From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarek Poplawski Subject: Re: [patch 2/4] net: use mutex_is_locked() for ASSERT_RTNL() Date: Sun, 16 Dec 2007 19:06:41 +0100 Message-ID: <47656931.1040309@gmail.com> References: <20071214002209.ac748206.akpm@linux-foundation.org> <20071214083037.GA15602@gondor.apana.org.au> <20071214.111514.03773174.davem@davemloft.net> <20071214151136.ae0f969b.akpm@linux-foundation.org> <20071215041827.GC25324@gondor.apana.org.au> <20071214214418.0ecd5e67.akpm@linux-foundation.org> <20071215061021.GA26247@gondor.apana.org.au> <20071215024810.20b8a5ae.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Herbert Xu , David Miller , netdev@vger.kernel.org To: Andrew Morton Return-path: Received: from fg-out-1718.google.com ([72.14.220.158]:55342 "EHLO fg-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752826AbXLPSE5 (ORCPT ); Sun, 16 Dec 2007 13:04:57 -0500 Received: by fg-out-1718.google.com with SMTP id e21so196845fga.17 for ; Sun, 16 Dec 2007 10:04:55 -0800 (PST) In-Reply-To: <20071215024810.20b8a5ae.akpm@linux-foundation.org> Sender: netdev-owner@vger.kernel.org List-ID: Andrew Morton wrote, On 12/15/2007 11:48 AM: > On Sat, 15 Dec 2007 14:10:21 +0800 Herbert Xu wrote: > >> On Fri, Dec 14, 2007 at 09:44:18PM -0800, Andrew Morton wrote: >>> That sounds like a bug in mutex_trylock() to me. >> I was relying on >> >> http://kerneltrap.org/mailarchive/linux-netdev/2007/9/28/325129 >> >> which seems to be a bogus claim now that I actually look at the >> source code. So in that case I'm OK with your patch as long as >> it warns about hard IRQ usage. > > When Eric said > >> Way way deep in mutex debugging on the slowpath there is a unreadable >> and incomprehensible WARN_ON in muxtex_trylock that will trigger if >> you have 10 tons of debugging turned on, and you are in, >> interrupt context, and you manage to hit the slow path. I think that >> is a pretty unlikely scenario. > > I think he's still right. That's if the warning which he managed to find > even still exists. It seemed to exist a few days ago: http://kerneltrap.org/mailarchive/linux-netdev/2007/12/4/473123 Btw., I don't know which of the patches: Eric's or yours will be chosen, but, IMHO, there is no reason to remove rtnl_trylock(), which can be still useful, just like mutex_trylock() is. Regards, Jarek P.