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genirq: Get rid of unnecessary IRQTF_DIED flag

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Currently IRQTF_DIED flag is set when a IRQ thread handler calls do_exit()
But also PF_EXITING per process flag gets set when a thread exits. This
fix eliminates the duplicate by using PF_EXITING flag.

Also, there is a race condition in exit_irq_thread(). In case a thread's
bit is cleared in desc->threads_oneshot (and the IRQ line gets unmasked),
but before IRQTF_DIED flag is set, a new interrupt might come in and set
just cleared bit again, this time forever. This fix throws IRQTF_DIED flag
away, eliminating the race as a result.

[ tglx: Test THREAD_EXITING first as suggested by Oleg ]

Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Link: http://lkml.kernel.org/r/20120309135958.GD2114@dhcp-26-207.brq.redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Alexander Gordeev
2012-03-09 14:59:59 +01:00
committed by Thomas Gleixner
parent 05d74efa3c
commit 5234ffb9f7
4 changed files with 4 additions and 15 deletions
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11
kernel/irq/manage.c
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@@ -845,17 +845,8 @@ void exit_irq_thread(void)
desc = irq_to_desc(action->irq);
/*
* Prevent a stale desc->threads_oneshot. Must be called
* before setting the IRQTF_DIED flag.
*/
/* Prevent a stale desc->threads_oneshot */
irq_finalize_oneshot(desc, action, true);
/*
* Set the THREAD DIED flag to prevent further wakeups of the
* soon to be gone threaded handler.
*/
set_bit(IRQTF_DIED, &action->flags);
}
static void irq_setup_forced_threading(struct irqaction *new)