linux

iv/linux

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Thomas Gleixner abc7e40c81 genirq: Prevent chip buslock deadlock

If a interrupt chip utilizes chip->buslock then free_irq() can
deadlock in the following way:

CPU0				CPU1
				interrupt(X) (Shared or spurious)
free_irq(X)			interrupt_thread(X)
chip_bus_lock(X)
				   irq_finalize_oneshot(X)
				     chip_bus_lock(X)
synchronize_irq(X)
	
synchronize_irq() waits for the interrupt thread to complete,
i.e. forever.

Solution is simple: Drop chip_bus_lock() before calling
synchronize_irq() as we do with the irq_desc lock. There is nothing to
be protected after the point where irq_desc lock has been released.

This adds chip_bus_lock/unlock() to the remove_irq() code path, but
that's actually correct in the case where remove_irq() is called on
such an interrupt. The current users of remove_irq() are not affected
as none of those interrupts is on a chip which requires buslock.

Reported-by: Fredrik Markström <fredrik.markstrom@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org

2015-12-14 09:45:06 +01:00

autoprobe.c

genirq: Handle pending irqs in irq_startup()

2012-02-15 11:56:59 +01:00

chip.c

genirq: Add flag to force mask in disable_irq[_nosync]()

2015-10-11 11:33:42 +02:00

cpuhotplug.c

genirq: Make the cpuhotplug migration code less noisy

2015-10-22 14:34:57 +02:00

debug.h

irq: hide debug macros so they don't collide with others.