Module Name: src
Committed By: thorpej
Date: Thu Oct 21 00:54:15 UTC 2021
Modified Files:
src/sys/kern: kern_event.c
Log Message:
- Don't use a separate kqueue_timer_lock; just protect those knotes
with the kq->kq_lock.
- Re-factor the guts of knote_activate() into knote_activate_locked(),
and use it in a few places to avoid a few unlock-the-immediately-lock
cycles.
- Define a FILT_TIMER_NOSCHED macro, rather than hard-coding (uintptr_t)-1
in a bunch of difference place.
NFC.
To generate a diff of this commit:
cvs rdiff -u -r1.132 -r1.133 src/sys/kern/kern_event.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/kern_event.c
diff -u src/sys/kern/kern_event.c:1.132 src/sys/kern/kern_event.c:1.133
--- src/sys/kern/kern_event.c:1.132 Wed Oct 13 04:57:19 2021
+++ src/sys/kern/kern_event.c Thu Oct 21 00:54:15 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_event.c,v 1.132 2021/10/13 04:57:19 thorpej Exp $ */
+/* $NetBSD: kern_event.c,v 1.133 2021/10/21 00:54:15 thorpej Exp $ */
/*-
* Copyright (c) 2008, 2009, 2021 The NetBSD Foundation, Inc.
@@ -63,7 +63,7 @@
#endif /* _KERNEL_OPT */
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_event.c,v 1.132 2021/10/13 04:57:19 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_event.c,v 1.133 2021/10/21 00:54:15 thorpej Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -101,6 +101,7 @@ static void kqueue_doclose(struct kqueue
static void knote_detach(struct knote *, filedesc_t *fdp, bool);
static void knote_enqueue(struct knote *);
static void knote_activate(struct knote *);
+static void knote_activate_locked(struct knote *);
static void filt_kqdetach(struct knote *);
static int filt_kqueue(struct knote *, long hint);
@@ -273,7 +274,6 @@ static size_t user_kfiltersz; /* size
* KM_SLEEP is not).
*/
static krwlock_t kqueue_filter_lock; /* lock on filter lists */
-static kmutex_t kqueue_timer_lock; /* for EVFILT_TIMER */
#define KQ_FLUX_WAIT(kq) (void)cv_wait(&kq->kq_cv, &kq->kq_lock)
#define KQ_FLUX_WAKEUP(kq) cv_broadcast(&kq->kq_cv)
@@ -514,7 +514,6 @@ kqueue_init(void)
{
rw_init(&kqueue_filter_lock);
- mutex_init(&kqueue_timer_lock, MUTEX_DEFAULT, IPL_SOFTCLOCK);
kqueue_listener = kauth_listen_scope(KAUTH_SCOPE_PROCESS,
kqueue_listener_cb, NULL);
@@ -877,10 +876,10 @@ knote_proc_exec(struct proc *p)
kq = kn->kn_kq;
mutex_spin_enter(&kq->kq_lock);
fflags = (kn->kn_fflags |= (kn->kn_sfflags & NOTE_EXEC));
- mutex_spin_exit(&kq->kq_lock);
if (fflags) {
- knote_activate(kn);
+ knote_activate_locked(kn);
}
+ mutex_spin_exit(&kq->kq_lock);
}
mutex_exit(p->p_lock);
@@ -1095,10 +1094,10 @@ knote_proc_fork(struct proc *p1, struct
KASSERT(mutex_owned(&kq->kq_lock));
}
fflags = kn->kn_fflags;
- mutex_spin_exit(&kq->kq_lock);
if (fflags) {
- knote_activate(kn);
+ knote_activate_locked(kn);
}
+ mutex_spin_exit(&kq->kq_lock);
}
mutex_exit(p1->p_lock);
@@ -1141,31 +1140,34 @@ knote_proc_exit(struct proc *p)
kn->kn_status |= KN_DETACHED;
SLIST_REMOVE_HEAD(&p->p_klist, kn_selnext);
}
- mutex_spin_exit(&kq->kq_lock);
/*
* Always activate the knote for NOTE_EXIT regardless
* of whether or not the listener cares about it.
* This matches historical behavior.
*/
- knote_activate(kn);
+ knote_activate_locked(kn);
+ mutex_spin_exit(&kq->kq_lock);
}
}
+#define FILT_TIMER_NOSCHED ((uintptr_t)-1)
+
static void
filt_timerexpire(void *knx)
{
struct knote *kn = knx;
+ struct kqueue *kq = kn->kn_kq;
- mutex_enter(&kqueue_timer_lock);
+ mutex_spin_enter(&kq->kq_lock);
kn->kn_data++;
- knote_activate(kn);
- if (kn->kn_sdata != (uintptr_t)-1) {
+ knote_activate_locked(kn);
+ if (kn->kn_sdata != FILT_TIMER_NOSCHED) {
KASSERT(kn->kn_sdata > 0 && kn->kn_sdata <= INT_MAX);
callout_schedule((callout_t *)kn->kn_hook,
(int)kn->kn_sdata);
}
- mutex_exit(&kqueue_timer_lock);
+ mutex_spin_exit(&kq->kq_lock);
}
static int
@@ -1245,9 +1247,9 @@ filt_timerattach(struct knote *kn)
if ((kn->kn_flags & EV_ONESHOT) != 0 ||
(kn->kn_sfflags & NOTE_ABSTIME) != 0) {
/* Timer does not repeat. */
- kn->kn_sdata = (uintptr_t)-1;
+ kn->kn_sdata = FILT_TIMER_NOSCHED;
} else {
- KASSERT((uintptr_t)tticks != (uintptr_t)-1);
+ KASSERT((uintptr_t)tticks != FILT_TIMER_NOSCHED);
kn->kn_sdata = tticks;
}
@@ -1275,17 +1277,9 @@ filt_timerdetach(struct knote *kn)
callout_t *calloutp;
struct kqueue *kq = kn->kn_kq;
- /*
- * We don't need to hold the kqueue_timer_lock here; even
- * if filt_timerexpire() misses our setting of EV_ONESHOT,
- * we are guaranteed that the callout will no longer be
- * scheduled even if we attempted to halt it after it already
- * started running, even if it rescheduled itself.
- */
-
- mutex_spin_enter(&kq->kq_lock);
/* prevent rescheduling when we expire */
- kn->kn_flags |= EV_ONESHOT;
+ mutex_spin_enter(&kq->kq_lock);
+ kn->kn_sdata = FILT_TIMER_NOSCHED;
mutex_spin_exit(&kq->kq_lock);
calloutp = (callout_t *)kn->kn_hook;
@@ -1304,11 +1298,12 @@ filt_timerdetach(struct knote *kn)
static int
filt_timer(struct knote *kn, long hint)
{
+ struct kqueue *kq = kn->kn_kq;
int rv;
- mutex_enter(&kqueue_timer_lock);
+ mutex_spin_enter(&kq->kq_lock);
rv = (kn->kn_data != 0);
- mutex_exit(&kqueue_timer_lock);
+ mutex_spin_exit(&kq->kq_lock);
return rv;
}
@@ -2613,7 +2608,7 @@ knote_enqueue(struct knote *kn)
* Queue new event for knote.
*/
static void
-knote_activate(struct knote *kn)
+knote_activate_locked(struct knote *kn)
{
struct kqueue *kq;
@@ -2621,10 +2616,9 @@ knote_activate(struct knote *kn)
kq = kn->kn_kq;
- mutex_spin_enter(&kq->kq_lock);
if (__predict_false(kn->kn_status & KN_WILLDETACH)) {
/* Don't bother enqueueing a dying knote. */
- goto out;
+ return;
}
kn->kn_status |= KN_ACTIVE;
if ((kn->kn_status & (KN_QUEUED | KN_DISABLED)) == 0) {
@@ -2637,7 +2631,15 @@ knote_activate(struct knote *kn)
cv_broadcast(&kq->kq_cv);
selnotify(&kq->kq_sel, 0, NOTE_SUBMIT);
}
- out:
+}
+
+static void
+knote_activate(struct knote *kn)
+{
+ struct kqueue *kq = kn->kn_kq;
+
+ mutex_spin_enter(&kq->kq_lock);
+ knote_activate_locked(kn);
mutex_spin_exit(&kq->kq_lock);
}
