Messages in this thread Patch in this message | | | From | Luis Henriques <> | Subject | [PATCH 106/106] hrtimers: Move SMP function call to thread context | Date | Tue, 30 Jul 2013 10:32:05 +0100 |
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3.5.7.18 -stable review patch. If anyone has any objections, please let me know.
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From: Thomas Gleixner <tglx@linutronix.de>
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 Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [ luis: backported to 3.5: adjusted context ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- kernel/hrtimer.c | 28 +++++++++++++--------------- 1 file changed, 13 insertions(+), 15 deletions(-)
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index 60f7e32..a57ef25 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -707,17 +707,20 @@ 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 @@ -766,8 +769,10 @@ 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) @@ -1416,13 +1421,6 @@ 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(); } -- 1.8.3.2
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