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authorAnna-Maria Gleixner <anna-maria@linutronix.de>2017-12-21 11:41:45 +0100
committerIngo Molnar <mingo@kernel.org>2018-01-16 02:35:47 +0100
commiteb27926ba05233dc4f2052cc9d4f19359ec3cd2c (patch)
tree4a71a00143becb669314ce5ace3fd1c06ae04e60 /kernel/time/hrtimer.c
parent07a9a7eae86abb796468b225586086d7c4cb59fc (diff)
hrtimer: Make hrtimer_cpu_base.next_timer handling unconditional
hrtimer_cpu_base.next_timer stores the pointer to the next expiring timer in a CPU base. This pointer cannot be dereferenced and is solely used to check whether a hrtimer which is removed is the hrtimer which is the first to expire in the CPU base. If this is the case, then the timer hardware needs to be reprogrammed to avoid an extra interrupt for nothing. Again, this is conditional functionality, but there is no compelling reason to make this conditional. As a preparation, hrtimer_cpu_base.next_timer needs to be available unconditonally. Aside of that the upcoming support for softirq based hrtimers requires access to this pointer unconditionally as well, so our motivation is not entirely simplicity based. Make the update of hrtimer_cpu_base.next_timer unconditional and remove the #ifdef cruft. The impact on CONFIG_HIGH_RES_TIMERS=n && CONFIG_NOHZ=n is marginal as it's just a store on an already dirtied cacheline. No functional change. Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Cc: Christoph Hellwig <hch@lst.de> Cc: John Stultz <john.stultz@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: keescook@chromium.org Link: http://lkml.kernel.org/r/20171221104205.7269-17-anna-maria@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/time/hrtimer.c')
-rw-r--r--kernel/time/hrtimer.c12
1 files changed, 2 insertions, 10 deletions
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index a9ab67f3e5d5..26abaa7b0419 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -459,21 +459,13 @@ __next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
while ((base = __next_base((cpu_base), &(active))))
#if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS)
-static inline void hrtimer_update_next_timer(struct hrtimer_cpu_base *cpu_base,
- struct hrtimer *timer)
-{
-#ifdef CONFIG_HIGH_RES_TIMERS
- cpu_base->next_timer = timer;
-#endif
-}
-
static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base)
{
struct hrtimer_clock_base *base;
unsigned int active = cpu_base->active_bases;
ktime_t expires, expires_next = KTIME_MAX;
- hrtimer_update_next_timer(cpu_base, NULL);
+ cpu_base->next_timer = NULL;
for_each_active_base(base, cpu_base, active) {
struct timerqueue_node *next;
struct hrtimer *timer;
@@ -483,7 +475,7 @@ static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base)
expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
if (expires < expires_next) {
expires_next = expires;
- hrtimer_update_next_timer(cpu_base, timer);
+ cpu_base->next_timer = timer;
}
}
/*