sparc64: Prevent sparc64 from invoking irq handlers on offline CPUs

Make sparc64 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@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/sparc64/kernel/smp.c b/arch/sparc64/kernel/smp.c
index 0712a44..2be166c 100644 (file)
--- a/arch/sparc64/kernel/smp.c
+++ b/arch/sparc64/kernel/smp.c
@@ -1303,10 +1303,6 @@ int __cpu_disable(void)
        c->core_id = 0;
        c->proc_id = -1;
 
-       ipi_call_lock();
-       cpu_clear(cpu, cpu_online_map);
-       ipi_call_unlock();
-
        smp_wmb();
 
        /* Make sure no interrupts point to this cpu.  */
@@ -1316,6 +1312,10 @@ int __cpu_disable(void)
        mdelay(1);
        local_irq_disable();
 
+       ipi_call_lock();
+       cpu_clear(cpu, cpu_online_map);
+       ipi_call_unlock();
+
        return 0;
 }