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Subject[PATCH 08/10] SPARC: smp: remove call to ipi_call_lock_irq()/ipi_call_unlock_irq()
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: "David S. Miller" <davem@davemloft.net>
Cc: sparclinux@vger.kernel.org
---
arch/sparc/kernel/smp_64.c | 6 ++----
1 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index f591598..60e745c 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -124,9 +124,9 @@ void __cpuinit smp_callin(void)
while (!cpumask_test_cpu(cpuid, &smp_commenced_mask))
rmb();

- ipi_call_lock_irq();
+ local_irq_disable();
set_cpu_online(cpuid, true);
- ipi_call_unlock_irq();
+ local_irq_enable();

/* idle thread is expected to have preempt disabled */
preempt_disable();
@@ -1308,9 +1308,7 @@ int __cpu_disable(void)
mdelay(1);
local_irq_disable();

- ipi_call_lock();
set_cpu_online(cpu, false);
- ipi_call_unlock();

cpu_map_rebuild();

--
1.7.5.4


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