projects/linux·commit 2d860ad7

genirq: prevent wakeup of freed irq thread

2d860ad7 · Linus Torvalds <[email protected]> · 2009-08-13 13:05:10 -07:00

free_irq() can remove an irqaction while the corresponding interrupt
is in progress, but free_irq() sets action->thread to NULL
unconditionally, which might lead to a NULL pointer dereference in
handle_IRQ_event() when the hard interrupt context tries to wake up
the handler thread.

Prevent this by moving the thread stop after synchronize_irq(). No
need to set action->thread to NULL either as action is going to be
freed anyway.

This fixes a boot crash reported against preempt-rt which uses the
mainline irq threads code to implement full irq threading.

[ tglx: removed local irqthread variable ]

Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Commit
2d860ad76f4ee4d2eba0fe3797c8d7cdce432cc0
Parents
3493e84d

Changes

1 files changed · +7 −10

FileStatusAddDelContent
kernel/irq/manage.cmodified+7−10View file

kernel/irq/manage.c

View file
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 61c679d..d222515 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -761,7 +761,6 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
{
struct irq_desc *desc = irq_to_desc(irq);
struct irqaction *action, **action_ptr;
- struct task_struct *irqthread;
unsigned long flags;
WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
@@ -809,9 +808,6 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
desc->chip->disable(irq);
}
- irqthread = action->thread;
- action->thread = NULL;
-
spin_unlock_irqrestore(&desc->lock, flags);
unregister_handler_proc(irq, action);
@@ -819,12 +815,6 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
/* Make sure it's not being used on another CPU: */
synchronize_irq(irq);
- if (irqthread) {
- if (!test_bit(IRQTF_DIED, &action->thread_flags))
- kthread_stop(irqthread);
- put_task_struct(irqthread);
- }
-
#ifdef CONFIG_DEBUG_SHIRQ
/*
* It's a shared IRQ -- the driver ought to be prepared for an IRQ
@@ -840,6 +830,13 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
local_irq_restore(flags);
}
#endif
+
+ if (action->thread) {
+ if (!test_bit(IRQTF_DIED, &action->thread_flags))
+ kthread_stop(action->thread);
+ put_task_struct(action->thread);
+ }
+
return action;
}