Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753472Ab2HSOpk (ORCPT ); Sun, 19 Aug 2012 10:45:40 -0400 Received: from mail-wg0-f42.google.com ([74.125.82.42]:58180 "EHLO mail-wg0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751743Ab2HSOph (ORCPT ); Sun, 19 Aug 2012 10:45:37 -0400 Subject: Re: IPv4 BUG: held lock freed! From: Eric Dumazet To: Lin Ming Cc: Fengguang Wu , David Miller , networking , LKML In-Reply-To: References: <20120818021918.GA6499@localhost> <1345380682.5158.201.camel@edumazet-glaptop> Content-Type: text/plain; charset="UTF-8" Date: Sun, 19 Aug 2012 16:45:32 +0200 Message-ID: <1345387532.5158.222.camel@edumazet-glaptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1238 Lines: 39 On Sun, 2012-08-19 at 22:15 +0800, Lin Ming wrote: > Will it still has problem if code goes here without sock_hold(sk)? Not sure of what you mean. At the time tcp_write_timer() runs, we own one reference on the socket. (this reference was taken in sk_reset_timer()) On old kernels, if we found the socket locked by the user, we used to rearm the timer for a 50ms delay (and thus did sock_hold() again) Another way to avoid the bug would to make sure sk_reset_timer() increases refcount _before_ setting the timer, but its adding one atomic in fast path... diff --git a/net/core/sock.c b/net/core/sock.c index 8f67ced..d1745b7 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2114,8 +2114,9 @@ EXPORT_SYMBOL(sk_send_sigurg); void sk_reset_timer(struct sock *sk, struct timer_list* timer, unsigned long expires) { - if (!mod_timer(timer, expires)) - sock_hold(sk); + sock_hold(sk); + if (mod_timer(timer, expires)) + __sock_put(sk); } EXPORT_SYMBOL(sk_reset_timer); -- 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/