From 1082687e8d6292a61759eb83358e7db39fed1bf4 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 7 Feb 2011 09:05:05 +0100 Subject: [PATCH] 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 --- kernel/irq/spurious.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/kernel/irq/spurious.c b/kernel/irq/spurious.c index 3089d3b9d5f3..2fbfda2716e1 100644 --- a/kernel/irq/spurious.c +++ b/kernel/irq/spurious.c @@ -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 -- 2.20.1