| From | Greg Kroah-Hartman <> | Subject | [ 009/187] powerpc: check_and_cede_processor() never cedes | Date | Thu, 12 Jul 2012 15:32:45 -0700 |
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From: Greg KH <gregkh@linuxfoundation.org>
3.4-stable review patch. If anyone has any objections, please let me know.
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From: Anton Blanchard <anton@samba.org>
commit 0b17ba7258db83cd02da560884e053b85de371f2 upstream.
Commit f948501b36c6 ("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: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/powerpc/include/asm/hw_irq.h | 5 +++++ arch/powerpc/platforms/pseries/processor_idle.c | 2 +- 2 files changed, 6 insertions(+), 1 deletion(-)
--- a/arch/powerpc/include/asm/hw_irq.h +++ b/arch/powerpc/include/asm/hw_irq.h @@ -102,6 +102,11 @@ static inline void hard_irq_disable(void /* include/linux/interrupt.h needs hard_irq_disable to be a macro */ #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 * re-enable hard interrupts when soft-disabled after having --- a/arch/powerpc/platforms/pseries/processor_idle.c +++ b/arch/powerpc/platforms/pseries/processor_idle.c @@ -106,7 +106,7 @@ static void check_and_cede_processor(voi * we first hard disable then check. */ hard_irq_disable(); - if (get_paca()->irq_happened == 0) + if (!lazy_irq_pending()) cede_processor(); }
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