From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762270AbXG0AN1 (ORCPT ); Thu, 26 Jul 2007 20:13:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755019AbXG0ANU (ORCPT ); Thu, 26 Jul 2007 20:13:20 -0400 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:42589 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752572AbXG0ANT (ORCPT ); Thu, 26 Jul 2007 20:13:19 -0400 Date: Thu, 26 Jul 2007 16:14:41 -0700 (PDT) Message-Id: <20070726.161441.38711978.davem@davemloft.net> To: torvalds@linux-foundation.org Cc: matthew@wil.cx, mingo@elte.hu, linux-kernel@vger.kernel.org Subject: Re: IRQF_DISABLED problem From: David Miller In-Reply-To: References: <20070726201355.GP19275@parisc-linux.org> <20070726.152352.70218024.davem@davemloft.net> X-Mailer: Mew version 5.1.52 on Emacs 21.4 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Linus Torvalds Date: Thu, 26 Jul 2007 16:04:42 -0700 (PDT) > Quite frankly, my preference would be (a) followed by (e) or (f), and > (b)-(d) are in my opinion the worst of the lot with no upsides at all (and > (b) in particular is pretty much _guaranteed_ to break existing setups). I look at some cases, such as EHEA on powerpc which is a pretty modern driver written by not clueless folks, and wonder if they do it because they know the IRQ is non-shared, they know their interrupt handler is insanely simple and short, and just want to avoid the overhead of that sti()/cli() in the caller. All the EHEA interrupt handler does is unconditionally set a state bit and schedule a softirq, then return. The powerpc folks do delayed IRQ enable/disable using software state, but perhaps these drivers were written before that.