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| author | Mateusz Guzik <mjg@FreeBSD.org> | 2021-06-02 15:14:58 +0000 |
|---|---|---|
| committer | Mateusz Guzik <mjg@FreeBSD.org> | 2021-06-02 15:14:58 +0000 |
| commit | c9f8dcda856c50325190326a618dc251311bc43a (patch) | |
| tree | d42bac58e46ca45e15eeacb975201bfa3cc03752 | |
| parent | a19ae1b099ad4d43588f15ef19b8506f606b27cb (diff) | |
| download | src-c9f8dcda856c50325190326a618dc251311bc43a.tar.gz src-c9f8dcda856c50325190326a618dc251311bc43a.zip | |
kqueue: replace kq_ncallouts loop with atomic_fetchadd
| -rw-r--r-- | sys/kern/kern_event.c | 12 |
1 files changed, 5 insertions, 7 deletions
diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c index b224ce87087e..63b28cd6024f 100644 --- a/sys/kern/kern_event.c +++ b/sys/kern/kern_event.c @@ -206,7 +206,7 @@ static struct filterops user_filtops = { }; static uma_zone_t knote_zone; -static unsigned int kq_ncallouts = 0; +static unsigned int __exclusive_cache_line kq_ncallouts; static unsigned int kq_calloutmax = 4 * 1024; SYSCTL_UINT(_kern, OID_AUTO, kq_calloutmax, CTLFLAG_RW, &kq_calloutmax, 0, "Maximum number of callouts allocated for kqueue"); @@ -813,18 +813,16 @@ filt_timerattach(struct knote *kn) { struct kq_timer_cb_data *kc; sbintime_t to; - unsigned int ncallouts; int error; error = filt_timervalidate(kn, &to); if (error != 0) return (error); - do { - ncallouts = kq_ncallouts; - if (ncallouts >= kq_calloutmax) - return (ENOMEM); - } while (!atomic_cmpset_int(&kq_ncallouts, ncallouts, ncallouts + 1)); + if (atomic_fetchadd_int(&kq_ncallouts, 1) + 1 > kq_calloutmax) { + atomic_subtract_int(&kq_ncallouts, 1); + return (ENOMEM); + } if ((kn->kn_sfflags & NOTE_ABSTIME) == 0) kn->kn_flags |= EV_CLEAR; /* automatically set */ |