lkml.org 
[lkml]   [2012]   [Jun]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip:smp/hotplug] x86-smp-remove-call-to-ipi_call_lock-ipi_call_unlock
Commit-ID:  3b6f70fd7dd4e19fc674ec99e389bf0da5589525
Gitweb: http://git.kernel.org/tip/3b6f70fd7dd4e19fc674ec99e389bf0da5589525
Author: Yong Zhang <yong.zhang0@gmail.com>
AuthorDate: Tue, 29 May 2012 15:16:01 +0800
Committer: Thomas Gleixner <tglx@linutronix.de>
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@gmail.com>
Cc: ralf@linux-mips.org
Cc: sshtylyov@mvista.com
Cc: david.daney@cavium.com
Cc: nikunj@linux.vnet.ibm.com
Cc: paulmck@linux.vnet.ibm.com
Cc: axboe@kernel.dk
Cc: peterz@infradead.org
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1338275765-3217-7-git-send-email-yong.zhang0@gmail.com
Acked-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
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);


\
 
 \ /
  Last update: 2012-06-05 18:41    [W:1.070 / U:0.080 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site