[PATCH 1/3] [RFC] hrtimer: Fix clock_was_set so it is safe to call from atomic
From: John Stultz <hidden>
Date: 2012-07-03 02:17:47
Also in:
lkml
Subsystem:
the rest · Maintainer:
Linus Torvalds
NOTE:This is a prerequisite patch that's required to address the widely observed leap-second related futex/hrtimer issues. Currently clock_was_set() is unsafe to be called from atomic context, as it calls on_each_cpu(). This causes problems when we need to adjust the time from update_wall_time(). To fix this, if clock_was_set is called we're in_atomic, we schedule a timer to fire for immedately after we're out of interrupt context to then notify the hrtimer subsystem. CC: Prarit Bhargava <redacted> CC: stable@vger.kernel.org CC: Thomas Gleixner <redacted> Reported-by: Jan Engelhardt <redacted> Signed-off-by: John Stultz <redacted> --- kernel/hrtimer.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index ae34bf5..393fd4d 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c@@ -746,7 +746,7 @@ static inline void retrigger_next_event(void *arg) { } * resolution timer interrupts. On UP we just disable interrupts and * call the high resolution interrupt code. */ -void clock_was_set(void) +static void do_clock_was_set(unsigned long data) { #ifdef CONFIG_HIGH_RES_TIMERS /* Retrigger the CPU local events everywhere */
@@ -755,6 +755,21 @@ void clock_was_set(void) timerfd_clock_was_set(); } +static struct timer_list clock_was_set_timer; + +void clock_was_set(void) +{ + /* + * We can't call on_each_cpu() from atomic context, + * so if we're in_atomic, schedule the clock_was_set + * via a timer_list timer for right after. + */ + if (in_atomic()) + mod_timer(&clock_was_set_timer, jiffies); + else + do_clock_was_set(0); +} + /* * During resume we might have to reprogram the high resolution timer * interrupt (on the local CPU):
@@ -1152,6 +1167,8 @@ static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id, base = hrtimer_clockid_to_base(clock_id); timer->base = &cpu_base->clock_base[base]; timerqueue_init(&timer->node); + init_timer(&clock_was_set_timer); + clock_was_set_timer.function = do_clock_was_set; #ifdef CONFIG_TIMER_STATS timer->start_site = NULL;
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1.7.9.5