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Commit 0b17ba72 authored by Anton Blanchard's avatar Anton Blanchard Committed by Benjamin Herrenschmidt
Browse files

powerpc: check_and_cede_processor() never cedes 



Commit f948501b ("Make hard_irq_disable() actually hard-disable
interrupts") caused check_and_cede_processor to stop working.
->irq_happened will never be zero right after a hard_irq_disable
so the compiler removes the call to cede_processor completely.

The bug was introduced back in the lazy interrupt handling rework
of 3.4 but was hidden until recently because hard_irq_disable did
nothing.

This issue will eventually appear in 3.4 stable since the
hard_irq_disable fix is marked stable, so mark this one for stable
too.

Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 2d773aa4

arch/powerpc/include/asm/hw_irq.h

+5 −0
Original line number Original line Diff line number Diff line
@@ -103,6 +103,11 @@ static inline void hard_irq_disable(void) 
/* include/linux/interrupt.h needs hard_irq_disable to be a macro */

/* include/linux/interrupt.h needs hard_irq_disable to be a macro */

#define hard_irq_disable	hard_irq_disable

#define hard_irq_disable	hard_irq_disable





static inline bool lazy_irq_pending(void)

{

	return !!(get_paca()->irq_happened & ~PACA_IRQ_HARD_DIS);

}



/*

/*

 * This is called by asynchronous interrupts to conditionally

 * This is called by asynchronous interrupts to conditionally

 * re-enable hard interrupts when soft-disabled after having

 * re-enable hard interrupts when soft-disabled after having

arch/powerpc/platforms/pseries/processor_idle.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -106,7 +106,7 @@ static void check_and_cede_processor(void) 
	 * we first hard disable then check.

	 * we first hard disable then check.

	 */

	 */

	hard_irq_disable();

	hard_irq_disable();

	if (get_paca()->irq_happened == 0)

	if (!lazy_irq_pending())

		cede_processor();

		cede_processor();

}

}