Date: Wed, 01 Apr 2026 22:33:31 +0000 From: Kyle Evans <kevans@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: ff1050d2a366 - main - kqueue: simplify knote_fdclose() Message-ID: <69cd9d3b.43e40.112feed2@gitrepo.freebsd.org>
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The branch main has been updated by kevans: URL: https://cgit.FreeBSD.org/src/commit/?id=ff1050d2a366bd288a6ebbf63f98003272513f92 commit ff1050d2a366bd288a6ebbf63f98003272513f92 Author: Kyle Evans <kevans@FreeBSD.org> AuthorDate: 2026-04-01 22:30:48 +0000 Commit: Kyle Evans <kevans@FreeBSD.org> CommitDate: 2026-04-01 22:30:48 +0000 kqueue: simplify knote_fdclose() The influx logic in knote_fdclose() is a little misguided, the resulting wakeup() call should always be redundant: knote_drop_detached() will always issue a wakeup before it returns, so anything waiting on *that* knote that had entered fluxwait should have been woken up then. This is the obvious divergence from the other influx/wakeup pattern in the implementation, which will kn_influx-- and then issue the wakeup after it has processed all of the knotes it can make progress on. While we're here, the kq_knlist cannot shrink, so we can avoid that condition in the loop and avoid potentially excessive wakeups from fluxwait on kqueues that we didn't touch. Reviewed by: kib, markj Differential Revision: https://reviews.freebsd.org/D56210 --- sys/kern/kern_event.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c index 6af53cf6cd91..485123989319 100644 --- a/sys/kern/kern_event.c +++ b/sys/kern/kern_event.c @@ -2836,7 +2836,6 @@ knote_fdclose(struct thread *td, int fd) struct filedesc *fdp = td->td_proc->p_fd; struct kqueue *kq; struct knote *kn; - int influx; FILEDESC_XLOCK_ASSERT(fdp); @@ -2846,22 +2845,25 @@ knote_fdclose(struct thread *td, int fd) */ TAILQ_FOREACH(kq, &fdp->fd_kqlist, kq_list) { KQ_LOCK(kq); + if (kq->kq_knlistsize <= fd || + SLIST_EMPTY(&kq->kq_knlist[fd])) { + KQ_UNLOCK(kq); + continue; + } -again: - influx = 0; - while (kq->kq_knlistsize > fd && - (kn = SLIST_FIRST(&kq->kq_knlist[fd])) != NULL) { + while ((kn = SLIST_FIRST(&kq->kq_knlist[fd])) != NULL) { if (kn_in_flux(kn)) { - /* someone else might be waiting on our knote */ - if (influx) - wakeup(kq); + /* + * Wait for this knote to stabilize, it could be + * the case that it's in the process of being + * dropped anyways. + */ kq->kq_state |= KQ_FLUXWAIT; msleep(kq, &kq->kq_lock, PSOCK, "kqflxwt", 0); - goto again; + continue; } kn_enter_flux(kn); KQ_UNLOCK(kq); - influx = 1; knote_drop(kn, td); KQ_LOCK(kq); }home | help
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