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authorThomas Gleixner <tglx@linutronix.de>2013-07-05 12:09:18 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-07-28 16:30:22 -0700
commit2d06fa0f825ec1d7943a3bcceecbd85aa82ef27d (patch)
treea94823276431964d5c6de69a386bfb74aa8dcadf
parentc4d98e2535e0269fcd513cbb79e937ef3ccc3d01 (diff)
downloadlwn-2d06fa0f825ec1d7943a3bcceecbd85aa82ef27d.tar.gz
lwn-2d06fa0f825ec1d7943a3bcceecbd85aa82ef27d.zip
hrtimers: Move SMP function call to thread context
commit 5ec2481b7b47a4005bb446d176e5d0257400c77d upstream. smp_call_function_* must not be called from softirq context. But clock_was_set() which calls on_each_cpu() is called from softirq context to implement a delayed clock_was_set() for the timer interrupt handler. Though that almost never gets invoked. A recent change in the resume code uses the softirq based delayed clock_was_set to support Xens resume mechanism. linux-next contains a new warning which warns if smp_call_function_* is called from softirq context which gets triggered by that Xen change. Fix this by moving the delayed clock_was_set() call to a work context. Reported-and-tested-by: Artem Savkov <artem.savkov@gmail.com> Reported-by: Sasha Levin <sasha.levin@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: H. Peter Anvin <hpa@zytor.com>, Cc: Konrad Wilk <konrad.wilk@oracle.com> Cc: John Stultz <john.stultz@linaro.org> Cc: xen-devel@lists.xen.org Cc: stable@vger.kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--kernel/hrtimer.c28
1 files changed, 13 insertions, 15 deletions
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index fd4b13b131f8..2288fbdada16 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -721,17 +721,20 @@ static int hrtimer_switch_to_hres(void)
return 1;
}
+static void clock_was_set_work(struct work_struct *work)
+{
+ clock_was_set();
+}
+
+static DECLARE_WORK(hrtimer_work, clock_was_set_work);
+
/*
- * Called from timekeeping code to reprogramm the hrtimer interrupt
- * device. If called from the timer interrupt context we defer it to
- * softirq context.
+ * Called from timekeeping and resume code to reprogramm the hrtimer
+ * interrupt device on all cpus.
*/
void clock_was_set_delayed(void)
{
- struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
-
- cpu_base->clock_was_set = 1;
- __raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+ schedule_work(&hrtimer_work);
}
#else
@@ -780,8 +783,10 @@ void hrtimers_resume(void)
WARN_ONCE(!irqs_disabled(),
KERN_INFO "hrtimers_resume() called with IRQs enabled!");
+ /* Retrigger on the local CPU */
retrigger_next_event(NULL);
- timerfd_clock_was_set();
+ /* And schedule a retrigger for all others */
+ clock_was_set_delayed();
}
static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
@@ -1432,13 +1437,6 @@ void hrtimer_peek_ahead_timers(void)
static void run_hrtimer_softirq(struct softirq_action *h)
{
- struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
-
- if (cpu_base->clock_was_set) {
- cpu_base->clock_was_set = 0;
- clock_was_set();
- }
-
hrtimer_peek_ahead_timers();
}