Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932179AbXK2OAd (ORCPT ); Thu, 29 Nov 2007 09:00:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757326AbXK2OAX (ORCPT ); Thu, 29 Nov 2007 09:00:23 -0500 Received: from ms-smtp-01.nyroc.rr.com ([24.24.2.55]:59332 "EHLO ms-smtp-01.nyroc.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755733AbXK2OAW (ORCPT ); Thu, 29 Nov 2007 09:00:22 -0500 Date: Thu, 29 Nov 2007 08:57:01 -0500 (EST) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: Russell King - ARM Linux cc: Remy Bohmer , Daniel Walker , RT , linux-kernel , ARM Linux Mailing List , Thomas Gleixner , Ingo Molnar Subject: Re: [PATCH PREEMPT_RT]: On AT91 ARM: GPIO Interrupt handling can/will stall forever In-Reply-To: <20071129133604.GA23845@flint.arm.linux.org.uk> Message-ID: References: <1196177122.23808.7.camel@imap.mvista.com> <1196178834.23808.11.camel@imap.mvista.com> <3efb10970711280638l3f57104y8cf9f2e58235c3@mail.gmail.com> <20071128172509.GA30173@flint.arm.linux.org.uk> <20071128200550.GA3494@flint.arm.linux.org.uk> <3efb10970711290214v37d85a27k9a84876d9099d7c5@mail.gmail.com> <20071129102506.GB22793@flint.arm.linux.org.uk> <3efb10970711290327s3c60da1ey3b6fae738090ca5@mail.gmail.com> <20071129133604.GA23845@flint.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1390 Lines: 35 On Thu, 29 Nov 2007, Russell King - ARM Linux wrote: > On Thu, Nov 29, 2007 at 12:27:30PM +0100, Remy Bohmer wrote: > > Ah, and looking at the changes to the file, the addition of the mask > and unmask was done by someone who didn't understand what this was > trying to do. So that change should be backed out. > Perhaps only part of the change should be backed out. The part that masks the irq in the handle_simple_irq code. That's from commit 76d2160147f43f982dfe881404cfde9fd0a9da21 which is to not disable an irq line when disable_irq is called. A form of lazy disable irq. This speeds up code that uses disable_irq, since the line is only masked when an interrupt actually arrives. Using disable_irq / enable_irq does no IRQ chip modifications if an interrupt from the IRQ line does not arrive between the two. Now the question is, can something that uses handle_simple_irq call disable_irq? If there is no mask function, I would assume that this would be a noop in such a case. If this is true, then we could remove the mask from handle_simple_irq. But then we might want to add a BUG() in disable_irq for simple_irqs. -- Steve - 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/