linux-kernel - [PATCH v2 33/45] cris/smp: Use get/put_online_cpus

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Message-ID: <20130625203151.16593.6198.stgit@srivatsabhat.in.ibm.com>
Date:	Wed, 26 Jun 2013 02:01:51 +0530
From:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
To:	tglx@...utronix.de, peterz@...radead.org, tj@...nel.org,
	oleg@...hat.com, paulmck@...ux.vnet.ibm.com, rusty@...tcorp.com.au,
	mingo@...nel.org, akpm@...ux-foundation.org, namhyung@...nel.org,
	walken@...gle.com, vincent.guittot@...aro.org, laijs@...fujitsu.com
Cc:	rostedt@...dmis.org, wangyun@...ux.vnet.ibm.com,
	xiaoguangrong@...ux.vnet.ibm.com, sbw@....edu, fweisbec@...il.com,
	zhong@...ux.vnet.ibm.com, nikunj@...ux.vnet.ibm.com,
	srivatsa.bhat@...ux.vnet.ibm.com, linux-pm@...r.kernel.org,
	linux-arch@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Jesper Nilsson <jesper.nilsson@...s.com>,
	Mikael Starvik <starvik@...s.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-cris-kernel@...s.com,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Subject: [PATCH v2 33/45] cris/smp: Use get/put_online_cpus_atomic() to
 prevent CPU offline

Once stop_machine() is gone from the CPU offline path, we won't be able
to depend on disabling preemption to prevent CPUs from going offline
from under us.

Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going
offline, while invoking from atomic context.

Acked-by: Jesper Nilsson <jesper.nilsson@...s.com>
Cc: Mikael Starvik <starvik@...s.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-cris-kernel@...s.com
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
---

 arch/cris/arch-v32/kernel/smp.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/cris/arch-v32/kernel/smp.c b/arch/cris/arch-v32/kernel/smp.c
index cdd1202..b2d4612 100644
--- a/arch/cris/arch-v32/kernel/smp.c
+++ b/arch/cris/arch-v32/kernel/smp.c
@@ -13,6 +13,7 @@
 #include <linux/init.h>
 #include <linux/timex.h>
 #include <linux/sched.h>
+#include <linux/cpu.h>
 #include <linux/kernel.h>
 #include <linux/cpumask.h>
 #include <linux/interrupt.h>
@@ -222,6 +223,7 @@ void flush_tlb_common(struct mm_struct* mm, struct vm_area_struct* vma, unsigned
 	unsigned long flags;
 	cpumask_t cpu_mask;
 
+	get_online_cpus_atomic();
 	spin_lock_irqsave(&tlbstate_lock, flags);
 	cpu_mask = (mm == FLUSH_ALL ? cpu_all_mask : *mm_cpumask(mm));
 	cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
@@ -230,6 +232,7 @@ void flush_tlb_common(struct mm_struct* mm, struct vm_area_struct* vma, unsigned
 	flush_addr = addr;
 	send_ipi(IPI_FLUSH_TLB, 1, cpu_mask);
 	spin_unlock_irqrestore(&tlbstate_lock, flags);
+	put_online_cpus_atomic();
 }
 
 void flush_tlb_all(void)
@@ -319,10 +322,12 @@ int smp_call_function(void (*func)(void *info), void *info, int wait)
 	data.info = info;
 	data.wait = wait;
 
+	get_online_cpus_atomic();
 	spin_lock(&call_lock);
 	call_data = &data;
 	ret = send_ipi(IPI_CALL, wait, cpu_mask);
 	spin_unlock(&call_lock);
+	put_online_cpus_atomic();
 
 	return ret;
 }

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