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genirq: Plug race in report_bad_irq() 

We cannot walk the action chain unlocked. Even if IRQ_INPROGRESS is
set an action can be removed and we follow a null pointer. It's safe
to take the lock there, because the code which removes the action will
call synchronize_irq() which waits unlocked for IRQ_INPROGRESS going
away.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
hifive-unleashed-5.1
Thomas Gleixner 2011-02-07 09:05:05 +01:00
parent 2b879eaf09
commit 1082687e8d
1 changed files with 9 additions and 3 deletions
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12
kernel/irq/spurious.c
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@ -139,15 +139,13 @@ static void poll_spurious_irqs(unsigned long dummy)
*
* (The other 100-of-100,000 interrupts may have been a correctly
* functioning device sharing an IRQ with the failing one)
*
* Called under desc->lock
*/
static void
__report_bad_irq(unsigned int irq, struct irq_desc *desc,
irqreturn_t action_ret)
{
struct irqaction *action;
unsigned long flags;
if (action_ret != IRQ_HANDLED && action_ret != IRQ_NONE) {
printk(KERN_ERR "irq event %d: bogus return value %x\n",
@ -159,6 +157,13 @@ __report_bad_irq(unsigned int irq, struct irq_desc *desc,
dump_stack();
printk(KERN_ERR "handlers:\n");
/*
* We need to take desc->lock here. note_interrupt() is called
* w/o desc->lock held, but IRQ_PROGRESS set. We might race
* with something else removing an action. It's ok to take
* desc->lock here. See synchronize_irq().
*/
raw_spin_lock_irqsave(&desc->lock, flags);
action = desc->action;
while (action) {
printk(KERN_ERR "[<%p>]", action->handler);
@ -167,6 +172,7 @@ __report_bad_irq(unsigned int irq, struct irq_desc *desc,
printk("\n");
action = action->next;
}
raw_spin_unlock_irqrestore(&desc->lock, flags);
}
static void