From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932216AbVLVLnA (ORCPT ); Thu, 22 Dec 2005 06:43:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932279AbVLVLnA (ORCPT ); Thu, 22 Dec 2005 06:43:00 -0500 Received: from canuck.infradead.org ([205.233.218.70]:27810 "EHLO canuck.infradead.org") by vger.kernel.org with ESMTP id S932216AbVLVLm6 (ORCPT ); Thu, 22 Dec 2005 06:42:58 -0500 Subject: [PATCH] Debug shared irqs. From: David Woodhouse To: akpm@osdl.org Cc: arjan@infradead.org, linux-kernel@vger.kernel.org Content-Type: text/plain Date: Thu, 22 Dec 2005 11:42:46 +0000 Message-Id: <1135251766.3557.13.camel@pmac.infradead.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit X-Spam-Score: 0.0 (/) X-SRS-Rewrite: SMTP reverse-path rewritten from by canuck.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Drivers registering IRQ handlers with SA_SHIRQ really ought to be able to handle an interrupt happening before request_irq() returns. They also ought to be able to handle an interrupt happening during the start of their call to free_irq(). Let's test that hypothesis.... Signed-off-by: David Woodhouse I'm not wonderfully happy with the faked pt_regs, but I think it ought to be OK like that. --- linux-2.6.14/lib//Kconfig.debug~ 2005-12-19 00:57:18.000000000 +0000 +++ linux-2.6.14/lib//Kconfig.debug 2005-12-22 11:37:27.000000000 +0000 @@ -176,6 +176,15 @@ config DEBUG_VM If unsure, say N. +config SHARE_ME_HARDER + bool "Debug shared IRQ handlers" + depends on GENERIC_HARDIRQS + help + Enable this to generate a spurious interrupt as soon as a shared interrupt + handler is registered, and just before one is deregistered. Drivers ought + to be able to handle interrupts coming in at those some; some don't and + need to be caught. + config FRAME_POINTER bool "Compile the kernel with frame pointers" depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML) --- linux-2.6.14/kernel/irq/manage.c~ 2005-12-19 00:57:18.000000000 +0000 +++ linux-2.6.14/kernel/irq/manage.c 2005-12-22 11:24:40.000000000 +0000 @@ -238,6 +238,10 @@ int setup_irq(unsigned int irq, struct i return 0; } +#ifdef CONFIG_SHARE_ME_HARDER +static struct pt_regs shirq_fakeregs; +#endif + /** * free_irq - free an interrupt * @irq: Interrupt line to free @@ -257,6 +261,7 @@ void free_irq(unsigned int irq, void *de struct irq_desc *desc; struct irqaction **p; unsigned long flags; + irqreturn_t (*handler)(int, void *, struct pt_regs *) = NULL; if (irq >= NR_IRQS) return; @@ -295,6 +300,8 @@ void free_irq(unsigned int irq, void *de /* Make sure it's not being used on another CPU */ synchronize_irq(irq); + if (action->flags & SA_SHIRQ) + handler = action->handler; kfree(action); return; } @@ -302,6 +309,15 @@ void free_irq(unsigned int irq, void *de spin_unlock_irqrestore(&desc->lock,flags); return; } +#ifdef CONFIG_SHARE_ME_HARDER + if (handler) { + /* It's a shared IRQ -- the driver ought to be prepared for it to happen + even now it's being freed, so let's make sure.... + We do this after actually deregistering it, to make sure that a 'real' + IRQ doesn't run in parallel with our fake. */ + handler(irq, dev_id, &shirq_fakeregs); + } +#endif } EXPORT_SYMBOL(free_irq); @@ -366,6 +382,16 @@ int request_irq(unsigned int irq, action->next = NULL; action->dev_id = dev_id; +#ifdef CONFIG_SHARE_ME_HARDER + if (irqflags & SA_SHIRQ) { + /* It's a shared IRQ -- the driver ought to be prepared for it to happen + immediately, so let's make sure.... + We do this before actually registering it, to make sure that a 'real' + IRQ doesn't run in parallel with our fake. */ + handler(irq, dev_id, &shirq_fakeregs); + } +#endif + retval = setup_irq(irq, action); if (retval) kfree(action); -- dwmw2