linux-kernel - [PATCH 2/2] call complete_vfork_done() after put_user(clear_child

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Message-ID: <20120531172001.GB17513@redhat.com>
Date:	Thu, 31 May 2012 19:20:01 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Hugh Dickins <hughd@...gle.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Konstantin Khlebnikov <khlebnikov@...nvz.org>,
	Markus Trippelsdorf <markus@...ppelsdorf.de>,
	Martin Mokrejs <mmokrejs@...d.natur.cuni.cz>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] call complete_vfork_done() after
	put_user(clear_child_tid)

From: Konstantin Khlebnikov <khlebnikov@...nvz.org>

Child should wake up parent from vfork() only after finishing all operations with
shared mm. There is no sense to use CLONE_CHILD_CLEARTID together with CLONE_VFORK,
but it looks more accurate now.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@...nvz.org>
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/fork.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 47b4e4f..ba0c0de 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -787,9 +787,6 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm)
 	/* Get rid of any cached register state */
 	deactivate_mm(tsk, mm);
 
-	if (tsk->vfork_done)
-		complete_vfork_done(tsk);
-
 	/*
 	 * If we're exiting normally, clear a user-space tid field if
 	 * requested.  We leave this alone when dying by signal, to leave
@@ -810,6 +807,9 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm)
 		}
 		tsk->clear_child_tid = NULL;
 	}
+
+	if (tsk->vfork_done)
+		complete_vfork_done(tsk);
 }
 
 /*
-- 
1.5.5.1


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