Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756618AbYF3F3h (ORCPT ); Mon, 30 Jun 2008 01:29:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752085AbYF3F3Z (ORCPT ); Mon, 30 Jun 2008 01:29:25 -0400 Received: from smtp.nokia.com ([192.100.122.230]:18368 "EHLO mgw-mx03.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751882AbYF3F3Z (ORCPT ); Mon, 30 Jun 2008 01:29:25 -0400 Message-ID: <48686D8F.8010901@nokia.com> Date: Mon, 30 Jun 2008 08:22:23 +0300 From: Stefan Becker User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: ext David Brownell , linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org CC: ext Alan Stern Subject: Re: PATCH: 2.6.26-rc8: Fix IRQF_DISABLED for shared interrupts References: <200806281251.21299.david-b@pacbell.net> <4867A2DE.3070509@nokia.com> <200806292009.26975.david-b@pacbell.net> In-Reply-To: <200806292009.26975.david-b@pacbell.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 30 Jun 2008 05:22:23.0861 (UTC) FILETIME=[47127250:01C8DA71] X-Nokia-AV: Clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1607 Lines: 52 Hi David, ext David Brownell wrote: > > By the way, did you notice the oddness of IRQF_SAMPLE_RANDOM there? > For a shared IRQ, I would rather think that if any IRQ was flagged > as "too predictable for use as IRQ randomness" (by not having that > flag set) then the IRQ should never be sampled ... there's some odd > thought (or non-thought) involved in IRQ sharing. Good question. What happens when you mix a random and a not-so-random source: does the result have an as good random quality as the original random source? If the answer is yes then the current code is OK. > One technical comment: > >> --- a/kernel/irq/internals.h >> >> + * IRQF_DISABLED_CUMULATIVE - one handler in the chain has IRQF_DISABLED >> set + */ >> +#define IRQF_DISABLED_CUMULATIVE 0x80000000 > > I don't think you should need that flag; and if you did, it should be > declared in to prevent anyone else from using that bit > for some other purpose. My fear was that if it is a public flag in linux/interrupt.h then somebody might misuse it. > Instead, I think you can set IRQF_DISABLED in irq_desc[irq].status > to achieve the same effect. I actually had the same idea but missed the "irq" in the handle_IRQ_event() signature :-( I'll try to send an updated patch today... Regards, Stefan --- Stefan Becker E-Mail: Stefan.Becker@nokia.com -- 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/