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 <an...@samba.org>
Cc: sta...@vger.kernel.org
---
Index: linux-build/arch/powerpc/platforms/pseries/processor_idle.c
===================================================================
--- linux-build.orig/arch/powerpc/platforms/pseries/processor_idle.c
2012-06-27 21:20:45.403761715 +1000
+++ linux-build/arch/powerpc/platforms/pseries/processor_idle.c 2012-06-27
21:57:14.796788823 +1000
@@ -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 (get_paca()->irq_happened == PACA_IRQ_HARD_DIS)
cede_processor();
}
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