From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: lockdep and threaded IRQs (was: ...) Date: Mon, 2 Mar 2009 18:37:08 -0800 Message-ID: <200903021837.08635.david-b@pacbell.net> References: <1235762883-20870-1-git-send-email-me@felipebalbi.com> <200903021633.08736.david-b@pacbell.net> <20090303004427.GA8638@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from n15a.bullet.mail.mud.yahoo.com ([68.142.207.125]:36355 "HELO n15a.bullet.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752501AbZCCChN (ORCPT ); Mon, 2 Mar 2009 21:37:13 -0500 In-Reply-To: <20090303004427.GA8638@elte.hu> Content-Disposition: inline Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Ingo Molnar 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 On Monday 02 March 2009, Ingo Molnar wrote: > >=20 > > p.s. Note that those changes would still leave the > > =A0 =A0 =A0lockdep bug around ... it will still be breaking > > =A0 =A0 =A0various drivers that use normal IRQs, by forcibly > > =A0 =A0 =A0enabling IRQF_DISABLED. >=20 > it's not a bug - and i think Peter explained that already.=20 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 =20 > not really breaking things either - we've had this for more than=20 > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-input" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html