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| author | Mark Johnston <markj@FreeBSD.org> | 2022-05-25 00:14:33 +0000 |
|---|---|---|
| committer | Mark Johnston <markj@FreeBSD.org> | 2022-05-25 00:14:33 +0000 |
| commit | 524dadf7a8725dea144571843e611dbdbd59d668 (patch) | |
| tree | 7b1388daab8e501a5e94d6692b631695f2caa352 /sys/kern/kern_event.c | |
| parent | c728c56c870abe230e45cee5c477f0d890ebacef (diff) | |
| download | src-524dadf7a8725dea144571843e611dbdbd59d668.tar.gz src-524dadf7a8725dea144571843e611dbdbd59d668.zip | |
kevent: Fix an off-by-one in filt_timerexpire_l()
Suppose a periodic kevent timer fires close to its deadline, so that
now - kc->next is small. Then delta ends up being 1, and the next timer
deadline is set to (delta + 1) * kc->to, where kc->to is the timer
period. This means that the timer fires at half of the requested rate,
and the value returned in kn_data is similarly inaccurate.
PR: 264131
Fixes: 7cb40543e964 ("filt_timerexpire: do not iterate over the interval")
Reviewed by: kib
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D35313
Diffstat (limited to 'sys/kern/kern_event.c')
| -rw-r--r-- | sys/kern/kern_event.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c index 33607fe8c5f4..f1ee8de4e7ee 100644 --- a/sys/kern/kern_event.c +++ b/sys/kern/kern_event.c @@ -739,7 +739,7 @@ filt_timerexpire_l(struct knote *kn, bool proc_locked) if (delta == 0) delta = 1; kn->kn_data += delta; - kc->next += (delta + 1) * kc->to; + kc->next += delta * kc->to; if (now >= kc->next) /* overflow */ kc->next = now + kc->to; KNOTE_ACTIVATE(kn, 0); /* XXX - handle locking */ |