Date: Mon, 06 Sep 2021 11:20:31 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 258310] kevent() does not see signal with zero timeout Message-ID: <bug-258310-227-dJ6byTqe7r@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-258310-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258310 Konstantin Belousov <kib@FreeBSD.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |kib@FreeBSD.org --- Comment #1 from Konstantin Belousov <kib@FreeBSD.org> --- So the problem is actually not that kevent does not get signal notification. It is that kqueue attached to kqueue with the signal event suddenly reports no events when you specify zero timeout, i.e. non-blocking peek. Am I right? This is because kqueue subsystem has to fight with the recursion and deadlock. If kqueue has another kqueue attached to it, then notification of the attached kqueue is delegated to a task. See knote_enqueue()->kqueue_wakeup()-> kqueue_schedtask(). Until task run, kq->kq_count == 0 and this together with timespec being 0 (AKA unset) causes kqueue_scan() to immediately return 0. I am not sure if this is worth complications to make the wakeup synchronous. -- You are receiving this mail because: You are the assignee for the bug.help
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