On Tue, May 29, 2012 at 01:31:54PM +0530, Srivatsa S. Bhat wrote:
> This looks odd. IRQs must not have been enabled at this point.
> Just remove the call to local_irq_enable() that is found a few lines above
> this line and then you won't have to add this call to local_irq_disable().
Yeah, have thought about it. But because I was not sure there is
special need to enalbe irq that early (don't know much about sparc),
I decided to make minor change :)
Since we have gotten confirmation from David, I'm sending out the
new version. Please check it.
Thanks,
Yong
---
From: Yong Zhang <yong.zhang@xxxxxxxxxxxxx>
Date: Tue, 29 May 2012 12:56:08 +0800
Subject: [UPDATED] [RFC PATCH 8/10] SPARC: smp: remove call to
ipi_call_lock_irq()/ipi_call_unlock_irq()
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.
And also delay irq enable to after set_cpu_online().
Signed-off-by: Yong Zhang <yong.zhang0@xxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: sparclinux@xxxxxxxxxxxxxxx
---
arch/sparc/kernel/smp_64.c | 7 +------
1 files changed, 1 insertions(+), 6 deletions(-)
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index f591598..781bcb1 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -103,8 +103,6 @@ void __cpuinit smp_callin(void)
if (cheetah_pcache_forced_on)
cheetah_enable_pcache();
- local_irq_enable();
-
callin_flag = 1;
__asm__ __volatile__("membar #Sync\n\t"
"flush %%g6" : : : "memory");
@@ -124,9 +122,8 @@ void __cpuinit smp_callin(void)
while (!cpumask_test_cpu(cpuid, &smp_commenced_mask))
rmb();
- ipi_call_lock_irq();
set_cpu_online(cpuid, true);
- ipi_call_unlock_irq();
+ local_irq_enable();
/* idle thread is expected to have preempt disabled */
preempt_disable();
@@ -1308,9 +1305,7 @@ 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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