From 92ea77275b5345c1300433f28689493dc4163f24 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Thu, 24 May 2007 08:37:14 -0700 Subject: [PATCH] Fix crash with irqpoll due to the IRQF_IRQPOLL flag testing With irqpoll enabled, trying to test the IRQF_IRQPOLL flag in the actions would cause a NULL pointer dereference if no action was installed (for example, the driver might have been unloaded with interrupts still pending). So be a bit more careful about testing the flag by making sure to test for that case. (The actual _change_ is trivial, the patch is more than a one-liner because I rewrote the testing to also be much more readable. Original (discarded) bugfix by Bernhard Walle. Cc: Bernhard Walle Tested-by: Vivek Goyal Signed-off-by: Linus Torvalds --- kernel/irq/spurious.c | 46 ++++++++++++++++++++++++++++++++++--------- 1 file changed, 37 insertions(+), 9 deletions(-) diff --git a/kernel/irq/spurious.c b/kernel/irq/spurious.c index b0d81aae47..bd9e272d55 100644 --- a/kernel/irq/spurious.c +++ b/kernel/irq/spurious.c @@ -135,6 +135,39 @@ report_bad_irq(unsigned int irq, struct irq_desc *desc, irqreturn_t action_ret) } } +static inline int try_misrouted_irq(unsigned int irq, struct irq_desc *desc, irqreturn_t action_ret) +{ + struct irqaction *action; + + if (!irqfixup) + return 0; + + /* We didn't actually handle the IRQ - see if it was misrouted? */ + if (action_ret == IRQ_NONE) + return 1; + + /* + * But for 'irqfixup == 2' we also do it for handled interrupts if + * they are marked as IRQF_IRQPOLL (or for irq zero, which is the + * traditional PC timer interrupt.. Legacy) + */ + if (irqfixup < 2) + return 0; + + if (!irq) + return 1; + + /* + * Since we don't get the descriptor lock, "action" can + * change under us. We don't really care, but we don't + * want to follow a NULL pointer. So tell the compiler to + * just load it once by using a barrier. + */ + action = desc->action; + barrier(); + return action && (action->flags & IRQF_IRQPOLL); +} + void note_interrupt(unsigned int irq, struct irq_desc *desc, irqreturn_t action_ret) { @@ -144,15 +177,10 @@ void note_interrupt(unsigned int irq, struct irq_desc *desc, report_bad_irq(irq, desc, action_ret); } - if (unlikely(irqfixup)) { - /* Don't punish working computers */ - if ((irqfixup == 2 && ((irq == 0) || - (desc->action->flags & IRQF_IRQPOLL))) || - action_ret == IRQ_NONE) { - int ok = misrouted_irq(irq); - if (action_ret == IRQ_NONE) - desc->irqs_unhandled -= ok; - } + if (unlikely(try_misrouted_irq(irq, desc, action_ret))) { + int ok = misrouted_irq(irq); + if (action_ret == IRQ_NONE) + desc->irqs_unhandled -= ok; } desc->irq_count++; -- 2.39.5