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    Subject[PATCH] Wait to remove active timer when rescheduling hrtimer
    In the current hrtimer implementation, when explicitly
    removing a timer, the hrtimer_cancel function waits
    until the timer is not currently running before actually
    calling remove_hrtimer. But in the __hrtimer_start_range_ns
    function (called by hrtimer_start, among others), it
    calls remove_hrtimer without checking to see if the
    timer is currently running. This doesn't seem to cause
    much trouble in the vanilla kernel, but in the -RT
    kernel, this causes a silent hang when exercising the
    sch_htb module on a 10GbE interface.

    Signed-off-by: Vernon Mauery <>
    kernel/hrtimer.c | 5 +++++
    1 files changed, 5 insertions(+), 0 deletions(-)

    diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
    index 0c8d7c0..c7e8ba0 100644
    --- a/kernel/hrtimer.c
    +++ b/kernel/hrtimer.c
    @@ -935,6 +935,11 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
    base = lock_hrtimer_base(timer, &flags);

    /* Remove an active timer from the queue: */
    + while (hrtimer_callback_running(timer)) {
    + unlock_hrtimer_base(timer, &flags);
    + hrtimer_wait_for_timer(timer);
    + base = lock_hrtimer_base(timer, &flags);
    + }
    ret = remove_hrtimer(timer, base);

    /* Switch the timer base, if necessary: */

     \ /
      Last update: 2011-01-21 18:55    [W:0.019 / U:1.644 seconds]
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