linux-kernel - [PATCH 1/3] signals: Allow generation of SIGKILL to exiting task.

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Date:   Tue, 24 Apr 2018 11:30:34 -0400
From:   Andrey Grodzovsky <andrey.grodzovsky@....com>
To:     <linux-kernel@...r.kernel.org>, <amd-gfx@...ts.freedesktop.org>
CC:     <Alexander.Deucher@....com>, <Christian.Koenig@....com>,
        <David.Panariti@....com>, <oleg@...hat.com>,
        <akpm@...ux-foundation.org>, <ebiederm@...ssion.com>,
        Andrey Grodzovsky <andrey.grodzovsky@....com>
Subject: [PATCH 1/3] signals: Allow generation of SIGKILL to exiting task.

Currently calling wait_event_killable as part of exiting process
will stall forever since SIGKILL generation is suppresed by PF_EXITING.

In our partilaur case AMDGPU driver wants to flush all GPU jobs in
flight before shutting down. But if some job hangs the pipe we still want to
be able to kill it and avoid a process in D state.

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@....com>
---
 kernel/signal.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index c6e4c83..c49c706 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -886,10 +886,10 @@ static inline int wants_signal(int sig, struct task_struct *p)
 {
 	if (sigismember(&p->blocked, sig))
 		return 0;
-	if (p->flags & PF_EXITING)
-		return 0;
 	if (sig == SIGKILL)
 		return 1;
+	if (p->flags & PF_EXITING)
+		return 0;
 	if (task_is_stopped_or_traced(p))
 		return 0;
 	return task_curr(p) || !signal_pending(p);
-- 
2.7.4