3.16.80-rc1 review patch. If anyone has any objections, please let me know.
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From: Viresh Kumar viresh.kumar@linaro.org
commit cddd02489f52ccf635ed65931214729a23b93cd6 upstream.
In lowres mode, hrtimers are serviced by the tick instead of a clock event. Now it works well as long as the tick stays periodic but we must also make sure that the hrtimers are serviced in dynticks mode.
Part of that job consist in kicking a dynticks hrtimer target in order to make it reconsider the next tick to schedule to correctly handle the hrtimer's expiring time. And that part isn't handled by the hrtimers subsystem.
To prepare for fixing this, we need __hrtimer_start_range_ns() to be able to resolve the CPU target associated to a hrtimer's object 'cpu_base' so that the kick can be centralized there.
So lets store it in the 'struct hrtimer_cpu_base' to resolve the CPU without overhead. It is set once at CPU's online notification.
Signed-off-by: Viresh Kumar viresh.kumar@linaro.org Signed-off-by: Frederic Weisbecker fweisbec@gmail.com Link: http://lkml.kernel.org/r/1403393357-2070-4-git-send-email-fweisbec@gmail.com Signed-off-by: Thomas Gleixner tglx@linutronix.de [bwh: Backported to 3.16 as dependency of commit b9023b91dd02 "tick: broadcast-hrtimer: Fix a race in bc_set_next": - Adjust filename, context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- include/linux/hrtimer.h | 2 ++ kernel/hrtimer.c | 1 + 2 files changed, 3 insertions(+)
--- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -165,6 +165,7 @@ enum hrtimer_base_type { * struct hrtimer_cpu_base - the per cpu clock bases * @lock: lock protecting the base and associated clock bases * and timers + * @cpu: cpu number * @active_bases: Bitfield to mark bases with active timers * @clock_was_set: Indicates that clock was set from irq context. * @expires_next: absolute time of the next event which was scheduled @@ -179,6 +180,7 @@ enum hrtimer_base_type { */ struct hrtimer_cpu_base { raw_spinlock_t lock; + unsigned int cpu; unsigned int active_bases; unsigned int clock_was_set; #ifdef CONFIG_HIGH_RES_TIMERS --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -1687,6 +1687,7 @@ static void init_hrtimers_cpu(int cpu) }
cpu_base->active_bases = 0; + cpu_base->cpu = cpu; hrtimer_init_hres(cpu_base); }