[tip:smp/hotplug] x86-smp-remove-call-to-ipi_call_lock-ipi_call_unlock
From: tip-bot for Yong Zhang
Date: Tue Jun 05 2012 - 11:51:09 EST
Commit-ID: 3b6f70fd7dd4e19fc674ec99e389bf0da5589525
Gitweb: http://git.kernel.org/tip/3b6f70fd7dd4e19fc674ec99e389bf0da5589525
Author: Yong Zhang <yong.zhang0@xxxxxxxxx>
AuthorDate: Tue, 29 May 2012 15:16:01 +0800
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Tue, 5 Jun 2012 17:27:12 +0200
x86-smp-remove-call-to-ipi_call_lock-ipi_call_unlock
ipi_call_lock/unlock() lock resp. unlock call_function.lock. This lock
protects only the call_function data structure itself, but it's
completely unrelated to cpu_online_mask. The mask to which the IPIs
are sent is calculated before call_function.lock is taken in
smp_call_function_many(), so the locking around set_cpu_online() is
pointless and can be removed.
[ tglx: Massaged changelog ]
Signed-off-by: Yong Zhang <yong.zhang0@xxxxxxxxx>
Cc: ralf@xxxxxxxxxxxxxx
Cc: sshtylyov@xxxxxxxxxx
Cc: david.daney@xxxxxxxxxx
Cc: nikunj@xxxxxxxxxxxxxxxxxx
Cc: paulmck@xxxxxxxxxxxxxxxxxx
Cc: axboe@xxxxxxxxx
Cc: peterz@xxxxxxxxxxxxx
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1338275765-3217-7-git-send-email-yong.zhang0@xxxxxxxxx
Acked-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
Acked-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
arch/x86/kernel/smpboot.c | 9 ---------
arch/x86/xen/smp.c | 2 --
2 files changed, 0 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index f56f96d..b2fd28f 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -255,22 +255,13 @@ notrace static void __cpuinit start_secondary(void *unused)
check_tsc_sync_target();
/*
- * We need to hold call_lock, so there is no inconsistency
- * between the time smp_call_function() determines number of
- * IPI recipients, and the time when the determination is made
- * for which cpus receive the IPI. Holding this
- * lock helps us to not include this cpu in a currently in progress
- * smp_call_function().
- *
* We need to hold vector_lock so there the set of online cpus
* does not change while we are assigning vectors to cpus. Holding
* this lock ensures we don't half assign or remove an irq from a cpu.
*/
- ipi_call_lock();
lock_vector_lock();
set_cpu_online(smp_processor_id(), true);
unlock_vector_lock();
- ipi_call_unlock();
per_cpu(cpu_state, smp_processor_id()) = CPU_ONLINE;
x86_platform.nmi_init();
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index afb250d..f58dca7 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -80,9 +80,7 @@ static void __cpuinit cpu_bringup(void)
notify_cpu_starting(cpu);
- ipi_call_lock();
set_cpu_online(cpu, true);
- ipi_call_unlock();
this_cpu_write(cpu_state, CPU_ONLINE);
--
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