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hrtimers: Move SMP function call to thread context

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commit 5ec2481b7b 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>
This commit is contained in:
Thomas Gleixner
2013-07-05 12:09:18 +02:00
committed by Greg Kroah-Hartman
parent c4d98e2535
commit 2d06fa0f82
1 changed files with 13 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
kernel/hrtimer.c
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@@ -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();
}