Return-path: Received: from palinux.external.hp.com ([192.25.206.14]:43319 "EHLO mail.parisc-linux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756014AbYE0LYU (ORCPT ); Tue, 27 May 2008 07:24:20 -0400 Date: Tue, 27 May 2008 05:24:03 -0600 From: Matthew Wilcox To: Daniel Walker Cc: Rusty Russell , Michal Schmidt , linville@tuxdriver.com, mingo@elte.hu, linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, arjan@infradead.org Subject: Re: [PATCH] net: wireless: airo semaphore to mutex Message-ID: <20080527112403.GI30894@parisc-linux.org> (sfid-20080527_132424_117790_B981F57A) References: <20080522232103.120033152@mvista.com> <20080526192914.31045d09@brian.englab.brq.redhat.com> <200805271117.23051.rusty@rustcorp.com.au> <20080527021503.GH30894@parisc-linux.org> <1211862881.18130.243.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1211862881.18130.243.camel@localhost.localdomain> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Mon, May 26, 2008 at 09:34:41PM -0700, Daniel Walker wrote: > > On Mon, 2008-05-26 at 20:15 -0600, Matthew Wilcox wrote: > > On Tue, May 27, 2008 at 11:17:22AM +1000, Rusty Russell wrote: > > > On Tuesday 27 May 2008 03:29:14 Michal Schmidt wrote: > > > > Mutexes are not allowed in interrupt context, not even mutex_trylock. > > > > > > As an aside, does anyone know why? I know the documentation says so, but it > > > wasn't immediately obvious to me. I asked before to no response... > > > > Because mutexes have an owner. In interrupt context, there is no owner. > > This owner is used to do priority boosts as well as debugging. > > I don't think regular mutexes do boosting, the rtmutex does tho .. I > think it's more a issue with lockdep complaining about the context, but > that exists to just plain disallow this type of usage on principal . You're right, I got confused, it's only rtmutexes that do priority inheritance. I suppose we could have a special 'interrupt context' owner for the purposes of LOCKDEP. Ingo? -- Intel are signing my paycheques ... these opinions are still mine "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step."