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timerfd: Provide timerfd_resume()

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Resuming timekeeping is a clock-was-set event and uses the clock-was-set
notification mechanism. This is in the way of making the clock-was-set
update for hrtimers selective so unnecessary IPIs are avoided when a CPU
base does not have timers queued which are affected by the clock setting.

Provide a seperate timerfd_resume() interface so the resume logic and the
clock-was-set mechanism can be distangled in the core code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210713135158.395287410@linutronix.de
This commit is contained in:
Thomas Gleixner 2021-07-13 15:39:50 +02:00
parent e71a4153b7
commit 66f7b0c8aa
2 changed files with 18 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

16
fs/timerfd.c
View file

@ -115,6 +115,22 @@ void timerfd_clock_was_set(void)
rcu_read_unlock(); rcu_read_unlock();
} }
static void timerfd_resume_work(struct work_struct *work)
{
timerfd_clock_was_set();
}
static DECLARE_WORK(timerfd_work, timerfd_resume_work);
/*
* Invoked from timekeeping_resume(). Defer the actual update to work so
* timerfd_clock_was_set() runs in task context.
*/
void timerfd_resume(void)
{
schedule_work(&timerfd_work);
}
static void __timerfd_remove_cancel(struct timerfd_ctx *ctx) static void __timerfd_remove_cancel(struct timerfd_ctx *ctx)
{ {
if (ctx->might_cancel) { if (ctx->might_cancel) {

2
include/linux/hrtimer.h
View file

@ -349,8 +349,10 @@ hrtimer_expires_remaining_adjusted(const struct hrtimer *timer)
#ifdef CONFIG_TIMERFD #ifdef CONFIG_TIMERFD
extern void timerfd_clock_was_set(void); extern void timerfd_clock_was_set(void);
extern void timerfd_resume(void);
#else #else
static inline void timerfd_clock_was_set(void) { } static inline void timerfd_clock_was_set(void) { }
static inline void timerfd_resume(void) { }
#endif #endif
extern void hrtimers_resume(void); extern void hrtimers_resume(void);