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Message-Id: <1338275765-3217-5-git-send-email-yong.zhang0@gmail.com>
Date: Tue, 29 May 2012 15:15:59 +0800
From: Yong Zhang <yong.zhang0@...il.com>
To: linux-kernel@...r.kernel.org
Cc: ralf@...ux-mips.org, sshtylyov@...sta.com, david.daney@...ium.com,
nikunj@...ux.vnet.ibm.com, paulmck@...ux.vnet.ibm.com,
axboe@...nel.dk, mingo@...nel.org, tglx@...utronix.de,
peterz@...radead.org, akpm@...ux-foundation.org,
srivatsa.bhat@...ux.vnet.ibm.com,
Martin Schwidefsky <schwidefsky@...ibm.com>,
Heiko Carstens <heiko.carstens@...ibm.com>,
linux390@...ibm.com, linux-s390@...r.kernel.org
Subject: [RFC PATCH 04/10] S390: smp: remove call to ipi_call_lock()/ipi_call_unlock()
From: Yong Zhang <yong.zhang@...driver.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@...il.com>
Cc: Martin Schwidefsky <schwidefsky@...ibm.com>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: linux390@...ibm.com
Cc: linux-s390@...r.kernel.org
---
arch/s390/kernel/smp.c | 2 --
1 files changed, 0 insertions(+), 2 deletions(-)
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 647ba94..14c8a08 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -716,9 +716,7 @@ static void __cpuinit smp_start_secondary(void *cpuvoid)
init_cpu_vtimer();
pfault_init();
notify_cpu_starting(smp_processor_id());
- ipi_call_lock();
set_cpu_online(smp_processor_id(), true);
- ipi_call_unlock();
local_irq_enable();
/* cpu_idle will call schedule for us */
cpu_idle();
--
1.7.5.4
--
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