linux-kernel - [PATCH][RFC] Always unlock 'tasklist_lock' in kernel/exit.c::do

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Message-ID: <alpine.LNX.2.00.1012202324540.23785@swampdragon.chaosbits.net>
Date:	Mon, 20 Dec 2010 23:30:38 +0100 (CET)
From:	Jesper Juhl <jj@...osbits.net>
To:	linux-kernel@...r.kernel.org
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Roland McGrath <roland@...hat.com>,
	Ingo Molnar <mingo@...e.hu>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH][RFC] Always unlock 'tasklist_lock' in
 kernel/exit.c::do_wait()

Hi,

The Coverity checker spotted this. I think it has a point, but I'm not 
intimate with this code so there could be somethingI'm missing.

It seems that kernel/exit.c::do_wait() does not always release 
'tasklist_lock'. There are multiple ways the code could be changed to make 
sure it's always released, I just picked the most straight forward one.

Does this look right to everyone else or is it just me?
I've only compile tested the patch so far.


Signed-off-by: Jesper Juhl <jj@...osbits.net>
---
 exit.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/exit.c b/kernel/exit.c
index 676149a..456b13d 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1647,12 +1647,16 @@ repeat:
 	tsk = current;
 	do {
 		retval = do_wait_thread(wo, tsk);
-		if (retval)
+		if (retval) {
+			read_unlock(&tasklist_lock);
 			goto end;
+		}
 
 		retval = ptrace_do_wait(wo, tsk);
-		if (retval)
+		if (retval) {
+			read_unlock(&tasklist_lock);
 			goto end;
+		}
 
 		if (wo->wo_flags & __WNOTHREAD)
 			break;



-- 
Jesper Juhl <jj@...osbits.net>            http://www.chaosbits.net/
Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
Plain text mails only, please.

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