The ftrace daemon is complex and error prone. This patch strips it out
of the code.

Signed-off-by: Steven Rostedt
---
kernel/trace/ftrace.c | 280 ++++--------------------------------------
kernel/trace/trace_selftest.c | 14 --
2 files changed, 28 insertions(+), 266 deletions(-)

Index: linux-compile.git/kernel/trace/ftrace.c
================================================== =================
--- linux-compile.git.orig/kernel/trace/ftrace.c 2008-10-22 16:07:29.000000000 -0400
+++ linux-compile.git/kernel/trace/ftrace.c 2008-10-22 16:07:36.000000000 -0400
@@ -165,21 +165,8 @@ static int __unregister_ftrace_function(
}

#ifdef CONFIG_DYNAMIC_FTRACE
-
#ifndef CONFIG_FTRACE_MCOUNT_RECORD
-/*
- * The hash lock is only needed when the recording of the mcount
- * callers are dynamic. That is, by the caller themselves and
- * not recorded via the compilation.
- */
-static DEFINE_SPINLOCK(ftrace_hash_lock);
-#define ftrace_hash_lock(flags) spin_lock_irqsave(&ftrace_hash_lock, flags)
-#define ftrace_hash_unlock(flags) \
- spin_unlock_irqrestore(&ftrace_hash_lock, flags)
-#else
-/* This is protected via the ftrace_lock with MCOUNT_RECORD. */
-#define ftrace_hash_lock(flags) do { (void)(flags); } while (0)
-#define ftrace_hash_unlock(flags) do { } while(0)
+# error Dynamic ftrace depends on MCOUNT_RECORD
#endif

/*
@@ -190,8 +177,6 @@ static DEFINE_SPINLOCK(ftrace_hash_lock)
*/
static unsigned long mcount_addr = MCOUNT_ADDR;

-static struct task_struct *ftraced_task;
-
enum {
FTRACE_ENABLE_CALLS = (1 << 0),
FTRACE_DISABLE_CALLS = (1 << 1),
@@ -208,7 +193,6 @@ static struct hlist_head ftrace_hash[FTR

static DEFINE_PER_CPU(int, ftrace_shutdown_disable_cpu);

-static DEFINE_MUTEX(ftraced_lock);
static DEFINE_MUTEX(ftrace_regex_lock);

struct ftrace_page {
@@ -226,10 +210,6 @@ struct ftrace_page {
static struct ftrace_page *ftrace_pages_start;
static struct ftrace_page *ftrace_pages;

-static int ftraced_trigger;
-static int ftraced_suspend;
-static int ftraced_stop;
-
static int ftrace_record_suspend;

static struct dyn_ftrace *ftrace_free_records;
@@ -393,7 +373,6 @@ static void
ftrace_record_ip(unsigned long ip)
{
struct dyn_ftrace *node;
- unsigned long flags;
unsigned long key;
int resched;
int cpu;
@@ -425,24 +404,18 @@ ftrace_record_ip(unsigned long ip)
if (ftrace_ip_in_hash(ip, key))
goto out;

- ftrace_hash_lock(flags);
-
/* This ip may have hit the hash before the lock */
if (ftrace_ip_in_hash(ip, key))
- goto out_unlock;
+ goto out;

node = ftrace_alloc_dyn_node(ip);
if (!node)
- goto out_unlock;
+ goto out;

node->ip = ip;

ftrace_add_hash(node, key);

- ftraced_trigger = 1;
-
- out_unlock:
- ftrace_hash_unlock(flags);
out:
per_cpu(ftrace_shutdown_disable_cpu, cpu)--;

@@ -642,7 +615,7 @@ ftrace_code_disable(struct dyn_ftrace *r
return 1;
}

-static int __ftrace_update_code(void *ignore);
+static int ftrace_update_code(void *ignore);

static int __ftrace_modify_code(void *data)
{
@@ -654,7 +627,7 @@ static int __ftrace_modify_code(void *da
* Update any recorded ips now that we have the
* machine stopped
*/
- __ftrace_update_code(NULL);
+ ftrace_update_code(NULL);
ftrace_replace_code(1);
tracing_on = 1;
} else if (*command & FTRACE_DISABLE_CALLS) {
@@ -681,26 +654,9 @@ static void ftrace_run_update_code(int c
stop_machine(__ftrace_modify_code, &command, NULL);
}

-void ftrace_disable_daemon(void)
-{
- /* Stop the daemon from calling kstop_machine */
- mutex_lock(&ftraced_lock);
- ftraced_stop = 1;
- mutex_unlock(&ftraced_lock);
-
- ftrace_force_update();
-}
-
-void ftrace_enable_daemon(void)
-{
- mutex_lock(&ftraced_lock);
- ftraced_stop = 0;
- mutex_unlock(&ftraced_lock);
-
- ftrace_force_update();
-}
-
static ftrace_func_t saved_ftrace_func;
+static int ftrace_start;
+static DEFINE_MUTEX(ftrace_start_lock);

static void ftrace_startup(void)
{
@@ -709,9 +665,9 @@ static void ftrace_startup(void)
if (unlikely(ftrace_disabled))
return;

- mutex_lock(&ftraced_lock);
- ftraced_suspend++;
- if (ftraced_suspend == 1)
+ mutex_lock(&ftrace_start_lock);
+ ftrace_start++;
+ if (ftrace_start == 1)
command |= FTRACE_ENABLE_CALLS;

if (saved_ftrace_func != ftrace_trace_function) {
@@ -724,7 +680,7 @@ static void ftrace_startup(void)

ftrace_run_update_code(command);
out:
- mutex_unlock(&ftraced_lock);
+ mutex_unlock(&ftrace_start_lock);
}

static void ftrace_shutdown(void)
@@ -734,9 +690,9 @@ static void ftrace_shutdown(void)
if (unlikely(ftrace_disabled))
return;

- mutex_lock(&ftraced_lock);
- ftraced_suspend--;
- if (!ftraced_suspend)
+ mutex_lock(&ftrace_start_lock);
+ ftrace_start--;
+ if (!ftrace_start)
command |= FTRACE_DISABLE_CALLS;

if (saved_ftrace_func != ftrace_trace_function) {
@@ -749,7 +705,7 @@ static void ftrace_shutdown(void)

ftrace_run_update_code(command);
out:
- mutex_unlock(&ftraced_lock);
+ mutex_unlock(&ftrace_start_lock);
}

static void ftrace_startup_sysctl(void)
@@ -759,15 +715,15 @@ static void ftrace_startup_sysctl(void)
if (unlikely(ftrace_disabled))
return;

- mutex_lock(&ftraced_lock);
+ mutex_lock(&ftrace_start_lock);
/* Force update next time */
saved_ftrace_func = NULL;
- /* ftraced_suspend is true if we want ftrace running */
- if (ftraced_suspend)
+ /* ftrace_start is true if we want ftrace running */
+ if (ftrace_start)
command |= FTRACE_ENABLE_CALLS;

ftrace_run_update_code(command);
- mutex_unlock(&ftraced_lock);
+ mutex_unlock(&ftrace_start_lock);
}

static void ftrace_shutdown_sysctl(void)
@@ -777,20 +733,20 @@ static void ftrace_shutdown_sysctl(void)
if (unlikely(ftrace_disabled))
return;

- mutex_lock(&ftraced_lock);
- /* ftraced_suspend is true if ftrace is running */
- if (ftraced_suspend)
+ mutex_lock(&ftrace_start_lock);
+ /* ftrace_start is true if ftrace is running */
+ if (ftrace_start)
command |= FTRACE_DISABLE_CALLS;

ftrace_run_update_code(command);
- mutex_unlock(&ftraced_lock);
+ mutex_unlock(&ftrace_start_lock);
}

static cycle_t ftrace_update_time;
static unsigned long ftrace_update_cnt;
unsigned long ftrace_update_tot_cnt;

-static int __ftrace_update_code(void *ignore)
+static int ftrace_update_code(void *ignore)
{
int i, save_ftrace_enabled;
cycle_t start, stop;
@@ -864,7 +820,6 @@ static int __ftrace_update_code(void *ig
stop = ftrace_now(raw_smp_processor_id());
ftrace_update_time = stop - start;
ftrace_update_tot_cnt += ftrace_update_cnt;
- ftraced_trigger = 0;

ftrace_enabled = save_ftrace_enabled;
ftrace_record_suspend--;
@@ -872,17 +827,6 @@ static int __ftrace_update_code(void *ig
return 0;
}

-static int ftrace_update_code(void)
-{
- if (unlikely(ftrace_disabled) ||
- !ftrace_enabled || !ftraced_trigger)
- return 0;
-
- stop_machine(__ftrace_update_code, NULL, NULL);
-
- return 1;
-}
-
static int __init ftrace_dyn_table_alloc(unsigned long num_to_init)
{
struct ftrace_page *pg;
@@ -1420,10 +1364,10 @@ ftrace_regex_release(struct inode *inode
}

mutex_lock(&ftrace_sysctl_lock);
- mutex_lock(&ftraced_lock);
- if (iter->filtered && ftraced_suspend && ftrace_enabled)
+ mutex_lock(&ftrace_start_lock);
+ if (iter->filtered && ftrace_start && ftrace_enabled)
ftrace_run_update_code(FTRACE_ENABLE_CALLS);
- mutex_unlock(&ftraced_lock);
+ mutex_unlock(&ftrace_start_lock);
mutex_unlock(&ftrace_sysctl_lock);

kfree(iter);
@@ -1443,55 +1387,6 @@ ftrace_notrace_release(struct inode *ino
return ftrace_regex_release(inode, file, 0);
}

-static ssize_t
-ftraced_read(struct file *filp, char __user *ubuf,
- size_t cnt, loff_t *ppos)
-{
- /* don't worry about races */
- char *buf = ftraced_stop ? "disabled\n" : "enabled\n";
- int r = strlen(buf);
-
- return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
-}
-
-static ssize_t
-ftraced_write(struct file *filp, const char __user *ubuf,
- size_t cnt, loff_t *ppos)
-{
- char buf[64];
- long val;
- int ret;
-
- if (cnt >= sizeof(buf))
- return -EINVAL;
-
- if (copy_from_user(&buf, ubuf, cnt))
- return -EFAULT;
-
- if (strncmp(buf, "enable", 6) == 0)
- val = 1;
- else if (strncmp(buf, "disable", 7) == 0)
- val = 0;
- else {
- buf[cnt] = 0;
-
- ret = strict_strtoul(buf, 10, &val);
- if (ret < 0)
- return ret;
-
- val = !!val;
- }
-
- if (val)
- ftrace_enable_daemon();
- else
- ftrace_disable_daemon();
-
- filp->f_pos += cnt;
-
- return cnt;
-}
-
static struct file_operations ftrace_avail_fops = {
.open = ftrace_avail_open,
.read = seq_read,
@@ -1522,38 +1417,6 @@ static struct file_operations ftrace_not
.release = ftrace_notrace_release,
};

-static struct file_operations ftraced_fops = {
- .open = tracing_open_generic,
- .read = ftraced_read,
- .write = ftraced_write,
-};
-
-/**
- * ftrace_force_update - force an update to all recording ftrace functions
- */
-int ftrace_force_update(void)
-{
- int ret = 0;
-
- if (unlikely(ftrace_disabled))
- return -ENODEV;
-
- mutex_lock(&ftrace_sysctl_lock);
- mutex_lock(&ftraced_lock);
-
- /*
- * If ftraced_trigger is not set, then there is nothing
- * to update.
- */
- if (ftraced_trigger && !ftrace_update_code())
- ret = -EBUSY;
-
- mutex_unlock(&ftraced_lock);
- mutex_unlock(&ftrace_sysctl_lock);
-
- return ret;
-}
-
static __init int ftrace_init_debugfs(void)
{
struct dentry *d_tracer;
@@ -1584,17 +1447,11 @@ static __init int ftrace_init_debugfs(vo
pr_warning("Could not create debugfs "
"'set_ftrace_notrace' entry\n");

- entry = debugfs_create_file("ftraced_enabled", 0644, d_tracer,
- NULL, &ftraced_fops);
- if (!entry)
- pr_warning("Could not create debugfs "
- "'ftraced_enabled' entry\n");
return 0;
}

fs_initcall(ftrace_init_debugfs);

-#ifdef CONFIG_FTRACE_MCOUNT_RECORD
static int ftrace_convert_nops(unsigned long *start,
unsigned long *end)
{
@@ -1614,7 +1471,7 @@ static int ftrace_convert_nops(unsigned

/* p is ignored */
local_irq_save(flags);
- __ftrace_update_code(p);
+ ftrace_update_code(p);
local_irq_restore(flags);

return 0;
@@ -1661,84 +1518,6 @@ void __init ftrace_init(void)
failed:
ftrace_disabled = 1;
}
-#else /* CONFIG_FTRACE_MCOUNT_RECORD */
-static int ftraced(void *ignore)
-{
- unsigned long usecs;
-
- while (!kthread_should_stop()) {
-
- set_current_state(TASK_INTERRUPTIBLE);
-
- /* check once a second */
- schedule_timeout(HZ);
-
- if (unlikely(ftrace_disabled))
- continue;
-
- mutex_lock(&ftrace_sysctl_lock);
- mutex_lock(&ftraced_lock);
- if (!ftraced_suspend && !ftraced_stop &&
- ftrace_update_code()) {
- usecs = nsecs_to_usecs(ftrace_update_time);
- if (ftrace_update_tot_cnt > 100000) {
- ftrace_update_tot_cnt = 0;
- pr_info("hm, dftrace overflow: %lu change%s"
- " (%lu total) in %lu usec%s\n",
- ftrace_update_cnt,
- ftrace_update_cnt != 1 ? "s" : "",
- ftrace_update_tot_cnt,
- usecs, usecs != 1 ? "s" : "");
- FTRACE_WARN_ON_ONCE(1);
- }
- }
- mutex_unlock(&ftraced_lock);
- mutex_unlock(&ftrace_sysctl_lock);
-
- ftrace_shutdown_replenish();
- }
- __set_current_state(TASK_RUNNING);
- return 0;
-}
-
-static int __init ftrace_dynamic_init(void)
-{
- struct task_struct *p;
- unsigned long addr;
- int ret;
-
- addr = (unsigned long)ftrace_record_ip;
-
- stop_machine(ftrace_dyn_arch_init, &addr, NULL);
-
- /* ftrace_dyn_arch_init places the return code in addr */
- if (addr) {
- ret = (int)addr;
- goto failed;
- }
-
- ret = ftrace_dyn_table_alloc(NR_TO_INIT);
- if (ret)
- goto failed;
-
- p = kthread_run(ftraced, NULL, "ftraced");
- if (IS_ERR(p)) {
- ret = -1;
- goto failed;
- }
-
- last_ftrace_enabled = ftrace_enabled = 1;
- ftraced_task = p;
-
- return 0;
-
- failed:
- ftrace_disabled = 1;
- return ret;
-}
-
-core_initcall(ftrace_dynamic_init);
-#endif /* CONFIG_FTRACE_MCOUNT_RECORD */

#else
# define ftrace_startup() do { } while (0)
@@ -1758,9 +1537,6 @@ void ftrace_kill(void)
{
ftrace_disabled = 1;
ftrace_enabled = 0;
-#ifdef CONFIG_DYNAMIC_FTRACE
- ftraced_suspend = -1;
-#endif
clear_ftrace_function();
}

Index: linux-compile.git/kernel/trace/trace_selftest.c
================================================== =================
--- linux-compile.git.orig/kernel/trace/trace_selftest.c 2008-10-22 15:09:03.000000000 -0400
+++ linux-compile.git/kernel/trace/trace_selftest.c 2008-10-22 16:07:36.000000000 -0400
@@ -99,13 +99,6 @@ int trace_selftest_startup_dynamic_traci
/* passed in by parameter to fool gcc from optimizing */
func();

- /* update the records */
- ret = ftrace_force_update();
- if (ret) {
- printk(KERN_CONT ".. ftraced failed .. ");
- return ret;
- }
-
/*
* Some archs *cough*PowerPC*cough* add charachters to the
* start of the function names. We simply put a '*' to
@@ -183,13 +176,6 @@ trace_selftest_startup_function(struct t
/* make sure msleep has been recorded */
msleep(1);

- /* force the recorded functions to be traced */
- ret = ftrace_force_update();
- if (ret) {
- printk(KERN_CONT ".. ftraced failed .. ");
- return ret;
- }
-
/* start the tracing */
ftrace_enabled = 1;
tracer_enabled = 1;

--
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