprint_block_init(&out, KPRINT_DEBUG);
    + kprint_block(&out, "Stack trace:");
    +
    + while(unwind_stack()) {
    + kprint_block(&out, "%p %s", address, symbol);
    + }
    + kprint_block_flush(&out);
    +}
    +
    +2.1.5. Subsystem/driver tags
    +
    + Many parts of the kernel already prefix their log messages with a subsystem
    +and/or driver tag to identify the source of a particular message. With the
    +kprint interface, these tags are redundant. Instead, the macros SUBSYSTEM and
    +KBUILD_MODNAME are used and recorded along with each log message. Therefore,
    +each source file should define the macro SUBSYSTEM before any of the kprint
    +functions are used. If this macro is not defined, the recorded subsystem will
    +be an empty string. [6][7]
    +
    +2.1.6. Early- and assembly functions
    +
    + It may happen that certain parts of the kernel might wish to emit messages to
    +the log (and console, if any) in an early part of the boot procedure, for
    +example before the main memory allocation routines have been set up properly.
    +For this purpose, a function kprint_early() exists. This "early" is a minimal
    +way for the kernel to log its functions, and may as such not include all the
    +features of the full kprint system. When the kernel is beyond the critical
    +"early" point, the messages (if any) in the "early" log may be moved into the
    +main logging store and kprint_early() must not be used again. kprint_early() is
    +a function and may be called from assembly.
    +
    + To allow non-early calls from assembly, a function kprint_asm() exists. This
    +function takes a log-level number followed by a string literal and a variable
    +number of arguments.
    +
    +2.1.7 Backwards compatibility
    +
    + The legacy printk() function is replaced by a backwards-compatible interface
    +but different implementation. In short, printk should parse messages, remove
    +(and convert) initial log-level tokens, remove any newlines (splitting the
    +string into several lines), and call the appropriate kprint()-system functions.
    +
    + Because printk() itself remains a function with the same specification, all
    +printing/logging mechanisms based on it, such as dev_printk(), sdev_printk(),
    +and ata_dev_printk() will remain functional. Alternatively, the macros could be
    +changed to use the new kprint API.
    +
    +
    +2.2. linux/kprint-light.h
    +
    + The kprint "light" interface provides a simpler interface that covers the
    +most frequent usage patterns. It should be noted that this interface is
    +preferred over the primary interface as it encourages the use of a smaller set
    +of log-levels [5].
    +
    + The interface consists primarily of the three macros, err(), warn(), and
    +info() that emit messages at the corresponding log-level.
    +
    + This header is optional and must not be included by other header files. The
    +names defined by this header are already used by different parts of the kernel,
    +but in different ways. With an optional header, new code (or code converted to
    +the kprint API) can explicitly request these definitions while leaving old
    +locations unchanged.
    +
    +
    +3. Internals
    +
    + Most of the kprint entry-points (especially kprint() and its log-level
    +variations) are implemented as macros in order to be able to transparently pass
    +extra information into the main kprint machinery. This makes the interface
    +abstract, because we can change the behaviour (through the configuration and by
    +adding extensions) without changing the calling code. As an example, prepending
    +the current file and line (the __FILE__ and __LINE__ macros) to the message can
    +be done in such a way that it can be discarded at run-time, or recorded along
    +with (but separate from) the messages. This allows the compiler to completely
    +optimize out calls that are below a certain log-level severity level [2][3].
    +
    + With such a modular interface, message attributes (for example the current
    +time) and arguments can also be recorded separately from the actual format
    +string, instead of written already formatted to a ring buffer of characters.
    +Parameters would be formatted to their own strings (regardless of the original
    +type) and saved in a list.
    +
    +Example: {
    + struct kprint_message {
    + const char *format;
    + struct kprint_arg *args;
    +
    + #ifdef KPRINT_TIMESTAMP
    + unsigned long long timestamp;
    + #endif
    +
    + #ifndef KPRINT_LOCATION
    + const char *file;
    + unsigned int line;
    +
    + const char *function;
    + #endif
    + };
    +
    + struct kprint_arg {
    + struct kprint_arg *next;
    +
    + /* The string formatted argument, regardless
    + * of original type. */
    + char *arg;
    + };
    +}
    +
    + This can be a great help, for example in (user-space) localisation of kernel
    +messages [4], since the "static" message (ie. format string) can be translated
    +separately and the arguments re-attached at run-time, possibly in a different
    +order. A new kernel-/user-space interface would be needed to retrieve the
    +messages in this format, though the syslog() and /proc/kmsg interfaces will
    +retain backwards compatibility by formatting messages as they are requested
    +from user-space.
    +
    + This does not mean that user-space is obliged provide any form of
    +lookup-/translation tables in order to read the kernel log; the kernel simply
    +hands over the format string used to format a particular message in addition to
    +the full log message, and this format string may be used to easily look up
    +translations (if they exist).
    +
    +4. Considerations
    +
    + This scheme is obviously much more complex than the printk() is today. But at
    +the same time, it is also much more powerful, extensible, and clearly/cleanly
    +defined.
    +
    + The kernel can still used a fixed-size ring-buffer for storing the kernel
    +log. With a fixed, static buffer, we are certain to never run into memory-
    +related problems, even if the rest of the system is unstable or unusable.
    +
    +
    +References
    +
    +[1] http://lkml.org/lkml/2007/9/21/267 (Joe Perches)
    +[2] http://lkml.org/lkml/2007/9/20/352 (Rob Landley)
    +[3] http://lkml.org/lkml/2007/9/21/151 (Dick Streefland)
    +[4] http://lkml.org/lkml/2007/6/13/146 (Michael Holzheu)
    +[5] http://lkml.org/lkml/2007/9/24/320 (Jesse Barnes)
    +[6] http://lkml.org/lkml/2007/9/22/162 (Miguel Ojeda)
    +[7] http://lkml.org/lkml/2007/9/25/62 (Vegard Nossum)
    +[8] http://lkml.org/lkml/2007/9/22/157 (Joe Perches)
    diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
    index 47b0bef..70eda51 100644
    --- a/arch/i386/kernel/traps.c
    +++ b/arch/i386/kernel/traps.c
    @@ -198,7 +198,7 @@ EXPORT_SYMBOL(dump_trace);
    static void
    print_trace_warning_symbol(void *data, char *msg, unsigned long symbol)
    {
    - printk(data);
    + printk("%s", data);
    print_symbol(msg, symbol);
    printk("\n");
    }
    diff --git a/arch/um/include/user.h b/arch/um/include/user.h
    index d380e6d..c971d93 100644
    --- a/arch/um/include/user.h
    +++ b/arch/um/include/user.h
    @@ -19,9 +19,11 @@
    */
    #include

    -extern void panic(const char *fmt, ...)
    +extern int printk_asm(const char *fmt, ...)
    __attribute__ ((format (printf, 1, 2)));
    -extern int printk(const char *fmt, ...)
    +#define printk printk_asm
    +
    +extern void panic(const char *fmt, ...)
    __attribute__ ((format (printf, 1, 2)));
    extern void schedule(void);
    extern int in_aton(char *str);
    diff --git a/crypto/tcrypt.c b/crypto/tcrypt.c
    index 11f9359..acdfc45 100644
    --- a/crypto/tcrypt.c
    +++ b/crypto/tcrypt.c
    @@ -874,9 +874,8 @@ static void test_available(void)
    char **name = check;

    while (*name) {
    - printk("alg %s ", *name);
    - printk(crypto_has_alg(*name, 0, 0) ?
    - "found\n" : "not found\n");
    + printk("algorithm %s %s\n", *name, crypto_has_alg(*name, 0, 0)
    + ? "found" : "not found");
    name++;
    }
    }
    diff --git a/drivers/char/mem.c b/drivers/char/mem.c
    index bbee97f..83bd492 100644
    --- a/drivers/char/mem.c
    +++ b/drivers/char/mem.c
    @@ -890,10 +890,12 @@ static ssize_t kmsg_write(struct file * file, const char __user * buf,
    ret = -EFAULT;
    if (!copy_from_user(tmp, buf, count)) {
    tmp[count] = 0;
    - ret = printk("%s", tmp);
    - if (ret > count)
    - /* printk can add a prefix */
    - ret = count;
    + printk("%s", tmp);
    +
    + /* Instead of saying how many bytes were written to the log,
    + * including log-level, timestamp, etc., we simply return the
    + * string length. */
    + ret = strlen(tmp);
    }
    kfree(tmp);
    return ret;
    diff --git a/drivers/ide/ide-lib.c b/drivers/ide/ide-lib.c
    index 92a6c7b..5f3061f 100644
    --- a/drivers/ide/ide-lib.c
    +++ b/drivers/ide/ide-lib.c
    @@ -447,7 +447,8 @@ static u8 ide_dump_ata_status(ide_drive_t *drive, const char *msg, u8 stat)
    printk("%s: %s: error=0x%02x { ", drive->name, msg, err);
    if (err & ABRT_ERR) printk("DriveStatusError ");
    if (err & ICRC_ERR)
    - printk((err & ABRT_ERR) ? "BadCRC " : "BadSector ");
    + printk("%s", (err & ABRT_ERR)
    + ? "BadCRC " : "BadSector ");
    if (err & ECC_ERR) printk("UncorrectableError ");
    if (err & ID_ERR) printk("SectorIdNotFound ");
    if (err & TRK0_ERR) printk("TrackZeroNotFound ");
    diff --git a/drivers/md/md.c b/drivers/md/md.c
    index f883b7e..a04cbcf 100644
    --- a/drivers/md/md.c
    +++ b/drivers/md/md.c
    @@ -62,7 +62,10 @@
    #define MdpMinorShift 6

    #define DEBUG 0
    -#define dprintk(x...) ((void)(DEBUG && printk(x)))
    +#define dprintk(x...) \
    + if(DEBUG) { \
    + printk(x); \
    + }


    #ifndef MODULE
    diff --git a/drivers/media/dvb/frontends/tda10021.c b/drivers/media/dvb/frontends/tda10021.c
    index e725f61..c564f64 100644
    --- a/drivers/media/dvb/frontends/tda10021.c
    +++ b/drivers/media/dvb/frontends/tda10021.c
    @@ -351,10 +351,15 @@ static int tda10021_get_frontend(struct dvb_frontend* fe, struct dvb_frontend_pa
    afc = tda10021_readreg(state, 0x19);
    if (verbose) {
    /* AFC only valid when carrier has been recovered */
    - printk(sync & 2 ? "DVB: TDA10021(%d): AFC (%d) %dHz\n" :
    - "DVB: TDA10021(%d): [AFC (%d) %dHz]\n",
    - state->frontend.dvb->num, afc,
    - -((s32)p->u.qam.symbol_rate * afc) >> 10);
    + if(sync & 2) {
    + printk("DVB: TDA10021(%d): AFC (%d) %dHz\n",
    + state->frontend.dvb->num, afc,
    + -((s32)p->u.qam.symbol_rate * afc) >> 10);
    + } else {
    + printk("DVB: TDA10021(%d): [AFC (%d) %dHz]\n",
    + state->frontend.dvb->num, afc,
    + -((s32)p->u.qam.symbol_rate * afc) >> 10);;
    + }
    }

    p->inversion = ((state->reg0 & 0x20) == 0x20) ^ (state->config->invert != 0) ? INVERSION_ON : INVERSION_OFF;
    diff --git a/drivers/media/dvb/frontends/tda10023.c b/drivers/media/dvb/frontends/tda10023.c
    index 4bb06f9..c3c6e23 100644
    --- a/drivers/media/dvb/frontends/tda10023.c
    +++ b/drivers/media/dvb/frontends/tda10023.c
    @@ -414,10 +414,15 @@ static int tda10023_get_frontend(struct dvb_frontend* fe, struct dvb_frontend_pa

    if (verbose) {
    /* AFC only valid when carrier has been recovered */
    - printk(sync & 2 ? "DVB: TDA10023(%d): AFC (%d) %dHz\n" :
    - "DVB: TDA10023(%d): [AFC (%d) %dHz]\n",
    - state->frontend.dvb->num, afc,
    - -((s32)p->u.qam.symbol_rate * afc) >> 10);
    + if(sync & 2) {
    + printk("DVB: TDA10023(%d): AFC (%d) %dHz\n",
    + state->frontend.dvb->num, afc,
    + -((s32)p->u.qam.symbol_rate * afc) >> 10);
    + } else {
    + printk("DVB: TDA10023(%d): [AFC (%d) %dHz]\n",
    + state->frontend.dvb->num, afc,
    + -((s32)p->u.qam.symbol_rate * afc) >> 10);
    + }
    }

    p->inversion = (inv&0x20?0:1);
    diff --git a/drivers/media/dvb/frontends/ves1820.c b/drivers/media/dvb/frontends/ves1820.c
    index 9b57576..e9af469 100644
    --- a/drivers/media/dvb/frontends/ves1820.c
    +++ b/drivers/media/dvb/frontends/ves1820.c
    @@ -319,8 +319,13 @@ static int ves1820_get_frontend(struct dvb_frontend* fe, struct dvb_frontend_par
    afc = ves1820_readreg(state, 0x19);
    if (verbose) {
    /* AFC only valid when carrier has been recovered */
    - printk(sync & 2 ? "ves1820: AFC (%d) %dHz\n" :
    - "ves1820: [AFC (%d) %dHz]\n", afc, -((s32) p->u.qam.symbol_rate * afc) >> 10);
    + if(sync & 2) {
    + printk("ves1820: AFC (%d) %dHz\n", afc,
    + -((s32) p->u.qam.symbol_rate * afc) >> 10);
    + } else {
    + printk("ves1820: [AFC (%d) %dHz]\n", afc,
    + -((s32) p->u.qam.symbol_rate * afc) >> 10);
    + }
    }

    if (!state->config->invert) {
    diff --git a/drivers/media/video/em28xx/em28xx-core.c b/drivers/media/video/em28xx/em28xx-core.c
    index 255a47d..5a1f398 100644
    --- a/drivers/media/video/em28xx/em28xx-core.c
    +++ b/drivers/media/video/em28xx/em28xx-core.c
    @@ -148,8 +148,12 @@ int em28xx_read_reg_req_len(struct em28xx *dev, u8 req, u16 reg,
    USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
    0x0000, reg, buf, len, HZ);

    - if (reg_debug){
    - printk(ret < 0 ? " failed!\n" : "%02x values: ", ret);
    + if (reg_debug) {
    + if(ret < 0)
    + printk(" failed!\n");
    + else
    + printk("%02x values: ", ret);
    +
    for (byte = 0; byte < len; byte++) {
    printk(" %02x", buf[byte]);
    }
    @@ -177,8 +181,12 @@ int em28xx_read_reg_req(struct em28xx *dev, u8 req, u16 reg)
    USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
    0x0000, reg, &val, 1, HZ);

    - if (reg_debug)
    - printk(ret < 0 ? " failed!\n" : "%02x\n", val);
    + if (reg_debug) {
    + if(ret < 0)
    + printk(" failed!\n");
    + else
    + printk("%02x\n", val);
    + }

    if (ret < 0)
    return ret;
    diff --git a/drivers/media/video/usbvideo/usbvideo.h b/drivers/media/video/usbvideo/usbvideo.h
    index 051775d..39fdadc 100644
    --- a/drivers/media/video/usbvideo/usbvideo.h
    +++ b/drivers/media/video/usbvideo/usbvideo.h
    @@ -22,7 +22,12 @@
    #include

    /* Most helpful debugging aid */
    -#define assert(expr) ((void) ((expr) ? 0 : (err("assert failed at line %d",__LINE__))))
    +#define assert(expr) \
    + do { \
    + if(!(expr)) { \
    + err("assert failed at line %d", __LINE__); \
    + } \
    + } while(0)

    #define USBVIDEO_REPORT_STATS 1 /* Set to 0 to block statistics on close */

    diff --git a/drivers/net/e100.c b/drivers/net/e100.c
    index 280313b..b4a7dbc 100644
    --- a/drivers/net/e100.c
    +++ b/drivers/net/e100.c
    @@ -182,9 +182,13 @@ MODULE_PARM_DESC(debug, "Debug level (0=none,...,16=all)");
    MODULE_PARM_DESC(eeprom_bad_csum_allow, "Allow bad eeprom checksums");
    MODULE_PARM_DESC(use_io, "Force use of i/o access mode");
    #define DPRINTK(nlevel, klevel, fmt, args...) \
    - (void)((NETIF_MSG_##nlevel & nic->msg_enable) && \
    - printk(KERN_##klevel PFX "%s: %s: " fmt, nic->netdev->name, \
    - __FUNCTION__ , ## args))
    + do { \
    + if(NETIF_MSG_##nlevel & nic->msg_enable) { \
    + printk(KERN_##klevel PFX "%s: %s: " fmt, \
    + nic->netdev->name, \
    + __FUNCTION__ , ## args); \
    + } \
    + } while(0)

    #define INTEL_8255X_ETHERNET_DEVICE(device_id, ich) {\
    PCI_VENDOR_ID_INTEL, device_id, PCI_ANY_ID, PCI_ANY_ID, \
    diff --git a/drivers/net/e1000/e1000.h b/drivers/net/e1000/e1000.h
    index 16a6edf..5445616 100644
    --- a/drivers/net/e1000/e1000.h
    +++ b/drivers/net/e1000/e1000.h
    @@ -90,10 +90,14 @@ struct e1000_adapter;
    #define E1000_ERR(args...) printk(KERN_ERR "e1000: " args)

    #define PFX "e1000: "
    -#define DPRINTK(nlevel, klevel, fmt, args...) \
    - (void)((NETIF_MSG_##nlevel & adapter->msg_enable) && \
    - printk(KERN_##klevel PFX "%s: %s: " fmt, adapter->netdev->name, \
    - __FUNCTION__ , ## args))
    +#define DPRINTK(nlevel, klevel, fmt, args...) \
    + do { \
    + if(NETIF_MSG_##nlevel & adapter->msg_enable) { \
    + printk(KERN_##klevel PFX "%s: %s: " fmt, \
    + adapter->netdev->name, __FUNCTION__, \
    + ## args); \
    + } \
    + } while(0)

    #define E1000_MAX_INTR 10

    diff --git a/drivers/net/irda/ma600.c b/drivers/net/irda/ma600.c
    index f5e6836..bd59424 100644
    --- a/drivers/net/irda/ma600.c
    +++ b/drivers/net/irda/ma600.c
    @@ -44,7 +44,10 @@

    #ifndef NDEBUG
    #undef IRDA_DEBUG
    - #define IRDA_DEBUG(n, args...) (printk(KERN_DEBUG args))
    + #define IRDA_DEBUG(n, args...) \
    + do { \
    + printk(KERN_DEBUG args); \
    + } while(0)

    #undef ASSERT
    #define ASSERT(expr, func) \
    diff --git a/drivers/net/ixgb/ixgb.h b/drivers/net/ixgb/ixgb.h
    index 3569d5b..f40502b 100644
    --- a/drivers/net/ixgb/ixgb.h
    +++ b/drivers/net/ixgb/ixgb.h
    @@ -82,10 +82,13 @@ struct ixgb_adapter;
    #endif

    #define PFX "ixgb: "
    -#define DPRINTK(nlevel, klevel, fmt, args...) \
    - (void)((NETIF_MSG_##nlevel & adapter->msg_enable) && \
    - printk(KERN_##klevel PFX "%s: %s: " fmt, adapter->netdev->name, \
    - __FUNCTION__ , ## args))
    +#define DPRINTK(nlevel, klevel, fmt, args...) \
    + do { \
    + if(NETIF_MSG_##nlevel & adapter->msg_enable) { \
    + printk(KERN_##klevel PFX "%s: %s: " fmt, \
    + adapter->netdev->name, __FUNCTION__, ## args); \
    + } \
    + } while(0)


    /* TX/RX descriptor defines */
    diff --git a/drivers/net/lib8390.c b/drivers/net/lib8390.c
    index c429a50..d2e2238 100644
    --- a/drivers/net/lib8390.c
    +++ b/drivers/net/lib8390.c
    @@ -1,4 +1,3 @@
    -/* 8390.c: A general NS8390 ethernet driver core for linux. */
    /*
    Written 1992-94 by Donald Becker.

    @@ -451,11 +450,17 @@ static irqreturn_t __ei_interrupt(int irq, void *dev_id)
    {
    #if 1 /* This might just be an interrupt for a PCI device sharing this line */
    /* The "irqlock" check is only for testing. */
    - printk(ei_local->irqlock
    - ? "%s: Interrupted while interrupts are masked! isr=%#2x imr=%#2x.\n"
    - : "%s: Reentering the interrupt handler! isr=%#2x imr=%#2x.\n",
    - dev->name, ei_inb_p(e8390_base + EN0_ISR),
    - ei_inb_p(e8390_base + EN0_IMR));
    + if(ei_local->irqlock) {
    + printk("%s: Interrupted while interrupts are masked! "
    + "isr=%#2x imr=%#2x.\n",
    + dev->name, ei_inb_p(e8390_base + EN0_ISR),
    + ei_inb_p(e8390_base + EN0_IMR));
    + } else {
    + printk("%s: Reentering the interrupt handler! "
    + "isr=%#2x imr=%#2x.\n",
    + dev->name, ei_inb_p(e8390_base + EN0_ISR),
    + ei_inb_p(e8390_base + EN0_IMR));
    + }
    #endif
    spin_unlock(&ei_local->page_lock);
    return IRQ_NONE;
    diff --git a/drivers/net/pcmcia/axnet_cs.c b/drivers/net/pcmcia/axnet_cs.c
    index 50dff1b..8051b5c 100644
    --- a/drivers/net/pcmcia/axnet_cs.c
    +++ b/drivers/net/pcmcia/axnet_cs.c
    @@ -1213,11 +1213,17 @@ static irqreturn_t ax_interrupt(int irq, void *dev_id)
    {
    #if 1 /* This might just be an interrupt for a PCI device sharing this line */
    /* The "irqlock" check is only for testing. */
    - printk(ei_local->irqlock
    - ? "%s: Interrupted while interrupts are masked! isr=%#2x imr=%#2x.\n"
    - : "%s: Reentering the interrupt handler! isr=%#2x imr=%#2x.\n",
    + if(ei_local->irqlock) {
    + printk("%s: Interrupted while interrupts are masked! "
    + " isr=%#2x imr=%#2x.\n",
    dev->name, inb_p(e8390_base + EN0_ISR),
    inb_p(e8390_base + EN0_IMR));
    + } else {
    + printk("%s: Reentering the interrupt handler! "
    + "isr=%#2x imr=%#2x.\n",
    + dev->name, inb_p(e8390_base + EN0_ISR),
    + inb_p(e8390_base + EN0_IMR));
    + }
    #endif
    spin_unlock(&ei_local->page_lock);
    return IRQ_NONE;
    diff --git a/drivers/pcmcia/rsrc_nonstatic.c b/drivers/pcmcia/rsrc_nonstatic.c
    index bfcaad6..d90ebb6 100644
    --- a/drivers/pcmcia/rsrc_nonstatic.c
    +++ b/drivers/pcmcia/rsrc_nonstatic.c
    @@ -248,7 +248,10 @@ static void do_io_probe(struct pcmcia_socket *s, kio_addr_t base, kio_addr_t num
    }
    }

    - printk(any ? "\n" : " clean.\n");
    + if(any)
    + printk("\n");
    + else
    + printk(" clean.\n");
    }
    #endif

    @@ -396,7 +399,10 @@ static int do_mem_probe(u_long base, u_long num, struct pcmcia_socket *s)
    bad += j-i;
    }
    }
    - printk(bad ? "\n" : " clean.\n");
    + if(bad)
    + printk("\n");
    + else
    + printk(" clean.\n");
    return (num - bad);
    }

    diff --git a/drivers/scsi/advansys.c b/drivers/scsi/advansys.c
    index 79c0b6e..712bf9f 100644
    --- a/drivers/scsi/advansys.c
    +++ b/drivers/scsi/advansys.c
    @@ -7417,7 +7417,7 @@ static int asc_prt_line(char *buf, int buflen, char *fmt, ...)
    ret = vsprintf(s, fmt, args);
    ASC_ASSERT(ret < ASC_PRTLINE_SIZE);
    if (buf == NULL) {
    - (void)printk(s);
    + printk(s);
    ret = 0;
    } else {
    ret = min(buflen, ret);
    diff --git a/include/asm-generic/pgtable-nopmd.h b/include/asm-generic/pgtable-nopmd.h
    index 29ff5d8..3f9e8d8 100644
    --- a/include/asm-generic/pgtable-nopmd.h
    +++ b/include/asm-generic/pgtable-nopmd.h
    @@ -28,7 +28,10 @@ static inline int pud_none(pud_t pud) { return 0; }
    static inline int pud_bad(pud_t pud) { return 0; }
    static inline int pud_present(pud_t pud) { return 1; }
    static inline void pud_clear(pud_t *pud) { }
    -#define pmd_ERROR(pmd) (pud_ERROR((pmd).pud))
    +#define pmd_ERROR(pmd) \
    + do { \
    + pud_ERROR((pmd).pud); \
    + } while(0)

    #define pud_populate(mm, pmd, pte) do { } while (0)

    diff --git a/include/asm-generic/pgtable-nopud.h b/include/asm-generic/pgtable-nopud.h
    index 5664645..b091db1 100644
    --- a/include/asm-generic/pgtable-nopud.h
    +++ b/include/asm-generic/pgtable-nopud.h
    @@ -26,7 +26,10 @@ static inline int pgd_none(pgd_t pgd) { return 0; }
    static inline int pgd_bad(pgd_t pgd) { return 0; }
    static inline int pgd_present(pgd_t pgd) { return 1; }
    static inline void pgd_clear(pgd_t *pgd) { }
    -#define pud_ERROR(pud) (pgd_ERROR((pud).pgd))
    +#define pud_ERROR(pud) \
    + do { \
    + pgd_ERROR((pud).pgd); \
    + } while(0)

    #define pgd_populate(mm, pgd, pud) do { } while (0)
    /*
    diff --git a/include/linux/args.h b/include/linux/args.h
    new file mode 100644
    index 0000000..7ad1e02
    --- /dev/null
    +++ b/include/linux/args.h
    @@ -0,0 +1,29 @@
    +/*
    + * Copyright (C) 2007 Vegard Nossum
    + */
    +
    +#ifndef LINUX_ARGS_H
    +#define LINUX_ARGS_H
    +
    +#include
    +
    +struct args_ops {
    + void (*begin)(void *data);
    + void (*end)(void *data);
    + void (*put_format)(void *data, char c);
    +
    + void (*begin_param)(void *data);
    + void (*end_param)(void *data);
    + void (*put_param)(void *data, char c);
    +
    + void (*unknown_conversion)(void *data, char c);
    +};
    +
    +extern void args_printf(void *data, const struct args_ops *ops,
    + const char *fmt, ...)
    + __attribute__ ((format (printf, 3, 4)));
    +extern void args_vprintf(void *data, const struct args_ops *ops,
    + const char *fmt, va_list args)
    + __attribute__ ((format (printf, 3, 0)));
    +
    +#endif
    diff --git a/include/linux/kernel.h b/include/linux/kernel.h
    index 47160fe..f014b7c 100644
    --- a/include/linux/kernel.h
    +++ b/include/linux/kernel.h
    @@ -14,6 +14,7 @@
    #include
    #include
    #include
    +#include
    #include
    #include

    @@ -155,15 +156,35 @@ extern void dump_thread(struct pt_regs *regs, struct user *dump);
    #ifdef CONFIG_PRINTK
    asmlinkage int vprintk(const char *fmt, va_list args)
    __attribute__ ((format (printf, 1, 0)));
    -asmlinkage int printk(const char * fmt, ...)
    +asmlinkage int printk_asm(const char * fmt, ...)
    __attribute__ ((format (printf, 1, 2))) __cold;
    #else
    static inline int vprintk(const char *s, va_list args)
    __attribute__ ((format (printf, 1, 0)));
    static inline int vprintk(const char *s, va_list args) { return 0; }
    -static inline int printk(const char *s, ...)
    +static inline int printk_asm(const char *s, ...)
    __attribute__ ((format (printf, 1, 2)));
    -static inline int __cold printk(const char *s, ...) { return 0; }
    +static inline int __cold printk_asm(const char *s, ...) { return 0; }
    +#endif
    +
    +#ifdef __ASSEMBLY__
    +/* Redirect printk() to a backwards-compatible kprint. */
    +#define printk kprint_asm
    +#endif
    +
    +#ifndef __ASSEMBLY__
    +/* Redirect printk() to kprint. */
    +#define printk(fmt, ...) \
    + do { \
    + if(fmt[0] == '<' && fmt[1] >= '0' && \
    + fmt[1] <= '9' && fmt[2] == '>') \
    + { \
    + kprint_wrapper(fmt[1] - '0', KPRINT_NO_CLASS, \
    + fmt, ## __VA_ARGS__); \
    + } else { \
    + kprint(fmt, ## __VA_ARGS__); \
    + } \
    + } while(0)
    #endif

    unsigned long int_sqrt(unsigned long);
    diff --git a/include/linux/kprint-light.h b/include/linux/kprint-light.h
    new file mode 100644
    index 0000000..f51ce71
    --- /dev/null
    +++ b/include/linux/kprint-light.h
    @@ -0,0 +1,25 @@
    +/*
    + * Message-logging API
    + * Copyright (C) 2007 Vegard Nossum
    + */
    +
    +/**
    + * Do not include this header from other headers! (i.e. Don't enforce these
    + * definitions on anybody, since they're fairly common names.)
    + */
    +
    +#ifndef LINUX_KPRINT_LIGHT_H
    +#define LINUX_KPRINT_LIGHT_H
    +
    +#include
    +
    +#define err(fmt, ...) \
    + kprint_err(fmt, ## __VA_ARGS__)
    +
    +#define warn(fmt, ...) \
    + kprint_warn(fmt, ## __VA_ARGS__)
    +
    +#define info(fmt, ...) \
    + kprint_info(fmt, ## __VA_ARGS__)
    +
    +#endif
    diff --git a/include/linux/kprint.h b/include/linux/kprint.h
    new file mode 100644
    index 0000000..27aff06
    --- /dev/null
    +++ b/include/linux/kprint.h
    @@ -0,0 +1,201 @@
    +/*
    + * Message-logging API
    + * Copyright (C) 2007 Vegard Nossum
    + */
    +
    +#ifndef LINUX_KPRINT_H
    +#define LINUX_KPRINT_H
    +
    +#include
    +
    +enum kprint_loglevel {
    + KPRINT_EMERG,
    + KPRINT_ALERT,
    + KPRINT_CRIT,
    + KPRINT_ERROR,
    + KPRINT_WARNING,
    + KPRINT_NOTICE,
    + KPRINT_INFO,
    + KPRINT_DEBUG,
    +};
    +
    +/* We really need numeric values for these. */
    +#ifndef CONFIG_KPRINT_FILTER_EMERG
    +#define CONFIG_KPRINT_FILTER_EMERG 0
    +#endif
    +
    +#ifndef CONFIG_KPRINT_FILTER_ALERT
    +#define CONFIG_KPRINT_FILTER_ALERT 0
    +#endif
    +
    +#ifndef CONFIG_KPRINT_FILTER_CRIT
    +#define CONFIG_KPRINT_FILTER_CRIT 0
    +#endif
    +
    +#ifndef CONFIG_KPRINT_FILTER_ERROR
    +#define CONFIG_KPRINT_FILTER_ERROR 0
    +#endif
    +
    +#ifndef CONFIG_KPRINT_FILTER_WARNING
    +#define CONFIG_KPRINT_FILTER_WARNING 0
    +#endif
    +
    +#ifndef CONFIG_KPRINT_FILTER_NOTICE
    +#define CONFIG_KPRINT_FILTER_NOTICE 0
    +#endif
    +
    +#ifndef CONFIG_KPRINT_FILTER_INFO
    +#define CONFIG_KPRINT_FILTER_INFO 0
    +#endif
    +
    +#ifndef CONFIG_KPRINT_FILTER_DEBUG
    +#define CONFIG_KPRINT_FILTER_DEBUG 0
    +#endif
    +
    +enum kprint_class {
    + KPRINT_NO_CLASS,
    + KPRINT_DETECTED,
    + KPRINT_REGISTERED,
    + KPRINT_SETTING,
    + KPRINT_COPYRIGHT,
    +};
    +
    +#ifdef CONFIG_KPRINT_TIMESTAMP
    +/* XXX: This is ugly. */
    +unsigned long long kprint_clock(void);
    +#endif
    +
    +#ifdef CONFIG_KPRINT_TAGS
    +/* Default (fall-back) values for subsystem/driver tags. If tags are not
    + * enabled, these symbols will never be referenced. */
    +static const char *KPRINT_SUBSYSTEM __maybe_unused = "unknown";
    +static const char *KPRINT_DRIVER __maybe_unused = KBUILD_MODNAME;
    +#endif
    +
    +/* Define conditional macros that are used to optimize out structure fields,
    + * function parameters, etc. at compile time. */
    +#ifdef CONFIG_KPRINT_CLASS
    +#define KPRINT_CLASS(x...) x
    +#else
    +#define KPRINT_CLASS(x...)
    +#endif
    +
    +#ifdef CONFIG_KPRINT_TIMESTAMP
    +#define KPRINT_TIMESTAMP(x...) x
    +#else
    +#define KPRINT_TIMESTAMP(x...)
    +#endif
    +
    +#ifdef CONFIG_KPRINT_LOCATION
    +#define KPRINT_LOCATION(x...) x
    +#else
    +#define KPRINT_LOCATION(x...)
    +#endif
    +
    +#ifdef CONFIG_KPRINT_TAGS
    +#define KPRINT_TAGS(x...) x
    +#else
    +#define KPRINT_TAGS(x...)
    +#endif
    +
    +/* A single argument, formatted as a string. */
    +struct kprint_arg {
    + struct kprint_arg *next;
    + char *arg;
    +};
    +
    +struct kprint_message {
    + enum kprint_loglevel loglevel;
    +
    + KPRINT_CLASS(enum kprint_class class);
    + KPRINT_TIMESTAMP(unsigned long long clock);
    + KPRINT_LOCATION(const char *file);
    + KPRINT_LOCATION(unsigned int line);
    + KPRINT_LOCATION(const char *function);
    + KPRINT_TAGS(const char *subsystem);
    + KPRINT_TAGS(const char *module);
    +
    + const char *format;
    + struct kprint_arg *args;
    +};
    +
    +void kprint_function(
    + enum kprint_loglevel loglevel,
    + KPRINT_CLASS(enum kprint_class class,)
    + KPRINT_TIMESTAMP(unsigned long long clock,)
    + KPRINT_LOCATION(const char *file,)
    + KPRINT_LOCATION(unsigned int line,)
    + KPRINT_LOCATION(const char *function,)
    + KPRINT_TAGS(const char *subsystem,)
    + KPRINT_TAGS(const char *module,)
    + const char *format, ...);
    +
    +/* Thank god for constant expression evaluation. This returns true if the
    + * message should be filtered out. */
    +#define KPRINT_FILTER(level) \
    + (CONFIG_KPRINT_FILTER_EMERG && (level) == KPRINT_EMERG) \
    + || (CONFIG_KPRINT_FILTER_ALERT && (level) == KPRINT_ALERT) \
    + || (CONFIG_KPRINT_FILTER_CRIT && (level) == KPRINT_CRIT) \
    + || (CONFIG_KPRINT_FILTER_ERROR && (level) == KPRINT_ERROR) \
    + || (CONFIG_KPRINT_FILTER_WARNING && (level) == KPRINT_WARNING) \
    + || (CONFIG_KPRINT_FILTER_NOTICE && (level) == KPRINT_NOTICE) \
    + || (CONFIG_KPRINT_FILTER_INFO && (level) == KPRINT_INFO) \
    + || (CONFIG_KPRINT_FILTER_DEBUG && (level) == KPRINT_DEBUG)
    +
    +#define kprint_wrapper(level, class, fmt, ...) \
    + if (!(KPRINT_FILTER(level))) { \
    + kprint_function( \
    + level, \
    + KPRINT_CLASS(class,) \
    + KPRINT_TIMESTAMP(kprint_clock(),) \
    + KPRINT_LOCATION(__FILE__,) \
    + KPRINT_LOCATION(__LINE__,) \
    + KPRINT_LOCATION(__FUNCTION__,) \
    + KPRINT_TAGS(KPRINT_SUBSYSTEM,) \
    + KPRINT_TAGS(KPRINT_DRIVER,) \
    + fmt, ## __VA_ARGS__); \
    + }
    +
    +/* Severity levels */
    +#define kprint(fmt, ...) \
    + kprint_wrapper(KPRINT_WARNING, KPRINT_NO_CLASS, fmt, ## __VA_ARGS__)
    +
    +#define kprint_emerg(fmt, ...) \
    + kprint_wrapper(KPRINT_EMERG, KPRINT_NO_CLASS, fmt, ## __VA_ARGS__)
    +
    +#define kprint_alert(fmt, ...) \
    + kprint_wrapper(KPRINT_ALERT, KPRINT_NO_CLASS, fmt, ## __VA_ARGS__)
    +
    +#define kprint_crit(fmt, ...) \
    + kprint_wrapper(KPRINT_CRIT, KPRINT_NO_CLASS, fmt, ## __VA_ARGS__)
    +
    +#define kprint_err(fmt, ...) \
    + kprint_wrapper(KPRINT_ERROR, KPRINT_NO_CLASS, fmt, ## __VA_ARGS__)
    +
    +#define kprint_warn(fmt, ...) \
    + kprint_wrapper(KPRINT_WARNING, KPRINT_NO_CLASS, fmt, ## __VA_ARGS__)
    +
    +#define kprint_notice(fmt, ...) \
    + kprint_wrapper(KPRINT_NOTICE, KPRINT_NO_CLASS, fmt, ## __VA_ARGS__)
    +
    +#define kprint_info(fmt, ...) \
    + kprint_wrapper(KPRINT_INFO, KPRINT_NO_CLASS, fmt, ## __VA_ARGS__)
    +
    +#define kprint_debug(fmt, ...) \
    + kprint_wrapper(KPRINT_DEBUG, KPRINT_NO_CLASS, fmt, ## __VA_ARGS__)
    +
    +
    +/* Classification tags */
    +#define kprint_detected(fmt, ...) \
    + kprint_wrapper(KPRINT_INFO, KPRINT_DETECTED, fmt, ## __VA_ARGS__)
    +
    +#define kprint_registered(fmt, ...) \
    + kprint_wrapper(KPRINT_INFO, KPRINT_REGISTERED, fmt, ## __VA_ARGS__)
    +
    +#define kprint_setting(fmt, ...) \
    + kprint_wrapper(KPRINT_INFO, KPRINT_SETTING, fmt, ## __VA_ARGS__)
    +
    +#define kprint_copyright(fmt, ...) \
    + kprint_wrapper(KPRINT_INFO, KPRINT_COPYRIGHT, fmt, ## __VA_ARGS__)
    +
    +#endif
    diff --git a/include/linux/ringbuffer.h b/include/linux/ringbuffer.h
    new file mode 100644
    index 0000000..814bbe5
    --- /dev/null
    +++ b/include/linux/ringbuffer.h
    @@ -0,0 +1,34 @@
    +/*
    + * General-purpose ring-buffer data structure
    + * Copyright (C) 2007 Vegard Nossum
    + */
    +
    +#ifndef LINUX_RINGBUFFER_H
    +#define LINUX_RINGBUFFER_H
    +
    +#include
    +
    +struct ringbuffer {
    + char *data;
    + unsigned int size;
    + unsigned int mask;
    +
    + unsigned int wr;
    + unsigned int rd;
    +
    + unsigned int fill_count;
    +};
    +
    +void ringbuffer_init(struct ringbuffer *rb, char *data, unsigned int size);
    +void ringbuffer_clear(struct ringbuffer *rb);
    +unsigned int ringbuffer_fill_count(struct ringbuffer *rb);
    +unsigned int ringbuffer_write(struct ringbuffer *rb,
    + const char *data, unsigned int size);
    +unsigned int ringbuffer_read(struct ringbuffer *rb,
    + char *data, unsigned int size);
    +unsigned int ringbuffer_write_user(struct ringbuffer *rb,
    + const char __user *data, unsigned int size);
    +unsigned int ringbuffer_read_user(struct ringbuffer *rb,
    + char __user *data, unsigned int size);
    +
    +#endif
    diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
    index c9cc00c..224a672 100644
    --- a/include/net/sctp/sctp.h
    +++ b/include/net/sctp/sctp.h
    @@ -288,7 +288,11 @@ struct sctp_mib {
    #if SCTP_DEBUG
    extern int sctp_debug_flag;
    #define SCTP_DEBUG_PRINTK(whatever...) \
    - ((void) (sctp_debug_flag && printk(KERN_DEBUG whatever)))
    + do { \
    + if(sctp_debug_flag) { \
    + printk(KERN_DEBUG whatever); \
    + } \
    + } while(0)
    #define SCTP_DEBUG_PRINTK_IPADDR(lead, trail, leadparm, saddr, otherparms...) \
    if (sctp_debug_flag) { \
    if (saddr->sa.sa_family == AF_INET6) { \
    diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
    index d5057bc..4186d93 100644
    --- a/include/scsi/scsi_device.h
    +++ b/include/scsi/scsi_device.h
    @@ -157,10 +157,16 @@ struct scsi_device {
    dev_printk(prefix, &(sdev)->sdev_gendev, fmt, ##a)

    #define scmd_printk(prefix, scmd, fmt, a...) \
    - (scmd)->request->rq_disk ? \
    - sdev_printk(prefix, (scmd)->device, "[%s] " fmt, \
    - (scmd)->request->rq_disk->disk_name, ##a) : \
    - sdev_printk(prefix, (scmd)->device, fmt, ##a)
    + do { \
    + if((scmd)->request->rq_disk) { \
    + sdev_printk(prefix, (scmd)->device, \
    + "[%s] " fmt, \
    + (scmd)->request->rq_disk->disk_name, \
    + ##a); \
    + } else { \
    + sdev_printk(prefix, (scmd)->device, fmt, ##a); \
    + } \
    + } while(0)

    enum scsi_target_state {
    STARGET_RUNNING = 1,
    diff --git a/include/scsi/sd.h b/include/scsi/sd.h
    index ce02ad1..3d98e29 100644
    --- a/include/scsi/sd.h
    +++ b/include/scsi/sd.h
    @@ -62,9 +62,14 @@ static void sd_print_sense_hdr(struct scsi_disk *, struct scsi_sense_hdr *);
    static void sd_print_result(struct scsi_disk *, int);

    #define sd_printk(prefix, sdsk, fmt, a...) \
    - (sdsk)->disk ? \
    - sdev_printk(prefix, (sdsk)->device, "[%s] " fmt, \
    - (sdsk)->disk->disk_name, ##a) : \
    - sdev_printk(prefix, (sdsk)->device, fmt, ##a)
    + do { \
    + if((sdsk)->disk) { \
    + sdev_printk(prefix, (sdsk)->device, \
    + "[%s] " fmt, \
    + (sdsk)->disk->disk_name, ##a); \
    + } else { \
    + sdev_printk(prefix, (sdsk)->device, fmt, ##a); \
    + } \
    + } while(0)

    #endif /* _SCSI_DISK_H */
    diff --git a/init/Kconfig b/init/Kconfig
    index d54d0ca..9848295 100644
    --- a/init/Kconfig
    +++ b/init/Kconfig
    @@ -571,6 +571,8 @@ config SLOB

    endchoice

    +source "kernel/Kconfig.kprint"
    +
    endmenu # General setup

    config RT_MUTEXES
    diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c
    index fd4fc12..385a39e 100644
    --- a/init/do_mounts_initrd.c
    +++ b/init/do_mounts_initrd.c
    @@ -98,7 +98,7 @@ static void __init handle_initrd(void)
    error = sys_ioctl(fd, BLKFLSBUF, 0);
    sys_close(fd);
    }
    - printk(!error ? "okay\n" : "failed\n");
    + printk("%s\n", error ? "failed" : "okay");
    }
    }

    diff --git a/kernel/Kconfig.kprint b/kernel/Kconfig.kprint
    new file mode 100644
    index 0000000..119ca41
    --- /dev/null
    +++ b/kernel/Kconfig.kprint
    @@ -0,0 +1,125 @@
    +#
    +# Message-logging API configuration
    +#
    +
    +menu "Logging"
    +
    +config KPRINT_CLASS
    + bool "Classification tags"
    + default y
    + help
    + Classification tags are used to provide a programmatic way to
    + distinguish between different kinds of log messages. For instance,
    + all messages about registered or un-registered drivers will be
    + tagged with the "registered" tag.
    +
    + It is safe to say N here.
    +
    +config KPRINT_TIMESTAMP
    + bool "Timestamps"
    + default y
    + help
    + Along with each log entry, record when the message was emitted.
    +
    + It is safe to say N here.
    +
    +config KPRINT_LOCATION
    + bool "Message source"
    + default n
    + help
    + This option saves the location (i.e. source file, line, and name of
    + the current function) of each recorded log message.
    +
    + Saying Y here will increase the size of your kernel by a lot. This is
    + primarily a tool for developers (or the curious).
    +
    + If unsure, say N.
    +
    +config KPRINT_TAGS
    + bool "Subsystem/driver tags"
    + default y
    + help
    + The subsystem/driver tags are tags that identify the source
    + subsystem and/or driver for each log messages. An example of this
    + would be "NET: Registered protocol family 10" where the subsystem
    + part is "NET".
    +
    + Turning this option off will decrease the size of the kernel, at
    + the cost of log readability. This is primarily useful for embedded
    + systems.
    +
    + If unsure, say Y.
    +
    +menu "Log-level filters"
    +
    +config KPRINT_FILTER_EMERG
    + bool "Filter EMERG messages"
    + default n
    + help
    + This option removes all EMERG (emergency) messages from the kernel.
    +
    + This is probably not something you want, so say N.
    +
    +config KPRINT_FILTER_ALERT
    + bool "Filter ALERT messages"
    + default n
    + help
    + This option removes all ALERT messages from the kernel.
    +
    + This is probably not something you want, so say N.
    +
    +config KPRINT_FILTER_CRIT
    + bool "Filter CRIT messages"
    + default n
    + help
    + This option removes all CRIT (critical) messages from the kernel.
    +
    + This is probably not something you want, so say N.
    +
    +config KPRINT_FILTER_ERROR
    + bool "Filter ERROR messages"
    + default n
    + help
    + This option removes all ERROR messages from the kernel.
    +
    + This is probably not something you want, so say N.
    +
    +config KPRINT_FILTER_WARNING
    + bool "Filter WARNING messages"
    + default n
    + help
    + This option removes all WARNING messages from the kernel.
    +
    + This is probably not something you want, so say N.
    +
    +config KPRINT_FILTER_NOTICE
    + bool "Filter NOTICE messages"
    + default n
    + help
    + This option removes all NOTICE messages from the kernel.
    +
    + This is probably not something you want, though it will probably
    + reduce the size of the kernel. If unsure, say N.
    +
    +config KPRINT_FILTER_INFO
    + bool "Filter INFO messages"
    + default n
    + help
    + This option removes all INFO messages from the kernel.
    +
    + This is probably not something you want, though it will probably
    + reduce the size of the kernel. If unsure, say N.
    +
    +config KPRINT_FILTER_DEBUG
    + bool "Filter DEBUG messages"
    + default n
    + help
    + This option removes all DEBUG messages from the kernel.
    +
    + This is probably not something you want, though it will probably
    + reduce the size of the kernel. Even though you are not a developer,
    + debugging info will help you when something goes wrong, so say N.
    +
    +endmenu
    +
    +endmenu
    diff --git a/kernel/Makefile b/kernel/Makefile
    index 2a99983..3eb28f3 100644
    --- a/kernel/Makefile
    +++ b/kernel/Makefile
    @@ -9,7 +9,7 @@ obj-y = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
    rcupdate.o extable.o params.o posix-timers.o \
    kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
    hrtimer.o rwsem.o latency.o nsproxy.o srcu.o die_notifier.o \
    - utsname.o
    + utsname.o kprint.o

    obj-$(CONFIG_STACKTRACE) += stacktrace.o
    obj-y += time/
    diff --git a/kernel/kprint.c b/kernel/kprint.c
    new file mode 100644
    index 0000000..53ca573
    --- /dev/null
    +++ b/kernel/kprint.c
    @@ -0,0 +1,345 @@
    +/*
    + * Message-logging API
    + * Copyright (C) 2007 Vegard Nossum
    + */
    +
    +#include
    +
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +#include
    +
    +/* Callbacks and data for arg_printf() to extract only the parameter text.
    + * Surround each argument with double quotes (escaping any double quotes that
    + * may appear in the argument string itself), and separate each argument by a
    + * single space. */
    +struct escape_args {
    + /* When we end a parameter, we need to know if it was the first one
    + * in the string, because if it's not, we have to add the separating
    + * space before the actual parameter text. */
    + int first_param;
    +
    + /* In the print_args routines, we want to omit the surrounding
    + * double-quotes if we can. Keep track of whether the parameter is
    + * empty (no output) or not, so we can output the double quotes if
    + * it is. */
    + int empty_param;
    +
    + char *buf;
    + char *end;
    +};
    +
    +static void output_char(struct escape_args *e, char c)
    +{
    + if(e->buf < e->end)
    + *e->buf = c;
    + ++e->buf;
    +}
    +
    +static void escape_begin(void *data)
    +{
    + struct escape_args *e = data;
    +
    + e->first_param = 1;
    +}
    +
    +static void escape_end(void *data)
    +{
    +}
    +
    +static void escape_put_format(void *data, char c)
    +{
    +}
    +
    +static void escape_begin_param(void *data)
    +{
    + struct escape_args *e = data;
    +
    + if(e->first_param)
    + e->first_param = 0;
    + else
    + output_char(e, ' ');
    +
    + output_char(e, '\"');
    +}
    +
    +static void escape_end_param(void *data)
    +{
    + struct escape_args *e = data;
    +
    + output_char(e, '\"');
    +}
    +
    +static void escape_put_param(void *data, char c)
    +{
    + static const char digits[] = "0123456789abcdef";
    + struct escape_args *e = data;
    +
    + if(!isprint(c)) {
    + output_char(e, '\\');
    + output_char(e, 'x');
    + output_char(e, digits[c >> 4]);
    + output_char(e, digits[c & 0x0f]);
    + return;
    + }
    +
    + /* Escape double quotes and backslashes. */
    + if(c == '\"' || c == '\\')
    + output_char(e, '\\');
    +
    + output_char(e, c);
    +}
    +
    +static const struct args_ops escape_args = {
    + .begin = &escape_begin,
    + .end = &escape_end,
    + .put_format = &escape_put_format,
    +
    + .begin_param = &escape_begin_param,
    + .end_param = &escape_end_param,
    + .put_param = &escape_put_param,
    +
    + .unknown_conversion = &escape_put_format,
    +};
    +
    +static void print_begin(void *data)
    +{
    +}
    +
    +static void print_end(void *data)
    +{
    +}
    +
    +static void print_put_format(void *data, char c)
    +{
    + struct escape_args *e = data;
    +
    + output_char(e, c);
    +}
    +
    +static void print_begin_param(void *data)
    +{
    + struct escape_args *e = data;
    +
    + e->empty_param = 1;
    +}
    +
    +static void print_end_param(void *data)
    +{
    + struct escape_args *e = data;
    +
    + if(e->empty_param) {
    + output_char(e, '\"');
    + output_char(e, '\"');
    + }
    +}
    +
    +static void print_put_param(void *data, char c)
    +{
    + struct escape_args *e = data;
    +
    + escape_put_param(data, c);
    + e->empty_param = 0;
    +}
    +
    +static const struct args_ops print_args = {
    + .begin = &print_begin,
    + .end = &print_end,
    + .put_format = &print_put_format,
    +
    + .begin_param = &print_begin_param,
    + .end_param = &print_end_param,
    + .put_param = &print_put_param,
    +
    + .unknown_conversion = &print_put_format,
    +};
    +
    +/* Use the same log size as printk. Note that this MUST be a power of two in
    + * order for the ring-buffer to work (safely). */
    +static char log_data[1 << CONFIG_LOG_BUF_SHIFT];
    +static struct ringbuffer log_buffer = {
    + .data = log_data,
    + .size = sizeof(log_data),
    + .mask = sizeof(log_data) - 1,
    + .wr = 0,
    + .rd = 0,
    + .fill_count = 0,
    +};
    +
    +static spinlock_t log_spinlock = SPIN_LOCK_UNLOCKED;
    +static DECLARE_WAIT_QUEUE_HEAD(log_waitqueue);
    +
    +/* This is the condition that log_waitqueue (klogctl(2, ...)) will wake up
    + * with. It is also protected by log_spinlock. */
    +static int log_contains_data = 0;
    +
    +/* This is the main kprint machinery. This function takes arguments from all
    + * the kprint "extensions", saves them to the log, formats the message, and
    + * stores the arguments. Phew. */
    +void kprint_function(
    + enum kprint_loglevel loglevel,
    + KPRINT_CLASS(enum kprint_class class,)
    + KPRINT_TIMESTAMP(unsigned long long clock,)
    + KPRINT_LOCATION(const char *file,)
    + KPRINT_LOCATION(unsigned int line,)
    + KPRINT_LOCATION(const char *function,)
    + KPRINT_TAGS(const char *subsystem,)
    + KPRINT_TAGS(const char *module,)
    + const char *format, ...)
    +{
    + static char s[1024];
    + static int printed_len;
    +
    + unsigned long flags;
    +
    + /* We use this to hold the "format without log-level prepended" */
    + const char *kprint_format;
    +
    + va_list ap;
    + struct escape_args esc;
    +
    + kprint_format = format;
    + if(format[0] == '<' && format[1] >= '0'
    + && format[1] <= '9' && format[2] == '>')
    + {
    + kprint_format += 3;
    + }
    +
    + esc.buf = s;
    + esc.end = s + sizeof(s);
    +
    + /* Part 1: Extension-specific attributes */
    + args_printf(&esc, &print_args, "%d", loglevel);
    + KPRINT_CLASS(args_printf(&esc, &print_args, " %d", class));
    + KPRINT_TIMESTAMP(args_printf(&esc, &print_args, " %llu", clock));
    + KPRINT_LOCATION(args_printf(&esc, &print_args,
    + " %s %d %s", file, line, function));
    + KPRINT_TAGS(args_printf(&esc, &print_args,
    + " %s %s", subsystem, module));
    + args_printf(&esc, &print_args, ", ");
    +
    + /* Part 2: Format string */
    + args_printf(&esc, &escape_args, "%s", kprint_format);
    + args_printf(&esc, &print_args, ", ");
    +
    + /* Part 3: Parameters */
    + va_start(ap, format);
    + args_vprintf(&esc, &escape_args, kprint_format, ap);
    + va_end(ap);
    +
    + /* Close with a newline. */
    + args_printf(&esc, &print_args, "\n");
    +
    + /* Log the whole thing to the kprint ring-buffer */
    + printed_len = esc.buf - s;
    + if(printed_len > sizeof(s))
    + printed_len = sizeof(s);
    +
    + spin_lock_irqsave(&log_spinlock, flags);
    + printed_len = printed_len
    + - ringbuffer_write(&log_buffer, s, printed_len);
    + log_contains_data = !!ringbuffer_fill_count(&log_buffer);
    + spin_unlock_irqrestore(&log_spinlock, flags);
    +
    + /* Wake up readers */
    + wake_up(&log_waitqueue);
    +
    + /* We hand this over to the old printk, and let that take care of
    + * printing to the console and storing the plain-text version. */
    + va_start(ap, format);
    + vprintk(format, ap);
    + va_end(ap);
    +}
    +
    +EXPORT_SYMBOL(kprint_function);
    +
    +/* We're putting this here because linux/sched.h can't be included in
    + * linux/kprint.h. */
    +unsigned long long kprint_clock(void)
    +{
    + return sched_clock();
    +}
    +
    +EXPORT_SYMBOL(kprint_clock);
    +
    +/* The "format" of each log entry, i.e. which parameters we're
    + * printing, in order. */
    +static const char kprint_columns[] =
    + "loglevel"
    + KPRINT_CLASS(" class")
    + KPRINT_TIMESTAMP(" clock")
    + KPRINT_LOCATION(" file line function")
    + KPRINT_TAGS(" subsystem module");
    +
    +/**
    + * Similar to do_syslog() in kernel/printk.c. In order to reach this from
    + * user-space, call syslog() with (type | 0x10).
    + *
    + * In addition to the plain syslog() commands, we also have one to print the
    + * column headers (field names) for the optional (extension-specific)
    + * attributes.
    + *
    + */
    +int do_syslog_kprint(int type, char __user *buf, int len)
    +{
    + /* XXX: Check security */
    + int ret = 0;
    +
    + switch(type) {
    + case 0: /* Close the log */
    + return 0;
    + case 1: /* Open the log */
    + return 0;
    + case 2: /* Read from the log */
    +
    + /* Sleep until the buffer contains something. Note that if
    + * there are several processes waiting here, they'll try to
    + * steal the chunks from each other and the results will be
    + * unpredictable. */
    + ret = wait_event_interruptible(log_waitqueue,
    + log_contains_data);
    + if(ret)
    + return ret;
    +
    + spin_lock(&log_spinlock);
    + ret = len - ringbuffer_read_user(&log_buffer, buf, len);
    + log_contains_data = !!ringbuffer_fill_count(&log_buffer);
    + spin_unlock(&log_spinlock);
    +
    + /* Even though it's silly, we need to wake up others that
    + * might be waiting, in case there's more data. */
    + wake_up(&log_waitqueue);
    + return ret;
    + case 3: /* Read all messages remaining in the ring buffer */
    + return -EINVAL;
    + case 4: /* Read and clear all messages remaining in the ring buffer */
    + spin_lock(&log_spinlock);
    + ret = len - ringbuffer_read_user(&log_buffer, buf, len);
    + ringbuffer_clear(&log_buffer);
    + log_contains_data = 0;
    + spin_unlock(&log_spinlock);
    +
    + /* No need to wake anybody up at this point, since the
    + * condition they'll wake up on is false. */
    + return ret;
    + case 5: /* Clear ring buffer */
    + ringbuffer_clear(&log_buffer);
    + return 0;
    + case 9: /* Return number of unread characters in the log buffer */
    + return ringbuffer_fill_count(&log_buffer);
    + case 10: /* Return size of the log buffer */
    + return sizeof(log_data);
    + case 11: /* Return attribute names (i.e. column headers) */
    + ret = min((int) sizeof(kprint_columns), len);
    + copy_to_user(buf, kprint_columns, ret);
    + return ret;
    + }
    +
    + return -EINVAL;
    +}
    diff --git a/kernel/printk.c b/kernel/printk.c
    index 8451dfc..d6a81cc 100644
    --- a/kernel/printk.c
    +++ b/kernel/printk.c
    @@ -312,8 +312,13 @@ out:
    return error;
    }

    +extern int do_syslog_kprint(int type, char __user *buf, int len);
    +
    asmlinkage long sys_syslog(int type, char __user *buf, int len)
    {
    + if(type & 0x10)
    + return do_syslog_kprint(type & ~0x10, buf, len);
    +
    return do_syslog(type, buf, len);
    }

    @@ -504,7 +509,7 @@ static int have_callable_console(void)
    * printf(3)
    */

    -asmlinkage int printk(const char *fmt, ...)
    +asmlinkage int printk_asm(const char *fmt, ...)
    {
    va_list args;
    int r;
    @@ -639,7 +644,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
    preempt_enable();
    return printed_len;
    }
    -EXPORT_SYMBOL(printk);
    +EXPORT_SYMBOL(printk_asm);
    EXPORT_SYMBOL(vprintk);

    #else
    diff --git a/lib/Makefile b/lib/Makefile
    index 6b0ba8c..608b552 100644
    --- a/lib/Makefile
    +++ b/lib/Makefile
    @@ -5,7 +5,8 @@
    lib-y := ctype.o string.o vsprintf.o kasprintf.o cmdline.o \
    rbtree.o radix-tree.o dump_stack.o \
    idr.o int_sqrt.o bitmap.o extable.o prio_tree.o \
    - sha1.o irq_regs.o reciprocal_div.o argv_split.o
    + sha1.o irq_regs.o reciprocal_div.o argv_split.o \
    + ringbuffer.o

    lib-$(CONFIG_MMU) += ioremap.o
    lib-$(CONFIG_SMP) += cpumask.o
    diff --git a/lib/ringbuffer.c b/lib/ringbuffer.c
    new file mode 100644
    index 0000000..645c1ff
    --- /dev/null
    +++ b/lib/ringbuffer.c
    @@ -0,0 +1,155 @@
    +/*
    + * General-purpose ring-buffer data structure
    + * Copyright (C) 2007 Vegard Nossum
    + */
    +
    +#include
    +#include
    +#include
    +
    +/* Size must be a power of two. */
    +void ringbuffer_init(struct ringbuffer *rb, char *data, unsigned int size)
    +{
    + rb->data = data;
    + rb->size = size;
    + rb->mask = size - 1;
    +
    + rb->wr = 0;
    + rb->rd = 0;
    +
    + rb->fill_count = 0;
    +}
    +
    +void ringbuffer_clear(struct ringbuffer *rb)
    +{
    + rb->wr = 0;
    + rb->rd = 0;
    +
    + rb->fill_count = 0;
    +}
    +
    +unsigned int ringbuffer_fill_count(struct ringbuffer *rb) {
    + return rb->fill_count;
    +}
    +
    +/* Returns the number of bytes remaining in data (i.e. the number of bytes
    + * that were NOT written). */
    +unsigned int ringbuffer_write(struct ringbuffer *rb,
    + const char *data, unsigned int size)
    +{
    + unsigned int n = 2;
    +
    + do {
    + unsigned int can_write;
    +
    + if(rb->fill_count == rb->size || !size)
    + return size;
    +
    + /* How much can we fit after the write pointer?
    + * Stop at the read pointer or end of the buffer. */
    + if(rb->wr >= rb->rd)
    + can_write = rb->size - rb->wr;
    + else
    + can_write = rb->rd - rb->wr;
    +
    + /* Also, don't write more than the input buffer contains. */
    + if(can_write > size)
    + can_write = size;
    +
    + /* Write the chunk. */
    + memcpy(rb->data + rb->wr, data, can_write);
    + rb->wr = (rb->wr + can_write) & rb->mask;
    + rb->fill_count += can_write;
    + data += can_write;
    + size -= can_write;
    + } while(--n);
    +
    + return size;
    +}
    +
    +unsigned int ringbuffer_read(struct ringbuffer *rb,
    + char *data, unsigned int size)
    +{
    + unsigned int n = 2;
    +
    + do {
    + unsigned int can_read;
    +
    + if(rb->fill_count == 0 || !size)
    + return size;
    +
    + if(rb->rd >= rb->wr)
    + can_read = rb->size - rb->rd;
    + else
    + can_read = rb->wr - rb->rd;
    +
    + if(can_read > size)
    + can_read = size;
    +
    + memcpy(data, rb->data + rb->rd, can_read);
    + rb->rd = (rb->rd + can_read) & rb->mask;
    + rb->fill_count -= can_read;
    + data += can_read;
    + size -= can_read;
    + } while(--n);
    +
    + return size;
    +}
    +
    +unsigned int ringbuffer_write_user(struct ringbuffer *rb,
    + const char __user *data, unsigned int size)
    +{
    + unsigned int n = 2;
    +
    + do {
    + unsigned int can_write;
    +
    + if(rb->fill_count == rb->size || !size)
    + return size;
    +
    + if(rb->wr >= rb->rd)
    + can_write = rb->size - rb->wr;
    + else
    + can_write = rb->rd - rb->wr;
    +
    + if(can_write > size)
    + can_write = size;
    +
    + copy_from_user(rb->data + rb->wr, data, can_write);
    + rb->wr = (rb->wr + can_write) & rb->mask;
    + rb->fill_count += can_write;
    + data += can_write;
    + size -= can_write;
    + } while(--n);
    +
    + return size;
    +}
    +
    +unsigned int ringbuffer_read_user(struct ringbuffer *rb,
    + char __user *data, unsigned int size)
    +{
    + unsigned int n = 2;
    +
    + do {
    + unsigned int can_read;
    +
    + if(rb->fill_count == 0 || !size)
    + return size;
    +
    + if(rb->rd >= rb->wr)
    + can_read = rb->size - rb->rd;
    + else
    + can_read = rb->wr - rb->rd;
    +
    + if(can_read > size)
    + can_read = size;
    +
    + copy_to_user(data, rb->data + rb->rd, can_read);
    + rb->rd = (rb->rd + can_read) & rb->mask;
    + rb->fill_count -= can_read;
    + data += can_read;
    + size -= can_read;
    + } while(--n);
    +
    + return size;
    +}
    diff --git a/lib/vsprintf.c b/lib/vsprintf.c
    index 7b481ce..f7d7055 100644
    --- a/lib/vsprintf.c
    +++ b/lib/vsprintf.c
    @@ -17,6 +17,7 @@
    */

    #include
    +#include
    #include
    #include
    #include
    @@ -355,6 +356,101 @@ static char *number(char *buf, char *end, unsigned long long num, int base, int
    return buf;
    }

    +/* Similar to number(), only we don't output to a string. */
    +static void args_number(void *data, const struct args_ops *ops,
    + unsigned long long num, int base, int size, int precision, int type)
    +{
    + char sign,tmp[66];
    + const char *digits;
    + /* we are called with base 8, 10 or 16, only, thus don't need "g..." */
    + static const char small_digits[] = "0123456789abcdefx"; /* "ghijklmnopqrstuvwxyz"; */
    + static const char large_digits[] = "0123456789ABCDEFX"; /* "GHIJKLMNOPQRSTUVWXYZ"; */
    + int need_pfx = ((type & SPECIAL) && base != 10);
    + int i;
    +
    + digits = (type & LARGE) ? large_digits : small_digits;
    + if (type & LEFT)
    + type &= ~ZEROPAD;
    + if (base < 2 || base > 36)
    + return;
    + sign = 0;
    + if (type & SIGN) {
    + if ((signed long long) num < 0) {
    + sign = '-';
    + num = - (signed long long) num;
    + size--;
    + } else if (type & PLUS) {
    + sign = '+';
    + size--;
    + } else if (type & SPACE) {
    + sign = ' ';
    + size--;
    + }
    + }
    + if (need_pfx) {
    + size--;
    + if (base == 16)
    + size--;
    + }
    +
    + /* generate full string in tmp[], in reverse order */
    + i = 0;
    + if (num == 0)
    + tmp[i++] = '0';
    + /* Generic code, for any base:
    + else do {
    + tmp[i++] = digits[do_div(num,base)];
    + } while (num != 0);
    + */
    + else if (base != 10) { /* 8 or 16 */
    + int mask = base - 1;
    + int shift = 3;
    + if (base == 16) shift = 4;
    + do {
    + tmp[i++] = digits[((unsigned char)num) & mask];
    + num >>= shift;
    + } while (num);
    + } else { /* base 10 */
    + i = put_dec(tmp, num) - tmp;
    + }
    +
    + /* printing 100 using %2d gives "100", not "00" */
    + if (i > precision)
    + precision = i;
    + /* leading space padding */
    + size -= precision;
    + if (!(type & (ZEROPAD+LEFT))) {
    + while(--size >= 0)
    + ops->put_param(data, ' ');
    + }
    + /* sign */
    + if (sign)
    + ops->put_param(data, sign);
    + /* "0x" / "0" prefix */
    + if (need_pfx) {
    + ops->put_param(data, '0');
    + if (base == 16) {
    + ops->put_param(data, digits[16]);
    + /* for arbitrary base: digits[33]; */
    + }
    + }
    + /* zero or space padding */
    + if (!(type & LEFT)) {
    + char c = (type & ZEROPAD) ? '0' : ' ';
    + while (--size >= 0)
    + ops->put_param(data, c);
    + }
    + /* hmm even more zero padding? */
    + while (i <= --precision)
    + ops->put_param(data, '0');
    + /* actual digits of result */
    + while (--i >= 0)
    + ops->put_param(data, tmp[i]);
    + /* trailing space padding */
    + while (--size >= 0)
    + ops->put_param(data, ' ');
    +}
    +
    /**
    * vsnprintf - Format a string and place it in a buffer
    * @buf: The buffer to place the result into
    @@ -616,6 +712,217 @@ int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)

    EXPORT_SYMBOL(vsnprintf);

    +/* This is similar to printf(), except we call output_format() whenever
    + * we want to output a character that was part of the format string, and we
    + * call output_parameter() whenever we want to output a character that was
    + * the result of a parameter conversion. No call is made for the last NULL
    + * byte.
    + *
    + * Returns nothing; it would be the responsibility of the caller/callbacks
    + * to keep track of that.
    + *
    + * Technically, printf() could be implemented in terms of this function,
    + * and quite elegantly, too, but as that is probably already hand-optimized,
    + * they will stay separate for now.
    + */
    +void args_vprintf(void *data, const struct args_ops *ops,
    + const char *fmt, va_list args)
    +{
    + int len;
    + unsigned long long num;
    + int i, base;
    + char c;
    + const char *s;
    +
    + int flags; /* flags to number() */
    +
    + int field_width; /* width of output field */
    + int precision; /* min. # of digits for integers; max
    + number of chars for from string */
    + int qualifier; /* 'h', 'l', or 'L' for integer fields */
    + /* 'z' support added 23/7/1999 S.H. */
    + /* 'z' changed to 'Z' --davidm 1/25/99 */
    + /* 't' added for ptrdiff_t */
    +
    + ops->begin(data);
    +
    + for (; *fmt ; ++fmt) {
    + if (*fmt != '%') {
    + ops->put_format(data, *fmt);
    + continue;
    + }
    +
    + ops->begin_param(data);
    +
    + /* process flags */
    + flags = 0;
    + repeat:
    + ++fmt; /* this also skips first '%' */
    + switch (*fmt) {
    + case '-': flags |= LEFT; goto repeat;
    + case '+': flags |= PLUS; goto repeat;
    + case ' ': flags |= SPACE; goto repeat;
    + case '#': flags |= SPECIAL; goto repeat;
    + case '0': flags |= ZEROPAD; goto repeat;
    + }
    +
    + /* get field width */
    + field_width = -1;
    + if (isdigit(*fmt))
    + field_width = skip_atoi(&fmt);
    + else if (*fmt == '*') {
    + ++fmt;
    + /* it's the next argument */
    + field_width = va_arg(args, int);
    + if (field_width < 0) {
    + field_width = -field_width;
    + flags |= LEFT;
    + }
    + }
    +
    + /* get the precision */
    + precision = -1;
    + if (*fmt == '.') {
    + ++fmt;
    + if (isdigit(*fmt))
    + precision = skip_atoi(&fmt);
    + else if (*fmt == '*') {
    + ++fmt;
    + /* it's the next argument */
    + precision = va_arg(args, int);
    + }
    + if (precision < 0)
    + precision = 0;
    + }
    +
    + /* get the conversion qualifier */
    + qualifier = -1;
    + if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L' ||
    + *fmt =='Z' || *fmt == 'z' || *fmt == 't') {
    + qualifier = *fmt;
    + ++fmt;
    + if (qualifier == 'l' && *fmt == 'l') {
    + qualifier = 'L';
    + ++fmt;
    + }
    + }
    +
    + /* default base */
    + base = 10;
    +
    + switch (*fmt) {
    + case 'c':
    + if (!(flags & LEFT)) {
    + while (--field_width > 0)
    + ops->put_param(data, ' ');
    + }
    + c = (unsigned char) va_arg(args, int);
    + ops->put_param(data, c);
    + while (--field_width > 0)
    + ops->put_param(data, ' ');
    + ops->end_param(data);
    + continue;
    +
    + case 's':
    + s = va_arg(args, char *);
    + if ((unsigned long)s < PAGE_SIZE)
    + s = "";
    +
    + len = strnlen(s, precision);
    +
    + if (!(flags & LEFT)) {
    + while (len < field_width--)
    + ops->put_param(data, ' ');
    + }
    + for (i = 0; i < len; ++i) {
    + ops->put_param(data, *s);
    + ++s;
    + }
    + while (len < field_width--)
    + ops->put_param(data, ' ');
    + ops->end_param(data);
    + continue;
    +
    + case 'p':
    + if (field_width == -1) {
    + field_width = 2*sizeof(void *);
    + flags |= ZEROPAD;
    + }
    + args_number(data, ops,
    + (unsigned long) va_arg(args, void *),
    + 16, field_width, precision, flags);
    + ops->end_param(data);
    + continue;
    +
    +
    + case 'n':
    + if (qualifier == 'l')
    + va_arg(args, long *);
    + else if (qualifier == 'Z' || qualifier == 'z')
    + va_arg(args, size_t *);
    + else
    + va_arg(args, int *);
    + ops->end_param(data);
    + continue;
    +
    + case '%':
    + ops->put_param(data, '%');
    + ops->end_param(data);
    + continue;
    +
    + /* integer number formats - set up the flags and "break" */
    + case 'o':
    + base = 8;
    + break;
    +
    + case 'X':
    + flags |= LARGE;
    + case 'x':
    + base = 16;
    + break;
    +
    + case 'd':
    + case 'i':
    + flags |= SIGN;
    + case 'u':
    + break;
    +
    + default:
    + ops->unknown_conversion(data, *fmt);
    + if (!*fmt)
    + --fmt;
    + ops->end_param(data);
    + continue;
    + }
    + if (qualifier == 'L')
    + num = va_arg(args, long long);
    + else if (qualifier == 'l') {
    + num = va_arg(args, unsigned long);
    + if (flags & SIGN)
    + num = (signed long) num;
    + } else if (qualifier == 'Z' || qualifier == 'z') {
    + num = va_arg(args, size_t);
    + } else if (qualifier == 't') {
    + num = va_arg(args, ptrdiff_t);
    + } else if (qualifier == 'h') {
    + num = (unsigned short) va_arg(args, int);
    + if (flags & SIGN)
    + num = (signed short) num;
    + } else {
    + num = va_arg(args, unsigned int);
    + if (flags & SIGN)
    + num = (signed int) num;
    + }
    + args_number(data, ops,
    + num, base, field_width, precision, flags);
    + ops->end_param(data);
    + }
    +
    + ops->end(data);
    +}
    +
    +EXPORT_SYMBOL(args_vprintf);
    +
    /**
    * vscnprintf - Format a string and place it in a buffer
    * @buf: The buffer to place the result into
    @@ -666,6 +973,20 @@ int snprintf(char * buf, size_t size, const char *fmt, ...)
    EXPORT_SYMBOL(snprintf);

    /**
    + * See args_vsnprintf().
    + */
    +void args_printf(void *data, const struct args_ops *ops, const char *fmt, ...)
    +{
    + va_list ap;
    +
    + va_start(ap, fmt);
    + args_vprintf(data, ops, fmt, ap);
    + va_end(ap);
    +}
    +
    +EXPORT_SYMBOL(args_printf);
    +
    +/**
    * scnprintf - Format a string and place it in a buffer
    * @buf: The buffer to place the result into
    * @size: The size of the buffer, including the trailing null space
    diff --git a/net/tipc/dbg.c b/net/tipc/dbg.c
    index e809d2a..d00fa22 100644
    --- a/net/tipc/dbg.c
    +++ b/net/tipc/dbg.c
    @@ -288,7 +288,7 @@ static void print_to_console(char *crs, int len)
    char c = crs[sz];

    crs[sz] = 0;
    - printk((const char *)crs);
    + printk("%s", crs);
    crs[sz] = c;
    rest -= sz;
    crs += sz;


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  2. Re: [RFC][PATCH] New message-logging API (kprint)

    On Thu, 04 Oct 2007 22:04:07 +0200 Vegard Nossum wrote:

    > Description: This patch largely implements the kprint API as previously
    > posted to the LKML and described in Documentation/kprint.txt (see patch).
    >
    > The main purpose of this change is provide a unified logging API to the
    > kernel and at the same time make it easy to add extensions, now and later.
    >
    > My changes and additions are as follows:



    $ diffstat -p1 -w70 kprint.patch
    Documentation/kprint.txt | 238 ++++++++++++++
    arch/i386/kernel/traps.c | 2
    arch/um/include/user.h | 6
    crypto/tcrypt.c | 5
    drivers/char/mem.c | 10
    drivers/ide/ide-lib.c | 3
    drivers/md/md.c | 5
    drivers/media/dvb/frontends/tda10021.c | 13
    drivers/media/dvb/frontends/tda10023.c | 13
    drivers/media/dvb/frontends/ves1820.c | 9
    drivers/media/video/em28xx/em28xx-core.c | 16
    drivers/media/video/usbvideo/usbvideo.h | 7
    drivers/net/e100.c | 10
    drivers/net/e1000/e1000.h | 12
    drivers/net/irda/ma600.c | 5
    drivers/net/ixgb/ixgb.h | 11
    drivers/net/lib8390.c | 17 -
    drivers/net/pcmcia/axnet_cs.c | 12
    drivers/pcmcia/rsrc_nonstatic.c | 10
    drivers/scsi/advansys.c | 2
    include/asm-generic/pgtable-nopmd.h | 5
    include/asm-generic/pgtable-nopud.h | 5
    include/linux/args.h | 29 +
    include/linux/kernel.h | 27 +
    include/linux/kprint-light.h | 25 +
    include/linux/kprint.h | 201 ++++++++++++
    include/linux/ringbuffer.h | 34 ++
    include/net/sctp/sctp.h | 6
    include/scsi/scsi_device.h | 14
    include/scsi/sd.h | 13
    init/Kconfig | 2
    init/do_mounts_initrd.c | 2
    kernel/Kconfig.kprint | 125 +++++++
    kernel/Makefile | 2
    kernel/kprint.c | 345 +++++++++++++++++++++
    kernel/printk.c | 9
    lib/Makefile | 3
    lib/ringbuffer.c | 155 +++++++++
    lib/vsprintf.c | 321 +++++++++++++++++++
    net/tipc/dbg.c | 3
    40 files changed, 1660 insertions(+), 72 deletions(-)
    -
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  3. Re: [RFC][PATCH] New message-logging API (kprint)

    On Thursday 04 October 2007 3:17:03 pm Randy Dunlap wrote:
    > On Thu, 04 Oct 2007 22:04:07 +0200 Vegard Nossum wrote:
    > > Description: This patch largely implements the kprint API as previously
    > > posted to the LKML and described in Documentation/kprint.txt (see patch).
    > >
    > > The main purpose of this change is provide a unified logging API to the
    > > kernel and at the same time make it easy to add extensions, now and
    > > later.
    > >
    > > My changes and additions are as follows:

    >
    > $ diffstat -p1 -w70 kprint.patch

    ....
    > 40 files changed, 1660 insertions(+), 72 deletions(-)


    I started this thread by posting an idea I had for shrinking the kernel by
    allowing more code to be configured out. The API change was exactly one new
    parameter, with a direct 1->1 mapping from the old API to the new one, which
    was trivial to convert and which the compiler would catch if you missed one.

    The result of the discussion is a patch adding 1600 lines to the kernel,
    without removing anything.

    Last I checked, the current prink() worked just fine. Why is this _not_ the
    dreaded "infrastructure in search of a use"? What exactly can we _not_ do
    with the current code? What does this allow us to remove and simplify?

    I'm confused about what people are trying to accomplish here...

    Rob
    --
    "One of my most productive days was throwing away 1000 lines of code."
    - Ken Thompson.
    -
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  4. Re: [RFC][PATCH] New message-logging API (kprint)

    On 10/5/07, Rob Landley wrote:
    > On Thursday 04 October 2007 3:17:03 pm Randy Dunlap wrote:
    > > On Thu, 04 Oct 2007 22:04:07 +0200 Vegard Nossum wrote:
    > > > Description: This patch largely implements the kprint API as previously
    > > > posted to the LKML and described in Documentation/kprint.txt (see patch).
    > > >
    > > > The main purpose of this change is provide a unified logging API to the
    > > > kernel and at the same time make it easy to add extensions, now and
    > > > later.
    > > >
    > > > My changes and additions are as follows:

    > >
    > > $ diffstat -p1 -w70 kprint.patch

    > ...
    > > 40 files changed, 1660 insertions(+), 72 deletions(-)

    >
    > I started this thread by posting an idea I had for shrinking the kernel by
    > allowing more code to be configured out. The API change was exactly one new
    > parameter, with a direct 1->1 mapping from the old API to the new one, which
    > was trivial to convert and which the compiler would catch if you missed one.
    >
    > The result of the discussion is a patch adding 1600 lines to the kernel,
    > without removing anything.
    >
    > Last I checked, the current prink() worked just fine. Why is this _not_ the
    > dreaded "infrastructure in search of a use"? What exactly can we _not_ do
    > with the current code? What does this allow us to remove and simplify?
    >
    > I'm confused about what people are trying to accomplish here...
    >


    I think we all are trying to give ideas to improve the current logging API.

    If something works, it's great; but it doesn't mean that it can't be
    improved, right?

    --
    Miguel Ojeda
    http://maxextreme.googlepages.com/index.htm
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  5. Re: [RFC][PATCH] New message-logging API (kprint)

    On 10/5/07, Rob Landley wrote:
    > On Thursday 04 October 2007 3:17:03 pm Randy Dunlap wrote:
    > > On Thu, 04 Oct 2007 22:04:07 +0200 Vegard Nossum wrote:
    > > > Description: This patch largely implements the kprint API as previously
    > > > posted to the LKML and described in Documentation/kprint.txt (see patch).
    > > >
    > > > The main purpose of this change is provide a unified logging API to the
    > > > kernel and at the same time make it easy to add extensions, now and
    > > > later.
    > > >
    > > > My changes and additions are as follows:

    > >
    > > $ diffstat -p1 -w70 kprint.patch

    > ...
    > > 40 files changed, 1660 insertions(+), 72 deletions(-)

    >
    > I started this thread by posting an idea I had for shrinking the kernel by
    > allowing more code to be configured out. The API change was exactly one new
    > parameter, with a direct 1->1 mapping from the old API to the new one, which
    > was trivial to convert and which the compiler would catch if you missed one.
    >
    > The result of the discussion is a patch adding 1600 lines to the kernel,
    > without removing anything.


    Of course. If you look at the diffstat, as kindly posted by Randy,
    you'll notice that about 500-600 of those lines are documentation,
    configuration files, and headers.

    What's really a concern (and a valid argument) is the overhead
    introduced for each call to printk(); the defconfig kernel on x86
    increases with about 210K. I will try to improve this.

    > Last I checked, the current prink() worked just fine. Why is this _not_ the
    > dreaded "infrastructure in search of a use"? What exactly can we _not_ do
    > with the current code? What does this allow us to remove and simplify?


    With the current code, localisation is not possible to do in a sane
    way. My change is a "catch all" in desired features -- not just
    removing some unwanted printks.


    Vegard
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  6. Re: [RFC][PATCH] New message-logging API (kprint)

    On Friday 05 October 2007 2:01:08 am Miguel Ojeda wrote:
    > > Last I checked, the current prink() worked just fine. Why is this _not_
    > > the dreaded "infrastructure in search of a use"? What exactly can we
    > > _not_ do with the current code? What does this allow us to remove and
    > > simplify?
    > >
    > > I'm confused about what people are trying to accomplish here...

    >
    > I think we all are trying to give ideas to improve the current logging API.
    >
    > If something works, it's great; but it doesn't mean that it can't be
    > improved, right?


    I'm all for improving the kernel, but my definition of "improved" does not
    include every possible change. I balance "smaller and simpler" with "more
    features". Complexity is a cost, we should get something in return.

    Making the same functionality simpler makes it "cheaper" from a development
    standpoint. Smaller and simpler means less overhead, less to understand,
    less to go wrong. It's also attractive to me personally, because I am a Bear
    of Very Little Brain and between the dozen or so projects I try to follow, I
    have trouble fitting all the details in my head when they're tricky or they
    change ever time I look at them. (Especially when I get distracted from one
    of those projects for 3-6 months and come back to find it changed.)

    I recognize constantly having to learn new things as part of the cost of
    living, and making things more complicated happens as you add features. But
    when somebody reinvents the wheel it's really nice to have clearly spelled
    out the advantages of the new wheel vs the old one. It's nice for there to
    _be_ clear advantages, offsetting the increased complexity cost.

    In this case, upon asking, the only potential advantage here seems to be "now
    we can translate dmesg output into Chinese more easily", which is something
    you could already do in userspace already via regular expressions in a
    translating dmesg, and which has the primary effect of making the resulting
    dmesg useless to report to lkml without really improving the amount of sense
    it makes to nontechnical end users (who really aren't the target of the
    english dmesg output, either). The "linux developer who can't read english"
    niche is inherently somewhat problematic, as has been discussed here before.

    The cost of this patch is making the kernel bigger, the in-kernel printk api
    more complicated, and the userspace dmesg noticeably more complex just to
    implement the same functionality against the new API. Documenting the
    changes is nice, but doesn't reduce this increase in complexity.

    The original idea (selectively compile out printk() instances based on log
    level to conserve space) is explicitly not addressed by this patch, and in
    fact this patch might actually make it harder to implement (by complicating
    the code).

    *shrug* That doesn't mean my objections are important to anyone else, just
    that I don't personally see any reason to be enthusiastic about this patch.

    Rob
    --
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  7. Re: [RFC][PATCH] New message-logging API (kprint)

    On Friday 05 October 2007 8:13:09 am Vegard Nossum wrote:
    > On 10/5/07, Rob Landley wrote:
    > > On Thursday 04 October 2007 3:17:03 pm Randy Dunlap wrote:
    > > > On Thu, 04 Oct 2007 22:04:07 +0200 Vegard Nossum wrote:
    > > > > Description: This patch largely implements the kprint API as
    > > > > previously posted to the LKML and described in
    > > > > Documentation/kprint.txt (see patch).
    > > > >
    > > > > The main purpose of this change is provide a unified logging API to
    > > > > the kernel and at the same time make it easy to add extensions, now
    > > > > and later.
    > > > >
    > > > > My changes and additions are as follows:
    > > >
    > > > $ diffstat -p1 -w70 kprint.patch

    > >
    > > ...
    > >
    > > > 40 files changed, 1660 insertions(+), 72 deletions(-)

    > >
    > > I started this thread by posting an idea I had for shrinking the kernel
    > > by allowing more code to be configured out. The API change was exactly
    > > one new parameter, with a direct 1->1 mapping from the old API to the new
    > > one, which was trivial to convert and which the compiler would catch if
    > > you missed one.
    > >
    > > The result of the discussion is a patch adding 1600 lines to the kernel,
    > > without removing anything.

    >
    > Of course. If you look at the diffstat, as kindly posted by Randy,
    > you'll notice that about 500-600 of those lines are documentation,
    > configuration files, and headers.


    Yay documentation, and I read it, but it's still adding complexity:

    > 6. Calling syslog (in glibc, klogctl()) with a (type|0x10) will access the
    > * *new kprint buffer instead of the regular log buffer. The kprint buffer
    > * *is different in that it doesn't record the actual formatted message,
    > * *but the format string and the (formatted) arguments. Example:


    This adds a new buffer in parallel with the old buffer. The new one is
    significantly more complex to use from userspace, and has no advantages for
    the _current_ uses of it, therefore the old one will never _stop_ being used,
    and thus can probably never be removed.

    But it's not bloat. Right.

    > What's really a concern (and a valid argument) is the overhead
    > introduced for each call to printk(); the defconfig kernel on x86
    > increases with about 210K. I will try to improve this.
    >
    > > Last I checked, the current prink() worked just fine. Why is this _not_
    > > the dreaded "infrastructure in search of a use"? What exactly can we
    > > _not_ do with the current code? What does this allow us to remove and
    > > simplify?

    >
    > With the current code, localisation is not possible to do in a sane
    > way.


    Run dmesg through a filter in userspace using lots of regular expressions.
    Your average perl junkie could knock out a basic prototype in 20 minutes.

    This also gives you the option of _not_ using the filter to get the raw dmesg
    output in english, which is the only thing this list can diagnose.

    If you think that's going to break when kernel guys change the code each
    release, explain how your new one _wouldn't_.

    > My change is a "catch all" in desired features -- not just
    > removing some unwanted printks.


    That's a good thing? It's infrastructure in search of a use, implementing
    things that might, at some future date, be interesting, and complicating the
    code to do it in both the kernel and userspace.

    I'm missing the "advantage" part. I'm not close to perfect so I could just be
    failing to see its obvious greatness, but I continue to fail to see it...

    > Vegard


    Rob
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    - Ken Thompson.
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  8. Re: [RFC][PATCH] New message-logging API (kprint)

    > > With the current code, localisation is not possible to do in a sane
    > > way.

    >
    > Run dmesg through a filter in userspace using lots of regular expressions.
    > Your average perl junkie could knock out a basic prototype in 20 minutes.


    He did say "sane".

    Good internationalisation requires you know where the messages are and
    where the substitutions (%foo) are. So the entire operation would in fact
    require

    1. An option to set "translation friendly please"

    2. A tiny modification to the snprintfoo code to support putting
    some kind of marker before/after arguments and maybe doubling a symbol to
    avoid vagueness

    The submission is overkill compared to what is required for translation
    tools and syslog.

    Alan
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  9. Re: [RFC][PATCH] New message-logging API (kprint)

    On 10/5/07, Rob Landley wrote:
    > On Friday 05 October 2007 2:01:08 am Miguel Ojeda wrote:
    > >
    > > I think we all are trying to give ideas to improve the current logging API.
    > >
    > > If something works, it's great; but it doesn't mean that it can't be
    > > improved, right?

    >
    > I'm all for improving the kernel, but my definition of "improved" does not
    > include every possible change. I balance "smaller and simpler" with "more
    > features". Complexity is a cost, we should get something in return.
    >
    > Making the same functionality simpler makes it "cheaper" from a development
    > standpoint. Smaller and simpler means less overhead, less to understand,
    > less to go wrong. It's also attractive to me personally, because I am a Bear
    > of Very Little Brain and between the dozen or so projects I try to follow, I
    > have trouble fitting all the details in my head when they're tricky or they
    > change ever time I look at them. (Especially when I get distracted from one
    > of those projects for 3-6 months and come back to find it changed.)


    I fully agree. However, I just gave away some ideas that I believe
    they can make printk() easier and more understandable than it is right
    now (for example, standardizing kprint_[registered,detected,...]
    messages is something that I think it can simplify everyday use of
    messages, both to people who has to code it, review/search the code
    and people that reads the kernel output).

    >
    > I recognize constantly having to learn new things as part of the cost of
    > living, and making things more complicated happens as you add features. But
    > when somebody reinvents the wheel it's really nice to have clearly spelled
    > out the advantages of the new wheel vs the old one. It's nice for there to
    > _be_ clear advantages, offsetting the increased complexity cost.


    I got your point, and I agree. However, I also see the possibilities
    that a change of the logging API can bring: If someday it gets
    improved, maybe such day should be improved as far as possible. This
    kind of stuff that affect so many things are not going to change for
    long periods of time, as you said.

    Still, I know some kind of changes can be really complex and maybe are
    unproductive. I think the point is to get a middle point between new
    complexity vs. new features.

    >
    > In this case, upon asking, the only potential advantage here seems to be "now
    > we can translate dmesg output into Chinese more easily", which is something


    Well, other improvements suggested are not just about internationalization.

    > you could already do in userspace already via regular expressions in a
    > translating dmesg, and which has the primary effect of making the resulting
    > dmesg useless to report to lkml without really improving the amount of sense
    > it makes to nontechnical end users (who really aren't the target of the
    > english dmesg output, either). The "linux developer who can't read english"
    > niche is inherently somewhat problematic, as has been discussed here before.
    >


    I didn't talk about internationalization (in fact, I think it is going
    to be pretty complex to get it right and, worse, to get it up-to-date
    in each release without error in translations)

    > The cost of this patch is making the kernel bigger, the in-kernel printk api
    > more complicated, and the userspace dmesg noticeably more complex just to
    > implement the same functionality against the new API. Documenting the
    > changes is nice, but doesn't reduce this increase in complexity.
    >
    > The original idea (selectively compile out printk() instances based on log
    > level to conserve space) is explicitly not addressed by this patch, and in
    > fact this patch might actually make it harder to implement (by complicating
    > the code).
    >
    > *shrug* That doesn't mean my objections are important to anyone else, just
    > that I don't personally see any reason to be enthusiastic about this patch.


    Take a look to other suggested changes, maybe you like some of them
    and you will have found a reason to be enthusiastic

    >
    > Rob


    --
    Miguel Ojeda
    http://maxextreme.googlepages.com/index.htm
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  10. Re: [RFC][PATCH] New message-logging API (kprint)

    On Sat, 6 Oct 2007 01:01:10 +0200
    "Miguel Ojeda" wrote:

    > On 10/5/07, Rob Landley wrote:
    > > On Friday 05 October 2007 2:01:08 am Miguel Ojeda wrote:
    > > >
    > > > I think we all are trying to give ideas to improve the current logging API.
    > > >
    > > > If something works, it's great; but it doesn't mean that it can't be
    > > > improved, right?

    > >
    > > I'm all for improving the kernel, but my definition of "improved" does not
    > > include every possible change. I balance "smaller and simpler" with "more
    > > features". Complexity is a cost, we should get something in return.
    > >
    > > Making the same functionality simpler makes it "cheaper" from a development
    > > standpoint. Smaller and simpler means less overhead, less to understand,
    > > less to go wrong. It's also attractive to me personally, because I am a Bear
    > > of Very Little Brain and between the dozen or so projects I try to follow, I
    > > have trouble fitting all the details in my head when they're tricky or they
    > > change ever time I look at them. (Especially when I get distracted from one
    > > of those projects for 3-6 months and come back to find it changed.)

    >
    > I fully agree. However, I just gave away some ideas that I believe
    > they can make printk() easier and more understandable than it is right
    > now (for example, standardizing kprint_[registered,detected,...]
    > messages is something that I think it can simplify everyday use of
    > messages, both to people who has to code it, review/search the code
    > and people that reads the kernel output).
    >
    > >
    > > I recognize constantly having to learn new things as part of the cost of
    > > living, and making things more complicated happens as you add features. But
    > > when somebody reinvents the wheel it's really nice to have clearly spelled
    > > out the advantages of the new wheel vs the old one. It's nice for there to
    > > _be_ clear advantages, offsetting the increased complexity cost.

    >
    > I got your point, and I agree. However, I also see the possibilities
    > that a change of the logging API can bring: If someday it gets
    > improved, maybe such day should be improved as far as possible. This
    > kind of stuff that affect so many things are not going to change for
    > long periods of time, as you said.
    >
    > Still, I know some kind of changes can be really complex and maybe are
    > unproductive. I think the point is to get a middle point between new
    > complexity vs. new features.



    The beauty of printk is it's current simplicity. And even with that developers
    get it wrong. The changes seem like added complexity with little real gain.

    Plus none of the changes address the issue of getting better information.
    The kernel is already so noisy that most distributions boot with the quiet
    flag to shut it up. So less messages is probably better!

    > >
    > > In this case, upon asking, the only potential advantage here seems to be "now
    > > we can translate dmesg output into Chinese more easily", which is something

    >
    > Well, other improvements suggested are not just about internationalization.
    >
    > > you could already do in userspace already via regular expressions in a
    > > translating dmesg, and which has the primary effect of making the resulting
    > > dmesg useless to report to lkml without really improving the amount of sense
    > > it makes to nontechnical end users (who really aren't the target of the
    > > english dmesg output, either). The "linux developer who can't read english"
    > > niche is inherently somewhat problematic, as has been discussed here before.
    > >

    >
    > I didn't talk about internationalization (in fact, I think it is going
    > to be pretty complex to get it right and, worse, to get it up-to-date
    > in each release without error in translations)
    >
    > > The cost of this patch is making the kernel bigger, the in-kernel printk api
    > > more complicated, and the userspace dmesg noticeably more complex just to
    > > implement the same functionality against the new API. Documenting the
    > > changes is nice, but doesn't reduce this increase in complexity.
    > >
    > > The original idea (selectively compile out printk() instances based on log
    > > level to conserve space) is explicitly not addressed by this patch, and in
    > > fact this patch might actually make it harder to implement (by complicating
    > > the code).
    > >
    > > *shrug* That doesn't mean my objections are important to anyone else, just
    > > that I don't personally see any reason to be enthusiastic about this patch.

    >
    > Take a look to other suggested changes, maybe you like some of them
    > and you will have found a reason to be enthusiastic
    >
    > >
    > > Rob

    >



    --
    Stephen Hemminger
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  11. Re: [RFC][PATCH] New message-logging API (kprint)

    On 10/5/07, Rob Landley wrote:
    > The original idea (selectively compile out printk() instances based on log
    > level to conserve space) is explicitly not addressed by this patch, and in
    > fact this patch might actually make it harder to implement (by complicating
    > the code).


    This is wrong. The patch provides log-level-based filtering at compile
    time, effectively making the kernel smaller.

    > *shrug* That doesn't mean my objections are important to anyone else, just
    > that I don't personally see any reason to be enthusiastic about this patch.


    I agree; you are right about the other things, Maybe I can try to fit
    some of these things into printk itself (thanks for the tip, Alan),
    and we'll see how far we can get.

    Thanks.

    Vegard
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  12. Re: [RFC][PATCH] New message-logging API (kprint)

    On 10/6/07, Stephen Hemminger wrote:
    > On Sat, 6 Oct 2007 01:01:10 +0200
    > "Miguel Ojeda" wrote:
    >
    > > On 10/5/07, Rob Landley wrote:
    > > > On Friday 05 October 2007 2:01:08 am Miguel Ojeda wrote:
    > > > >
    > > > > I think we all are trying to give ideas to improve the current logging API.
    > > > >
    > > > > If something works, it's great; but it doesn't mean that it can't be
    > > > > improved, right?
    > > >
    > > > I'm all for improving the kernel, but my definition of "improved" does not
    > > > include every possible change. I balance "smaller and simpler" with "more
    > > > features". Complexity is a cost, we should get something in return.
    > > >
    > > > Making the same functionality simpler makes it "cheaper" from a development
    > > > standpoint. Smaller and simpler means less overhead, less to understand,
    > > > less to go wrong. It's also attractive to me personally, because I am a Bear
    > > > of Very Little Brain and between the dozen or so projects I try to follow, I
    > > > have trouble fitting all the details in my head when they're tricky or they
    > > > change ever time I look at them. (Especially when I get distracted from one
    > > > of those projects for 3-6 months and come back to find it changed.)

    > >
    > > I fully agree. However, I just gave away some ideas that I believe
    > > they can make printk() easier and more understandable than it is right
    > > now (for example, standardizing kprint_[registered,detected,...]
    > > messages is something that I think it can simplify everyday use of
    > > messages, both to people who has to code it, review/search the code
    > > and people that reads the kernel output).
    > >
    > > >
    > > > I recognize constantly having to learn new things as part of the cost of
    > > > living, and making things more complicated happens as you add features. But
    > > > when somebody reinvents the wheel it's really nice to have clearly spelled
    > > > out the advantages of the new wheel vs the old one. It's nice for there to
    > > > _be_ clear advantages, offsetting the increased complexity cost.

    > >
    > > I got your point, and I agree. However, I also see the possibilities
    > > that a change of the logging API can bring: If someday it gets
    > > improved, maybe such day should be improved as far as possible. This
    > > kind of stuff that affect so many things are not going to change for
    > > long periods of time, as you said.
    > >
    > > Still, I know some kind of changes can be really complex and maybe are
    > > unproductive. I think the point is to get a middle point between new
    > > complexity vs. new features.

    >
    >
    > The beauty of printk is it's current simplicity. And even with that developers
    > get it wrong. The changes seem like added complexity with little real gain.
    >
    > Plus none of the changes address the issue of getting better information.
    > The kernel is already so noisy that most distributions boot with the quiet
    > flag to shut it up. So less messages is probably better!
    >


    I agree. On the one hand, some changes are complex (like "blocks"
    implementation) and maybe they will not help at all. I'm not agreeing
    with every change

    On the other hand, the new tags (more standarized messages and
    simplified code) and all the information given by the new syslog
    retrieved from userspace (formatted messages => better information
    possibly) can do a lot of good (and maybe even more in the future,
    with a lot more stuff inside the kernel), without creating noise at
    boot at all. That kind of changes I think they would do more good than
    bad.

    --
    Miguel Ojeda
    http://maxextreme.googlepages.com/index.htm
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  13. Re: [RFC][PATCH] New message-logging API (kprint)

    On Friday 05 October 2007 6:01:10 pm Miguel Ojeda wrote:
    > > *shrug* That doesn't mean my objections are important to anyone else,
    > > just that I don't personally see any reason to be enthusiastic about this
    > > patch.

    >
    > Take a look to other suggested changes, maybe you like some of them
    > and you will have found a reason to be enthusiastic


    Is there any way to serialize the changes? It's hard to review a big lump.

    Rob
    --
    "One of my most productive days was throwing away 1000 lines of code."
    - Ken Thompson.
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  14. Re: [RFC][PATCH] New message-logging API (kprint)

    On Saturday 06 October 2007 1:10:26 am Vegard Nossum wrote:
    > On 10/5/07, Rob Landley wrote:
    > > The original idea (selectively compile out printk() instances based on
    > > log level to conserve space) is explicitly not addressed by this patch,
    > > and in fact this patch might actually make it harder to implement (by
    > > complicating the code).

    >
    > This is wrong. The patch provides log-level-based filtering at compile
    > time, effectively making the kernel smaller.


    I made it about halfway through the patch and the only compile time filtering
    I found was:

    --- a/drivers/md/md.c
    +++ b/drivers/md/md.c
    @@ -62,7 +62,10 @@
    *#define MdpMinorShift 6
    *
    *#define DEBUG 0
    -#define dprintk(x...) ((void)(DEBUG && printk(x)))
    +#define dprintk(x...)**********\
    +*******if(DEBUG) {*************\
    +*************** printk(x);*****\
    +*******}

    If you say it does, I'll take your word for it, but there's so much churn in
    there I didn't find it before my interest ran out...

    Rob
    --
    "One of my most productive days was throwing away 1000 lines of code."
    - Ken Thompson.
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  15. Re: [RFC][PATCH] New message-logging API (kprint)

    On Sun, 7 Oct 2007 16:56:01 -0500 Rob Landley wrote:

    > On Friday 05 October 2007 6:01:10 pm Miguel Ojeda wrote:
    > > > *shrug* That doesn't mean my objections are important to anyone else,
    > > > just that I don't personally see any reason to be enthusiastic about this
    > > > patch.

    > >
    > > Take a look to other suggested changes, maybe you like some of them
    > > and you will have found a reason to be enthusiastic

    >
    > Is there any way to serialize the changes? It's hard to review a big lump.


    There are also parts of the patch that could be submitted
    independently of any message-logging API changes.

    ---
    ~Randy
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  16. Re: [RFC][PATCH] New message-logging API (kprint)

    On Sun, 7 Oct 2007 16:50:49 -0500
    Rob Landley wrote:

    > On Saturday 06 October 2007 1:10:26 am Vegard Nossum wrote:
    > > On 10/5/07, Rob Landley wrote:
    > > > The original idea (selectively compile out printk() instances based on
    > > > log level to conserve space) is explicitly not addressed by this patch,
    > > > and in fact this patch might actually make it harder to implement (by
    > > > complicating the code).

    > >
    > > This is wrong. The patch provides log-level-based filtering at compile
    > > time, effectively making the kernel smaller.

    >
    > I made it about halfway through the patch and the only compile time filtering
    > I found was:
    >
    > --- a/drivers/md/md.c
    > +++ b/drivers/md/md.c
    > @@ -62,7 +62,10 @@
    > *#define MdpMinorShift 6
    > *
    > *#define DEBUG 0
    > -#define dprintk(x...) ((void)(DEBUG && printk(x)))
    > +#define dprintk(x...)**********\
    > +*******if(DEBUG) {*************\
    > +*************** printk(x);*****\
    > +*******}
    >
    > If you say it does, I'll take your word for it, but there's so much churn in
    > there I didn't find it before my interest ran out...
    >


    BTW that change might actually break code (dangling else problems).
    The original way was safer.

    --
    Stephen Hemminger
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  17. Re: [RFC][PATCH] New message-logging API (kprint)

    On 10/8/07, Stephen Hemminger wrote:
    > On Sun, 7 Oct 2007 16:50:49 -0500
    > Rob Landley wrote:
    >
    > > On Saturday 06 October 2007 1:10:26 am Vegard Nossum wrote:
    > > > On 10/5/07, Rob Landley wrote:

    > > I made it about halfway through the patch and the only compile time filtering
    > > I found was:
    > >
    > > --- a/drivers/md/md.c
    > > +++ b/drivers/md/md.c
    > > @@ -62,7 +62,10 @@
    > > #define MdpMinorShift 6
    > >
    > > #define DEBUG 0
    > > -#define dprintk(x...) ((void)(DEBUG && printk(x)))
    > > +#define dprintk(x...)\
    > > +if(DEBUG) {\
    > > + printk(x);\
    > > +}
    > >
    > > If you say it does, I'll take your word for it, but there's so much churn in
    > > there I didn't find it before my interest ran out...
    > >

    >
    > BTW that change might actually break code (dangling else problems).
    > The original way was safer.


    Yep, thanks. I think containing it in do {} while(0) should fix, though, no?

    Vegard
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  18. Re: [RFC][PATCH] New message-logging API (kprint)

    On Mon, 8 Oct 2007 17:33:53 +0200
    "Vegard Nossum" wrote:

    > On 10/8/07, Stephen Hemminger wrote:
    > > On Sun, 7 Oct 2007 16:50:49 -0500
    > > Rob Landley wrote:
    > >
    > > > On Saturday 06 October 2007 1:10:26 am Vegard Nossum wrote:
    > > > > On 10/5/07, Rob Landley wrote:
    > > > I made it about halfway through the patch and the only compile time filtering
    > > > I found was:
    > > >
    > > > --- a/drivers/md/md.c
    > > > +++ b/drivers/md/md.c
    > > > @@ -62,7 +62,10 @@
    > > > #define MdpMinorShift 6
    > > >
    > > > #define DEBUG 0
    > > > -#define dprintk(x...) ((void)(DEBUG && printk(x)))
    > > > +#define dprintk(x...)\
    > > > +if(DEBUG) {\
    > > > + printk(x);\
    > > > +}
    > > >
    > > > If you say it does, I'll take your word for it, but there's so much churn in
    > > > there I didn't find it before my interest ran out...
    > > >

    > >
    > > BTW that change might actually break code (dangling else problems).
    > > The original way was safer.

    >
    > Yep, thanks. I think containing it in do {} while(0) should fix, though, no?
    >
    > Vegard


    The correct fix is to just replace dprintk() with pr_debug()

    --
    Stephen Hemminger
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