kqueue: avoid a possible fork-deadlock

kqueue_fork_copy() is likely to have transitioned at least one knote
through a flux state, so we should check whether we need to wake
anything up on the way out to avoid a possible deadlock.

This was a part of D56210, but we'll close the review with the next
commit.

Fixes:	b11289f87123f ("kqueuex(2): add KQUEUE_CPONFORK")
Reviewed by:	kib, markj

1 files changed, 1 insertions, 1 deletions

diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c
index 2cdc37b710e6..6af53cf6cd91 100644
--- a/sys/kern/kern_event.c
+++ b/sys/kern/kern_event.c
@@ -3147,7 +3147,7 @@ kqueue_fork_copy(struct filedesc *fdp, struct file *fp, struct file *fp1,
 	}
 	kqueue_release(kq, 1);
 	kq1->kq_forksrc = NULL;
-	KQ_UNLOCK(kq);
+	KQ_UNLOCK_FLUX(kq);
 
 	knote_free(marker);
 	return (error);