Date: Wed, 01 Apr 2026 22:33:28 +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: 0b4f0e0515d0 - main - kqueue: compare against the size in kqueue_expand Message-ID: <69cd9d38.452a7.4d5842ab@gitrepo.freebsd.org>
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The branch main has been updated by kevans: URL: https://cgit.FreeBSD.org/src/commit/?id=0b4f0e0515d0c7ec855cd654ae5dc562f4931cae commit 0b4f0e0515d0c7ec855cd654ae5dc562f4931cae 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: compare against the size in kqueue_expand This is a cosmetic change, rather than a functional one: comparing the knlistsize against the fd requires a little bit of mental gymnastics to confirm that this is fine and not doing unnecessary work in some cases. Notably, one must consider that kq_knlistsize only grows in KQEXTENT chunks, which means that concurrent threads trying to grow the kqueue to consecutive fds will usually not result in the list being replaced twice. One can also more clearly rule out classes of arithmetic problems in the final `else` branch. Reviewed by: kib, markj Differential Revision: https://reviews.freebsd.org/D56209 --- sys/kern/kern_event.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c index f984161bfcd6..2cdc37b710e6 100644 --- a/sys/kern/kern_event.c +++ b/sys/kern/kern_event.c @@ -2013,10 +2013,11 @@ kqueue_expand(struct kqueue *kq, const struct filterops *fops, uintptr_t ident, to_free = NULL; if (fops->f_isfd) { fd = ident; - if (kq->kq_knlistsize <= fd) { - size = kq->kq_knlistsize; - while (size <= fd) + size = atomic_load_int(&kq->kq_knlistsize); + if (size <= fd) { + do { size += KQEXTENT; + } while (size <= fd); list = malloc(size * sizeof(*list), M_KQUEUE, mflag); if (list == NULL) return ENOMEM; @@ -2024,7 +2025,7 @@ kqueue_expand(struct kqueue *kq, const struct filterops *fops, uintptr_t ident, if ((kq->kq_state & KQ_CLOSING) != 0) { to_free = list; error = EBADF; - } else if (kq->kq_knlistsize > fd) { + } else if (kq->kq_knlistsize >= size) { to_free = list; } else { if (kq->kq_knlist != NULL) { @@ -2039,6 +2040,7 @@ kqueue_expand(struct kqueue *kq, const struct filterops *fops, uintptr_t ident, kq->kq_knlistsize = size; kq->kq_knlist = list; } + MPASS(error != 0 || kq->kq_knlistsize > fd); KQ_UNLOCK(kq); } } else {home | help
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