Commit 2ac2dccc authored Dec 21, 2017 by Anna-Maria Gleixner Committed by Ingo Molnar Jan 16, 2018

hrtimer: Make remote enqueue decision less restrictive



The current decision whether a timer can be queued on a remote CPU checks
for timer->expiry <= remote_cpu_base.expires_next.

This is too restrictive because a timer with the same expiry time as an
existing timer will be enqueued on right-hand size of the existing timer
inside the rbtree, i.e. behind the first expiring timer.

So its safe to allow enqueuing timers with the same expiry time as the
first expiring timer on a remote CPU base.

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/20171221104205.7269-22-anna-maria@linutronix.de


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 14c80341

kernel/time/hrtimer.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -168,7 +168,7 @@ hrtimer_check_target(struct hrtimer timer, struct hrtimer_clock_base new_base)
		ktime_t expires;

		expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
		return expires <= new_base->cpu_base->expires_next;
		return expires < new_base->cpu_base->expires_next;
		}

		static inline