Commit e04268b0 authored Mar 15, 2012 by Thomas Gleixner

genirq: Remove paranoid warnons and bogus fixups



Alexander pointed out that the warnons in the regular exit path are
bogus and the thread_mask one actually could be triggered when
__setup_irq() hands out that thread_mask again after __free_irq()
dropped irq_desc->lock.

Thinking more about it, neither IRQTF_RUNTHREAD nor the bit in
thread_mask can be set as this is the regular exit path. We come here
due to:
	__free_irq()
	   remove action from desc
	   synchronize_irq()
	   kthread_stop()

So synchronize_irq() makes sure that the thread finished running and
cleaned up both the thread_active count and thread_mask. After that
point nothing can set IRQTF_RUNTHREAD on this action. So the warnons
and the cleanups are pointless.

Reported-by: Alexander Gordeev <agordeev@redhat.com>
Cc: Ido Yariv <ido@wizery.com>
Link: http://lkml.kernel.org/r/20120315190755.GA6732@dhcp-26-207.brq.redhat.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

parent 7140ea19

kernel/irq/manage.c

+4 −10

Original line number	Diff line number	Diff line
		@@ -804,17 +804,11 @@ static int irq_thread(void *data)
		* This is the regular exit path. __free_irq() is stopping the
		* thread via kthread_stop() after calling
		* synchronize_irq(). So neither IRQTF_RUNTHREAD nor the
		* oneshot mask bit should be set.
		* oneshot mask bit can be set. We cannot verify that as we
		* cannot touch the oneshot mask at this point anymore as
		* __setup_irq() might have given out currents thread_mask
		* again.
		*
		* Verify that this is true.
		*/
		if (WARN_ON(test_and_clear_bit(IRQTF_RUNTHREAD, &action->thread_flags)))
		wake_threads_waitq(desc);

		if (WARN_ON(desc->threads_oneshot & action->thread_mask))
		irq_finalize_oneshot(desc, action, true);

		/*
		* Clear irq_thread. Otherwise exit_irq_thread() would make
		* fuzz about an active irq thread going into nirvana.
		*/