[PATCH v2 21/37] hrtimer: Make remote enqueue decision less restrictive

Anna-Maria Gleixner
2017-10-22T21:47:16Z

[-- Attachment #1: hrtimer--check-target-fix.patch --]
[-- Type: text/plain, Size: 938 bytes --]

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>
---
kernel/time/hrtimer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -168,7 +168,7 @@ hrtimer_check_target(struct hrtimer *tim
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;
}

#ifdef CONFIG_NO_HZ_COMMON