From 0b17ba7258db83cd02da560884e053b85de371f2 Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Wed, 27 Jun 2012 13:13:52 +0000 Subject: [PATCH] powerpc: check_and_cede_processor() never cedes 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 Cc: stable@vger.kernel.org Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/hw_irq.h | 5 +++++ arch/powerpc/platforms/pseries/processor_idle.c | 2 +- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/hw_irq.h b/arch/powerpc/include/asm/hw_irq.h index 32b394f3b854..6eb75b80488c 100644 --- a/arch/powerpc/include/asm/hw_irq.h +++ b/arch/powerpc/include/asm/hw_irq.h @@ -103,6 +103,11 @@ 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 diff --git a/arch/powerpc/platforms/pseries/processor_idle.c b/arch/powerpc/platforms/pseries/processor_idle.c index 41a34bc4a9a2..e61483e8e960 100644 --- 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(void) * we first hard disable then check. */ hard_irq_disable(); - if (get_paca()->irq_happened == 0) + if (!lazy_irq_pending()) cede_processor(); } -- 2.20.1