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authorAnton Blanchard <anton@samba.org>2012-06-27 13:13:52 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2012-06-29 14:35:37 +1000
commit0b17ba7258db83cd02da560884e053b85de371f2 (patch)
tree970b6d210323d31f037c8593fd325636ec40a843
parent2d773aa4810d4a612d1c879faacc38594cc3f841 (diff)
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 <anton@samba.org> Cc: stable@vger.kernel.org Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
-rw-r--r--arch/powerpc/include/asm/hw_irq.h5
-rw-r--r--arch/powerpc/platforms/pseries/processor_idle.c2
2 files changed, 6 insertions, 1 deletions
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();
}