From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754912Ab0CYU6W (ORCPT ); Thu, 25 Mar 2010 16:58:22 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:51730 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754890Ab0CYU6U (ORCPT ); Thu, 25 Mar 2010 16:58:20 -0400 Date: Thu, 25 Mar 2010 13:53:25 -0700 (PDT) From: Linus Torvalds To: Ingo Molnar cc: Peter Zijlstra , Thomas Gleixner , Andi Kleen , x86@kernel.org, LKML , jesse.brandeburg@intel.com Subject: Re: [PATCH] Prevent nested interrupts when the IRQ stack is near overflowing v2 In-Reply-To: Message-ID: References: <20100324190150.GA18803@basil.fritz.box> <20100325003652.GG20695@one.firstfloor.org> <20100325093744.GH20695@one.firstfloor.org> <1269539254.12097.100.camel@laptop> <20100325182930.GA7709@elte.hu> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 25 Mar 2010, Linus Torvalds wrote: > > And I just checked: even the 8250 serial driver doesn't use IRQF_DISABLED > any more, so doing that shouldn't cause any latency issues (sure, the > serial driver may interrupt another irq, but another irq can also > interrupt the serial driver as things stand now, so the original latency > issue with fast irq handlers doesn't actually work these days _anyway_). Btw, if we really do decide that everybody is IRQF_DISABLED, that really should make the whole mask-and-ack issue for the irq controllers go away. We'd still need it, but only for the very special IDE controller case and others who _explicitly_ re-enable interrupts. Those would really have to cause the irq to be masked so that we don't get issues with recursive irqs of the same kind. Linus