Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760508AbXHFGHO (ORCPT ); Mon, 6 Aug 2007 02:07:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752319AbXHFGG7 (ORCPT ); Mon, 6 Aug 2007 02:06:59 -0400 Received: from mx10.go2.pl ([193.17.41.74]:53359 "EHLO poczta.o2.pl" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753121AbXHFGG5 (ORCPT ); Mon, 6 Aug 2007 02:06:57 -0400 Date: Mon, 6 Aug 2007 08:07:24 +0200 From: Jarek Poplawski To: Ingo Molnar Cc: Gabriel C , Linus Torvalds , Thomas Gleixner , Jean-Baptiste Vignaud , linux-kernel , shemminger , linux-net , netdev , Andrew Morton , Alan Cox , marcin.slusarz@gmail.com Subject: [patch (take 2)] genirq: fix simple and fasteoi irq handlers Message-ID: <20070806060723.GA981@ff.dom.local> References: <4bacf17f0707260016x14fc1c92s628ae64353663833@mail.gmail.com> <20070726081326.GA3197@ff.dom.local> <1185437431.3227.21.camel@chaos> <20070726083120.GA26910@elte.hu> <20070726085523.GA3423@ff.dom.local> <20070726091254.GA8063@elte.hu> <4bacf17f0707300029g5116e70bq4808059dc8b069f1@mail.gmail.com> <20070731155843.GA7033@elte.hu> <46B20E47.6020403@googlemail.com> <20070802201126.GA27000@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070802201126.GA27000@elte.hu> User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4109 Lines: 116 Hi, Sorry, guys! I tried to be so logical that I forgot to unmask my eyes. Regards, Jarek P. ------------> (take 2) Subject: genirq: fix simple and fasteoi irq handlers After the "genirq: do not mask interrupts by default" patch interrupts should be disabled not immediately upon request, but after they happen. But, handle_simple_irq() and handle_fasteoi_irq() can skip this once or more if an irq is just serviced (IRQ_INPROGRESS), possibly disrupting a driver's work. The main reason of problems here, pointing the broken patch and making the first patch which can fix this was done by Marcin Slusarz. Additional test patches of Thomas Gleixner and Ingo Molnar tested by Marcin Slusarz helped to narrow possible reasons even more. Thanks. PS: this patch fixes only one evident error here, but there could be more places affected by above-mentioned change in irq handling. PS 2: After rethinking, IMHO, there are two most probable scenarios here: 1. After hw resend there could be a conflict between retriggered edge type irq and the next level type one: e.g. if this level type irq (io_apic is enabled then) is triggered while retriggered irq is serviced (IRQ_INPROGRESS) there is goto out with eoi, and probably the next such levels are triggered and looping, so probably kind of flood in io_apic until this retriggered edge service has ended. 2. There is something wrong with ioapic_retrigger_irq (less probable because this should be probably seen with 'normal' edge retriggers, but on the other hand, they could be less common). So, if there is #1, this fixed patch should work. But, since level types don't need this retriggers too much I think this "don't mask interrupts by default" idea should be rethinked: is there enough gain to risk such hard to diagnose errors? So, IMHO, there should be at least possibility to turn this off for level types in config (it should be a visible option, so people could find & try this before writing for help or changing a network card). Signed-off-by: Jarek Poplawski --- diff -Nurp 2.6.23-rc1-/kernel/irq/chip.c 2.6.23-rc1/kernel/irq/chip.c --- 2.6.23-rc1-/kernel/irq/chip.c 2007-07-09 01:32:17.000000000 +0200 +++ 2.6.23-rc1/kernel/irq/chip.c 2007-08-05 21:49:46.000000000 +0200 @@ -295,12 +295,11 @@ handle_simple_irq(unsigned int irq, stru spin_lock(&desc->lock); - if (unlikely(desc->status & IRQ_INPROGRESS)) - goto out_unlock; kstat_cpu(cpu).irqs[irq]++; action = desc->action; - if (unlikely(!action || (desc->status & IRQ_DISABLED))) { + if (unlikely(!action || (desc->status & (IRQ_INPROGRESS | + IRQ_DISABLED)))) { if (desc->chip->mask) desc->chip->mask(irq); desc->status &= ~(IRQ_REPLAY | IRQ_WAITING); @@ -318,6 +317,8 @@ handle_simple_irq(unsigned int irq, stru spin_lock(&desc->lock); desc->status &= ~IRQ_INPROGRESS; + if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask) + desc->chip->unmask(irq); out_unlock: spin_unlock(&desc->lock); } @@ -392,18 +393,16 @@ handle_fasteoi_irq(unsigned int irq, str spin_lock(&desc->lock); - if (unlikely(desc->status & IRQ_INPROGRESS)) - goto out; - desc->status &= ~(IRQ_REPLAY | IRQ_WAITING); kstat_cpu(cpu).irqs[irq]++; /* - * If its disabled or no action available + * If it's running, disabled or no action available * then mask it and get out of here: */ action = desc->action; - if (unlikely(!action || (desc->status & IRQ_DISABLED))) { + if (unlikely(!action || (desc->status & (IRQ_INPROGRESS | + IRQ_DISABLED)))) { desc->status |= IRQ_PENDING; if (desc->chip->mask) desc->chip->mask(irq); @@ -420,6 +419,8 @@ handle_fasteoi_irq(unsigned int irq, str spin_lock(&desc->lock); desc->status &= ~IRQ_INPROGRESS; + if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask) + desc->chip->unmask(irq); out: desc->chip->eoi(irq); - 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/