[PATCH] prevent powerpc from invoking irq handlers on offline CPUs

From: Paul E. McKenney
Date: Sun Aug 31 2008 - 13:31:39 EST


Make powerpc refrain from clearing a given to-be-offlined CPU's bit in the
cpu_online_mask until it has processed pending irqs. This change
prevents other CPUs from being blindsided by an apparently offline CPU
nevertheless changing globally visible state.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---

smp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 5337ca7..1fedd7d 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -250,11 +250,11 @@ int generic_cpu_disable(void)
if (cpu == boot_cpuid)
return -EBUSY;

- cpu_clear(cpu, cpu_online_map);
#ifdef CONFIG_PPC64
vdso_data->processorCount--;
fixup_irqs(cpu_online_map);
#endif
+ cpu_clear(cpu, cpu_online_map);
return 0;
}

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