Return-Path: <linux-kernel-owner+willy=40w.ods.org@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id <S317927AbSGKWbW>; Thu, 11 Jul 2002 18:31:22 -0400
Received: (majordomo@vger.kernel.org) by vger.kernel.org
	id <S317928AbSGKWbV>; Thu, 11 Jul 2002 18:31:21 -0400
Received: from ns.suse.de ([213.95.15.193]:45576 "EHLO Cantor.suse.de")
	by vger.kernel.org with ESMTP id <S317927AbSGKWbS>;
	Thu, 11 Jul 2002 18:31:18 -0400
To: Dawson Engler <engler@csl.Stanford.EDU>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [CHECKER] 56 potential lock/unlock bugs in 2.5.8
References: <200207112135.OAA03801@csl.Stanford.EDU.suse.lists.linux.kernel>
From: Andi Kleen <ak@suse.de>
Date: 12 Jul 2002 00:34:04 +0200
In-Reply-To: Dawson Engler's message of "11 Jul 2002 23:39:35 +0200"
Message-ID: <p73r8i9vqqr.fsf@oldwotan.suse.de>
X-Mailer: Gnus v5.7/Emacs 20.6
Sender: linux-kernel-owner@vger.kernel.org
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1342
Lines: 29

Dawson Engler <engler@csl.Stanford.EDU> writes:

> [BUG]  recheck: seems unlikely, though it does seem that the path is valid.
> /u2/engler/mc/oses/linux/2.5.8/net/ipv6/tcp_ipv6.c:206:tcp_v6_get_port: ERROR:A_B:112:206:Did not reverse 'spin_lock' [COUNTER=spin_lock:112] [fit=3] [fit_fn=11] [fn_ex=2] [fn_counter=1] [ex=5619] [counter=272] [z = 1.34804760770983] [fn-z = -2.25170500701057]
> 		rover = tcp_port_rover;
> 		do {	rover++;
> 			if ((rover < low) || (rover > high))
> 				rover = low;
> 			head = &tcp_bhash[tcp_bhashfn(rover)];
> Start --->
> 			spin_lock(&head->lock);
> 

           } while (--remaining > 0);
                tcp_port_rover = rover;
                spin_unlock(&tcp_portalloc_lock);

                /* Exhausted local port range during search? */
                ret = 1;
                if (remaining <= 0)
                        goto fail;


the goto can only hit when the lock hasn't been taken, so not unlocking it
is correct. It just rechecks the loop end condition, but your tool probably
doesn't know that. The wonders of structured programming :-)


-Andi
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/