linux-kernel - [PATCH] arm, kvm: fix double lock on cpu_add_remove

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Date:	Mon,  7 Apr 2014 01:36:08 +0800
From:	Ming Lei <tom.leiming@...il.com>
To:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	Ming Lei <tom.leiming@...il.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Christoffer Dall <christoffer.dall@...aro.org>,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH] arm, kvm: fix double lock on cpu_add_remove_lock

The patch of "arm, kvm: Fix CPU hotplug callback registration"
in -next tree holds the lock before calling the two functions:

	kvm_vgic_hyp_init()
	kvm_timer_hyp_init()

and both the two functions are calling register_cpu_notifier()
to register cpu notifier, so cause double lock on cpu_add_remove_lock.

Considered that both two functions are only called inside
kvm_arch_init() with holding cpu_add_remove_lock, so simply use
__register_cpu_notifier() to fix the problem.

Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Christoffer Dall <christoffer.dall@...aro.org>
Cc: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Ming Lei <tom.leiming@...il.com>
---
 virt/kvm/arm/arch_timer.c |    2 +-
 virt/kvm/arm/vgic.c       |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index 5081e80..22fa819 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -277,7 +277,7 @@ int kvm_timer_hyp_init(void)
 
 	host_vtimer_irq = ppi;
 
-	err = register_cpu_notifier(&kvm_timer_cpu_nb);
+	err = __register_cpu_notifier(&kvm_timer_cpu_nb);
 	if (err) {
 		kvm_err("Cannot register timer CPU notifier\n");
 		goto out_free;
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 8ca405c..47b2983 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1496,7 +1496,7 @@ int kvm_vgic_hyp_init(void)
 		goto out;
 	}
 
-	ret = register_cpu_notifier(&vgic_cpu_nb);
+	ret = __register_cpu_notifier(&vgic_cpu_nb);
 	if (ret) {
 		kvm_err("Cannot register vgic CPU notifier\n");
 		goto out_free_irq;
-- 
1.7.9.5

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