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Subject[GIT PULL] timer fix
Linus,

Please pull the latest timers-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers-urgent-for-linus

# HEAD: e430d802d6a3aaf61bd3ed03d9404888a29b9bf9 timer: Read jiffies once when forwarding base clk

Fixes a timer expiry bug that would cause spurious delay of timers.

Thanks,

Ingo

------------------>
Li RongQing (1):
timer: Read jiffies once when forwarding base clk


kernel/time/timer.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 0e315a2e77ae..4820823515e9 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1678,24 +1678,26 @@ void timer_clear_idle(void)
static int collect_expired_timers(struct timer_base *base,
struct hlist_head *heads)
{
+ unsigned long now = READ_ONCE(jiffies);
+
/*
* NOHZ optimization. After a long idle sleep we need to forward the
* base to current jiffies. Avoid a loop by searching the bitfield for
* the next expiring timer.
*/
- if ((long)(jiffies - base->clk) > 2) {
+ if ((long)(now - base->clk) > 2) {
unsigned long next = __next_timer_interrupt(base);

/*
* If the next timer is ahead of time forward to current
* jiffies, otherwise forward to the next expiry time:
*/
- if (time_after(next, jiffies)) {
+ if (time_after(next, now)) {
/*
* The call site will increment base->clk and then
* terminate the expiry loop immediately.
*/
- base->clk = jiffies;
+ base->clk = now;
return 0;
}
base->clk = next;
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