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Subject[RFC PATCH 09/10] POWERPC: smp: remove call to ipi_call_lock()/ipi_call_unlock()
Date
From: Yong Zhang <yong.zhang@windriver.com>

1) call_function.lock used in smp_call_function_many() is just to protect
call_function.queue and &data->refs, cpu_online_mask is outside of the
lock. And it's not necessary to protect cpu_online_mask,
because data->cpumask is pre-calculate and even if a cpu is brougt up
when calling arch_send_call_function_ipi_mask(), it's harmless because
validation test in generic_smp_call_function_interrupt() will take care
of it.

2) For cpu down issue, stop_machine() will guarantee that no concurrent
smp_call_fuction() is processing.

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org
---
arch/powerpc/kernel/smp.c | 2 --
1 files changed, 0 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index e4cb343..e1417c4 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -571,7 +571,6 @@ void __devinit start_secondary(void *unused)
if (system_state == SYSTEM_RUNNING)
vdso_data->processorCount++;
#endif
- ipi_call_lock();
notify_cpu_starting(cpu);
set_cpu_online(cpu, true);
/* Update sibling maps */
@@ -601,7 +600,6 @@ void __devinit start_secondary(void *unused)
of_node_put(np);
}
of_node_put(l2_cache);
- ipi_call_unlock();

local_irq_enable();

--
1.7.5.4


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