From patchwork Fri Jul 30 17:51:47 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [090/205] genirq: Deal with desc->set_type() changing desc->chip From: gregkh@suse.de X-Patchwork-Id: 60373 Message-Id: <20100730175141.815256382@clark.site> To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, linuxppc-dev , Thomas Gleixner , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk Date: Fri, 30 Jul 2010 10:51:47 -0700 2.6.34-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 @@ -440,6 +440,9 @@ 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;