diff options
| author | Visa Hankala <visa@cvs.openbsd.org> | 2020-02-14 16:50:26 +0000 |
|---|---|---|
| committer | Visa Hankala <visa@cvs.openbsd.org> | 2020-02-14 16:50:26 +0000 |
| commit | 77a96ecbc64631373454c6ec90ebce1103d9f1a4 (patch) | |
| tree | c210f39857b62b82b635c398e43a422ab4b6fdf8 /sys/kern | |
| parent | 6bae8e63db16d9b994934de3ab96cf15bb5aab74 (diff) | |
Defer chained activation of kqueues. This makes easier to introduce new
locks. The deferring also prevents kernel stack exhaustion with deep
kqueue hierarchies.
OK anton@, mpi@
Diffstat (limited to 'sys/kern')
| -rw-r--r-- | sys/kern/kern_event.c | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c index 8c42b479251..e2ae0fb95d8 100644 --- a/sys/kern/kern_event.c +++ b/sys/kern/kern_event.c @@ -1,4 +1,4 @@ -/* $OpenBSD: kern_event.c,v 1.123 2020/02/09 14:09:08 visa Exp $ */ +/* $OpenBSD: kern_event.c,v 1.124 2020/02/14 16:50:25 visa Exp $ */ /*- * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org> @@ -72,6 +72,7 @@ void kqueue_wakeup(struct kqueue *kq); static void kqueue_expand_hash(struct kqueue *kq); static void kqueue_expand_list(struct kqueue *kq, int fd); +static void kqueue_task(void *); const struct fileops kqueueops = { .fo_read = kqueue_read, @@ -498,6 +499,7 @@ sys_kqueue(struct proc *p, void *v, register_t *retval) kq->kq_refs = 1; kq->kq_fdp = fdp; TAILQ_INIT(&kq->kq_head); + task_set(&kq->kq_task, kqueue_task, kq); fdplock(fdp); error = falloc(p, &fp, &fd); @@ -1061,6 +1063,10 @@ kqueue_close(struct file *fp, struct proc *p) kq->kq_state |= KQ_DYING; kqueue_wakeup(kq); + + KASSERT(SLIST_EMPTY(&kq->kq_sel.si_note)); + task_del(systq, &kq->kq_task); + KQRELE(kq); KERNEL_UNLOCK(); @@ -1068,6 +1074,15 @@ kqueue_close(struct file *fp, struct proc *p) return (0); } +static void +kqueue_task(void *arg) +{ + struct kqueue *kq = arg; + + KNOTE(&kq->kq_sel.si_note, 0); + KQRELE(kq); +} + void kqueue_wakeup(struct kqueue *kq) { @@ -1079,8 +1094,12 @@ kqueue_wakeup(struct kqueue *kq) if (kq->kq_state & KQ_SEL) { kq->kq_state &= ~KQ_SEL; selwakeup(&kq->kq_sel); - } else - KNOTE(&kq->kq_sel.si_note, 0); + } else if (!SLIST_EMPTY(&kq->kq_sel.si_note)) { + /* Defer activation to avoid recursion. */ + KQREF(kq); + if (!task_add(systq, &kq->kq_task)) + KQRELE(kq); + } } static void |