[RFC PATCH] Check if the Hangcheck-timer TSC source is stable - Kernel

This is a discussion on [RFC PATCH] Check if the Hangcheck-timer TSC source is stable - Kernel ; Check if the TSC source is stable otherwise fail registration. Signed-off-by: Michael Trimarchi --- diff --git a/drivers/char/hangcheck-timer.c b/drivers/char/hangcheck-timer.c index 712d9f2..910a77a 100644 --- a/drivers/char/hangcheck-timer.c +++ b/drivers/char/hangcheck-timer.c @@ -10,12 +10,12 @@ * This program is free software; you can redistribute it and/or ...

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Thread: [RFC PATCH] Check if the Hangcheck-timer TSC source is stable

  1. [RFC PATCH] Check if the Hangcheck-timer TSC source is stable



    Check if the TSC source is stable otherwise fail registration.

    Signed-off-by: Michael Trimarchi

    ---
    diff --git a/drivers/char/hangcheck-timer.c b/drivers/char/hangcheck-timer.c
    index 712d9f2..910a77a 100644
    --- a/drivers/char/hangcheck-timer.c
    +++ b/drivers/char/hangcheck-timer.c
    @@ -10,12 +10,12 @@
    * This program is free software; you can redistribute it and/or
    * modify it under the terms of the GNU General Public
    * License version 2 as published by the Free Software Foundation.
    - *
    + *
    * This program is distributed in the hope that it will be useful,
    * but WITHOUT ANY WARRANTY; without even the implied warranty of
    * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    * General Public License for more details.
    - *
    + *
    * You should have received a copy of the GNU General Public
    * License along with this program; if not, write to the
    * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
    @@ -64,14 +64,18 @@ static int hangcheck_dump_tasks; /* Defaults to not dumping SysRQ T */
    module_param(hangcheck_tick, int, 0);
    MODULE_PARM_DESC(hangcheck_tick, "Timer delay.");
    module_param(hangcheck_margin, int, 0);
    -MODULE_PARM_DESC(hangcheck_margin, "If the hangcheck timer has been delayed more than hangcheck_margin seconds, the driver will fire.");
    +MODULE_PARM_DESC(hangcheck_margin, "If the hangcheck timer has been delayed"
    + " more than hangcheck_margin seconds, the driver will fire.");
    module_param(hangcheck_reboot, int, 0);
    -MODULE_PARM_DESC(hangcheck_reboot, "If nonzero, the machine will reboot when the timer margin is exceeded.");
    +MODULE_PARM_DESC(hangcheck_reboot, "If nonzero, the machine will reboot"
    + " when the timer margin is exceeded.");
    module_param(hangcheck_dump_tasks, int, 0);
    -MODULE_PARM_DESC(hangcheck_dump_tasks, "If nonzero, the machine will dump the system task state when the timer margin is exceeded.");
    +MODULE_PARM_DESC(hangcheck_dump_tasks, "If nonzero, the machine will dump"
    + " the system task state when the timer margin is exceeded.");

    MODULE_AUTHOR("Oracle");
    -MODULE_DESCRIPTION("Hangcheck-timer detects when the system has gone out to lunch past a certain margin.");
    +MODULE_DESCRIPTION("Hangcheck-timer detects when the system has gone"
    + " out to lunch past a certain margin.");
    MODULE_LICENSE("GPL");
    MODULE_VERSION(VERSION_STR);

    @@ -81,7 +85,7 @@ MODULE_VERSION(VERSION_STR);
    static int __init hangcheck_parse_tick(char *str)
    {
    int par;
    - if (get_option(&str,&par))
    + if (get_option(&str, &par))
    hangcheck_tick = par;
    return 1;
    }
    @@ -89,7 +93,7 @@ static int __init hangcheck_parse_tick(char *str)
    static int __init hangcheck_parse_margin(char *str)
    {
    int par;
    - if (get_option(&str,&par))
    + if (get_option(&str, &par))
    hangcheck_margin = par;
    return 1;
    }
    @@ -97,7 +101,7 @@ static int __init hangcheck_parse_margin(char *str)
    static int __init hangcheck_parse_reboot(char *str)
    {
    int par;
    - if (get_option(&str,&par))
    + if (get_option(&str, &par))
    hangcheck_reboot = par;
    return 1;
    }
    @@ -105,7 +109,7 @@ static int __init hangcheck_parse_reboot(char *str)
    static int __init hangcheck_parse_dump_tasks(char *str)
    {
    int par;
    - if (get_option(&str,&par))
    + if (get_option(&str, &par))
    hangcheck_dump_tasks = par;
    return 1;
    }
    @@ -151,8 +155,10 @@ static void hangcheck_fire(unsigned long data)

    if (cur_tsc > hangcheck_tsc)
    tsc_diff = cur_tsc - hangcheck_tsc;
    - else
    - tsc_diff = (cur_tsc + (~0ULL - hangcheck_tsc)); /* or something */
    + else {
    + /* or samenthing */
    + tsc_diff = (cur_tsc + (~0ULL - hangcheck_tsc));
    + }

    if (tsc_diff > hangcheck_tsc_margin) {
    if (hangcheck_dump_tasks) {
    @@ -172,15 +178,21 @@ static void hangcheck_fire(unsigned long data)
    hangcheck_tsc = monotonic_clock();
    }

    -
    static int __init hangcheck_init(void)
    {
    - printk("Hangcheck: starting hangcheck timer %s (tick is %d seconds, margin is %d seconds).\n",
    + printk(KERN_INFO "Hangcheck: starting hangcheck timer %s"
    + " (tick is %d seconds, margin is %d seconds).\n",
    VERSION_STR, hangcheck_tick, hangcheck_margin);
    -#if defined (HAVE_MONOTONIC)
    - printk("Hangcheck: Using monotonic_clock().\n");
    +#if defined(HAVE_MONOTONIC)
    + printk(KERN_INFO "Hangcheck: Using monotonic_clock().\n");
    #else
    - printk("Hangcheck: Using get_cycles().\n");
    + if (!check_tsc_unstable())
    + printk(KERN_INFO "Hangcheck: Using get_cycles().\n");
    + else {
    + printk(KERN_ERR "Handcheck: Failed to register"
    + " (Unstable TSC).\n");
    + return -ENODEV;
    + }
    #endif /* HAVE_MONOTONIC */
    hangcheck_tsc_margin =
    (unsigned long long)(hangcheck_margin + hangcheck_tick);
    @@ -196,7 +208,7 @@ static int __init hangcheck_init(void)
    static void __exit hangcheck_exit(void)
    {
    del_timer_sync(&hangcheck_ticktock);
    - printk("Hangcheck: Stopped hangcheck timer.\n");
    + printk(KERN_INFO "Hangcheck: Stopped hangcheck timer.\n");
    }

    module_init(hangcheck_init);


  2. Re: [RFC PATCH] Check if the Hangcheck-timer TSC source is stable

    On Thu, Nov 06, 2008 at 11:37:28PM +0100, Michael Trimarchi wrote:
    > Check if the TSC source is stable otherwise fail registration.


    Good idea.

    > @@ -151,8 +155,10 @@ static void hangcheck_fire(unsigned long data)
    >
    > if (cur_tsc > hangcheck_tsc)
    > tsc_diff = cur_tsc - hangcheck_tsc;
    > - else
    > - tsc_diff = (cur_tsc + (~0ULL - hangcheck_tsc)); /* or something */
    > + else {
    > + /* or samenthing */
    > + tsc_diff = (cur_tsc + (~0ULL - hangcheck_tsc));
    > + }


    This hunk isn't any good. The comment spelling is messed up,
    and really you can just remove the "or something".

    Joel

    --

    "There is no sincerer love than the love of food."
    - George Bernard Shaw

    Joel Becker
    Principal Software Developer
    Oracle
    E-mail: joel.becker@oracle.com
    Phone: (650) 506-8127
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  3. Re: [RFC PATCH V2] Check if the Hangcheck-timer TSC source is stable



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