@@ -640,21 +640,9 @@ static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
* and expiry check is done in the hrtimer_interrupt or in the softirq.
*/
static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
- struct hrtimer_clock_base *base,
- int wakeup)
+ struct hrtimer_clock_base *base)
{
- if (base->cpu_base->hres_active && hrtimer_reprogram(timer, base)) {
- if (wakeup) {
- raw_spin_unlock(&base->cpu_base->lock);
- raise_softirq_irqoff(HRTIMER_SOFTIRQ);
- raw_spin_lock(&base->cpu_base->lock);
- } else
- __raise_softirq_irqoff(HRTIMER_SOFTIRQ);
-
- return 1;
- }
-
- return 0;
+ return base->cpu_base->hres_active && hrtimer_reprogram(timer, base);
}
static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
@@ -735,8 +723,7 @@ static inline int hrtimer_switch_to_hres(void) { return 0; }
static inline void
hrtimer_force_reprogram(struct hrtimer_cpu_base *base, int skip_equal) { }
static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
- struct hrtimer_clock_base *base,
- int wakeup)
+ struct hrtimer_clock_base *base)
{
return 0;
}
@@ -995,8 +982,21 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
*
* XXX send_remote_softirq() ?
*/
- if (leftmost && new_base->cpu_base == &__get_cpu_var(hrtimer_bases))
- hrtimer_enqueue_reprogram(timer, new_base, wakeup);
+ if (leftmost && new_base->cpu_base == &__get_cpu_var(hrtimer_bases)
+ && hrtimer_enqueue_reprogram(timer, new_base)) {
+ if (wakeup) {
+ /*
+ * We need to drop cpu_base->lock to avoid a
+ * lock ordering issue vs. rq->lock.
+ */
+ raw_spin_unlock(&new_base->cpu_base->lock);
+ raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+ local_irq_restore(flags);
+ return ret;
+ } else {
+ __raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+ }
+ }
unlock_hrtimer_base(timer, &flags);
This is a note to let you know that I have just added a patch titled hrtimer: Prevent hrtimer_enqueue_reprogram race to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 233c19c09303a2284c03824b18b71b476154739d Mon Sep 17 00:00:00 2001 From: Leonid Shatz <leonid.shatz@ravellosystems.com> Date: Mon, 4 Feb 2013 14:33:37 +0200 Subject: [PATCH] hrtimer: Prevent hrtimer_enqueue_reprogram race commit b22affe0aef429d657bc6505aacb1c569340ddd2 upstream. hrtimer_enqueue_reprogram contains a race which could result in timer.base switch during unlock/lock sequence. hrtimer_enqueue_reprogram is releasing the lock protecting the timer base for calling raise_softirq_irqsoff() due to a lock ordering issue versus rq->lock. If during that time another CPU calls __hrtimer_start_range_ns() on the same hrtimer, the timer base might switch, before the current CPU can lock base->lock again and therefor the unlock_timer_base() call will unlock the wrong lock. [ tglx: Added comment and massaged changelog ] Signed-off-by: Leonid Shatz <leonid.shatz@ravellosystems.com> Signed-off-by: Izik Eidus <izik.eidus@ravellosystems.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Link: http://lkml.kernel.org/r/1359981217-389-1-git-send-email-izik.eidus@ravellosystems.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- kernel/hrtimer.c | 36 ++++++++++++++++++------------------ 1 file changed, 18 insertions(+), 18 deletions(-) -- 1.8.1.2