linux-kernel - Re: [PATCH 2/3] drm/scheduler: Don't call wait_event

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Message-ID: <20180425132228.GC7592@redhat.com>
Date:   Wed, 25 Apr 2018 15:22:28 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Andrey Grodzovsky <Andrey.Grodzovsky@....com>,
        Michel Dänzer <michel@...nzer.net>,
        linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, David.Panariti@....com,
        ebiederm@...ssion.com, Alexander.Deucher@....com,
        akpm@...ux-foundation.org, Christian.Koenig@....com
Subject: Re: [PATCH 2/3] drm/scheduler: Don't call wait_event_killable for
 signaled process.

On 04/24, Daniel Vetter wrote:
>
> wait_event_killabel doesn't check for fatal_signal_pending before calling
> schedule, so definitely has a nice race there.

This is fine. See the signal_pending_state() check in __schedule().

And this doesn't differ from wait_event_interruptible(), it too doesn't
check signal_pending(), we rely on schedule() which must not block if the
caller is signalled/killed.

The problem is that it is not clear what should fatal_signal_pending() or
even signal_pending() mean after exit_signals().

Oleg.