| Date | Fri, 30 Jul 2010 10:51:47 -0700 | From | Greg KH <> | Subject | [090/205] genirq: Deal with desc->set_type() changing desc->chip |
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2.6.34-stable review patch. If anyone has any objections, please let us know.
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From: Thomas Gleixner <tglx@linutronix.de>
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 <eha@doredevelopment.dk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: linuxppc-dev <linuxppc-dev@ozlabs.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- 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;
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