On Thu, 18 Jul 2013, Greg KH wrote:
> On Thu, Jul 18, 2013 at 03:57:26PM +0800, Zhouping Liu wrote:
> > On 07/18/2013 01:00 PM, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
> > > The patch below does not apply to the 3.10-stable tree.
> > > If someone wants it applied there, or to any other stable or longterm
> > > tree, then please email the backport, including the original git commit
> > > id to <stable@xxxxxxxxxxxxxxx>.
> >
> > Hi Greg,
> >
> > Its prerequisite patch is:
> > 7c4c3a0f18b hrtimers: Support resuming with two or more CPUs online (but
> > stopped)
> > how about also back-port this patch?
>
> I could do that, but from reading the changelog comments below, is this
> patch really needed for 3.10-stable? 3.11 seems to make sense, as some
> other code was using this api and causing problems, but that isn't in
> 3.10 from what I can tell, right?
>
> So, is it really needed for 3.10?
The issue itself (smp function call from softirq context) needs to be
fixed in older kernels as well. Backport w/o the XEN dependency below.
Thanks,
tglx
Index: linux-2.6/kernel/hrtimer.c
===================================================================
--- linux-2.6.orig/kernel/hrtimer.c
+++ linux-2.6/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();
}
--
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