Commit-ID: de907e8432b08f2d5966c36e0747e97c0e596810 Gitweb: http://git.kernel.org/tip/de907e8432b08f2d5966c36e0747e97c0e596810 Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx> AuthorDate: Thu, 9 Jul 2009 13:52:32 +0200 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitDate: Thu, 9 Jul 2009 13:59:11 +0200 hrtimer: migration: do not check expiry time on current CPU The timer migration code needs to check whether the expiry time of the timer is before the programmed clock event expiry time when the timer is enqueued on another CPU because we can not reprogram the timer device on the other CPU. The current logic checks the expiry time even if we enqueue on the current CPU when nohz_get_load_balancer() returns current CPU. This might lead to an endless loop in the expiry check code when the expiry time of the timer is before the current programmed next event. Check whether nohz_get_load_balancer() returns current CPU and skip the expiry check if this is the case. Cc: Arun Bharadwaj <arun@xxxxxxxxxxxxxxxxxx LKML-Reference: <new-submission> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> --- kernel/hrtimer.c | 15 +++++++++++++-- 1 files changed, 13 insertions(+), 2 deletions(-) diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index 0d43451..d171ecf 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -206,8 +206,19 @@ switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base, #if defined(CONFIG_NO_HZ) && defined(CONFIG_SMP) if (!pinned && get_sysctl_timer_migration() && idle_cpu(cpu)) { preferred_cpu = get_nohz_load_balancer(); - if (preferred_cpu >= 0) - cpu = preferred_cpu; + if (preferred_cpu >= 0) { + /* + * We must not check the expiry value when + * preferred_cpu is the current cpu. If base + * != new_base we would loop forever when the + * timer expires before the current programmed + * next timer event. + */ + if (preferred_cpu != cpu) + cpu = preferred_cpu; + else + preferred_cpu = -1; + } } #endif -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html