From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from coco.kroah.org (kroah.org [198.145.64.141]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "coco.kroah.org", Issuer "Greg KH" (not verified)) by ozlabs.org (Postfix) with ESMTPS id D9C05B6F14 for ; Sat, 31 Jul 2010 03:35:08 +1000 (EST) Message-Id: <20100730173109.573358136@clark.site> Date: Fri, 30 Jul 2010 10:30:41 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Subject: [076/140] genirq: Deal with desc->set_type() changing desc->chip In-Reply-To: <20100730173205.GA22581@kroah.com> Cc: stable-review@kernel.org, linuxppc-dev , Thomas Gleixner , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 2.6.33-stable review patch. If anyone has any objections, please let us know. ------------------ From: Thomas Gleixner commit 4673247562e39a17e09440fa1400819522ccd446 upstream. The set_type() function can change the chip implementation when the trigger mode changes. That might result in using an non-initialized irq chip when called from __setup_irq() or when called via set_irq_type() on an already enabled irq. The set_irq_type() function should not be called on an enabled irq, but because we forgot to put a check into it, we have a bunch of users which grew the habit of doing that and it never blew up as the function is serialized via desc->lock against all users of desc->chip and they never hit the non-initialized irq chip issue. The easy fix for the __setup_irq() issue would be to move the irq_chip_set_defaults(desc->chip) call after the trigger setting to make sure that a chip change is covered. But as we have already users, which do the type setting after request_irq(), the safe fix for now is to call irq_chip_set_defaults() from __irq_set_trigger() when desc->set_type() changed the irq chip. It needs a deeper analysis whether we should refuse to change the chip on an already enabled irq, but that'd be a large scale change to fix all the existing users. So that's neither stable nor 2.6.35 material. Reported-by: Esben Haabendal Signed-off-by: Thomas Gleixner Cc: Benjamin Herrenschmidt Cc: linuxppc-dev Signed-off-by: Greg Kroah-Hartman --- kernel/irq/manage.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -436,6 +436,9 @@ int __irq_set_trigger(struct irq_desc *d /* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */ desc->status &= ~(IRQ_LEVEL | IRQ_TYPE_SENSE_MASK); desc->status |= flags; + + if (chip != desc->chip) + irq_chip_set_defaults(desc->chip); } return ret;