From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755306AbZCCCh2 (ORCPT ); Mon, 2 Mar 2009 21:37:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752733AbZCCChO (ORCPT ); Mon, 2 Mar 2009 21:37:14 -0500 Received: from n30.bullet.mail.mud.yahoo.com ([68.142.207.49]:22583 "HELO n30.bullet.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752399AbZCCChN (ORCPT ); Mon, 2 Mar 2009 21:37:13 -0500 X-Yahoo-Newman-Id: 751641.89587.bm@omp416.mail.mud.yahoo.com DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=pacbell.net; h=Received:X-YMail-OSG:X-Yahoo-Newman-Property:From:To:Subject:Date:User-Agent:Cc:References:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding:Content-Disposition:Message-Id; b=mwY8iI0yx3Z/l5vhf8M8YNWnCs+5YZA96AbIu5o+iHmkBOz6dWo8ZXhrBxjQ21TB558svMJCGQLgnZAgEFWQnN6tBUMSyuhZkzS51h3M2FXRZLUkXu23toKL+cDr6wXtDABioA2EDjhp1j5V1iaLXE84Oq3ZmUWLWtMi12XJ7R4= ; X-YMail-OSG: bb8q6G8VM1kqQ4DaoOv7NM_uvwExs3XCgND.nu.UG3RIKrGirG2Of2vohIb4Zf61N247VCrXtJiQocYxHZ7yeCx2qAhNQu2RMC7nBZCUKyJjTI4afbBTx4DmzL56IouOSwutpo0TNF3NqmavIdoGvFRJFsmiOG6ijefKZ0uo6VSN3IauLIrKyb3ZhtDh X-Yahoo-Newman-Property: ymail-3 From: David Brownell To: Ingo Molnar Subject: Re: lockdep and threaded IRQs (was: ...) Date: Mon, 2 Mar 2009 18:37:08 -0800 User-Agent: KMail/1.9.10 Cc: Peter Zijlstra , Andrew Morton , me@felipebalbi.com, linux-kernel@vger.kernel.org, linux-input@vger.kernel.org, felipe.balbi@nokia.com, dmitry.torokhov@gmail.com, sameo@openedhand.com, tglx@linutronix.de References: <1235762883-20870-1-git-send-email-me@felipebalbi.com> <200903021633.08736.david-b@pacbell.net> <20090303004427.GA8638@elte.hu> In-Reply-To: <20090303004427.GA8638@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8bit Content-Disposition: inline Message-Id: <200903021837.08635.david-b@pacbell.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday 02 March 2009, Ingo Molnar wrote: > > > > p.s. Note that those changes would still leave the > >      lockdep bug around ... it will still be breaking > >      various drivers that use normal IRQs, by forcibly > >      enabling IRQF_DISABLED. > > it's not a bug - and i think Peter explained that already. No. But I did get a non-response that didn't include any explanation, and relied totally on unfounded assertions combined with the presumption that someday IRQF_DISABLED will be forced on in all drivers. > It's > not really breaking things either - we've had this for more than > 2 years. I happened across two MMC host adapter drivers which it broke. They preceded the patch whereby lockdep changes request_irq() semantics. The drivers break only with lockdep ... so platforms relying on those can't use lockdep. No reason to think there aren't more such bugs lurking. We also wasted quite a few months tracking down USB bugs that were masked by that patch ... the indeterminacy of IRQF_DISABLED behavior given IRQF_SHARED was hidden by enabling lockdep. Led to a lot of totally crapulous oops traces, I assure you. So ... it has most certainly broken things. There has seemed to be a bit of stick-fingers-in-ears going on, that prevents hearing about such problems though. - Dave