lkml.org 
[lkml]   [2013]   [Jan]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[ 027/221] watchdog: Fix disable/enable regression
    Date
    3.7-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Bjørn Mork <bjorn@mork.no>

    commit 3935e89505a1c3ab3f3b0c7ef0eae54124f48905 upstream.

    Commit 8d4516904b39 ("watchdog: Fix CPU hotplug regression") causes an
    oops or hard lockup when doing

    echo 0 > /proc/sys/kernel/nmi_watchdog
    echo 1 > /proc/sys/kernel/nmi_watchdog

    and the kernel is booted with nmi_watchdog=1 (default)

    Running laptop-mode-tools and disconnecting/connecting AC power will
    cause this to trigger, making it a common failure scenario on laptops.

    Instead of bailing out of watchdog_disable() when !watchdog_enabled we
    can initialize the hrtimer regardless of watchdog_enabled status. This
    makes it safe to call watchdog_disable() in the nmi_watchdog=0 case,
    without the negative effect on the enabled => disabled => enabled case.

    All these tests pass with this patch:
    - nmi_watchdog=1
    echo 0 > /proc/sys/kernel/nmi_watchdog
    echo 1 > /proc/sys/kernel/nmi_watchdog

    - nmi_watchdog=0
    echo 0 > /sys/devices/system/cpu/cpu1/online

    - nmi_watchdog=0
    echo mem > /sys/power/state

    Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=51661

    Signed-off-by: Bjørn Mork <bjorn@mork.no>
    Cc: Norbert Warmuth <nwarmuth@t-online.de>
    Cc: Joseph Salisbury <joseph.salisbury@canonical.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    kernel/watchdog.c | 11 ++++-------
    1 file changed, 4 insertions(+), 7 deletions(-)

    --- a/kernel/watchdog.c
    +++ b/kernel/watchdog.c
    @@ -343,6 +343,10 @@ static void watchdog_enable(unsigned int
    {
    struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);

    + /* kick off the timer for the hardlockup detector */
    + hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
    + hrtimer->function = watchdog_timer_fn;
    +
    if (!watchdog_enabled) {
    kthread_park(current);
    return;
    @@ -351,10 +355,6 @@ static void watchdog_enable(unsigned int
    /* Enable the perf event */
    watchdog_nmi_enable(cpu);

    - /* kick off the timer for the hardlockup detector */
    - hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
    - hrtimer->function = watchdog_timer_fn;
    -
    /* done here because hrtimer_start can only pin to smp_processor_id() */
    hrtimer_start(hrtimer, ns_to_ktime(get_sample_period()),
    HRTIMER_MODE_REL_PINNED);
    @@ -368,9 +368,6 @@ static void watchdog_disable(unsigned in
    {
    struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);

    - if (!watchdog_enabled)
    - return;
    -
    watchdog_set_prio(SCHED_NORMAL, 0);
    hrtimer_cancel(hrtimer);
    /* disable the perf event */

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2013-01-15 20:42    [W:4.159 / U:0.036 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site