[PATCH 5/7] kvm: Serialize wq active checks in kvm_vcpu_wake_up()

From	Davidlohr Bueso <dave@stgolabs.net>
Newsgroups	linux.kernel
Subject	[PATCH 5/7] kvm: Serialize wq active checks in kvm_vcpu_wake_up()
Date	2017-09-13 22:10 +0200
Message-ID	<upm8V-3w4-7@gated-at.bofh.it> (permalink)
References	<upm8V-3w4-9@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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This is a generic call and can be suceptible to races
in reading the wq task_list while another task is adding
itself to the list. Add a full barrier by using the
swq_has_sleeper() helper.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
---
 virt/kvm/kvm_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 6ed1c2021198..c41d903c5783 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2186,7 +2186,7 @@ bool kvm_vcpu_wake_up(struct kvm_vcpu *vcpu)
 	struct swait_queue_head *wqp;
 
 	wqp = kvm_arch_vcpu_wq(vcpu);
-	if (swait_active(wqp)) {
+	if (swq_has_sleeper(wqp)) {
 		swake_up(wqp);
 		++vcpu->stat.halt_wakeup;
 		return true;
-- 
2.12.0

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[PATCH 5/7] kvm: Serialize wq active checks in kvm_vcpu_wake_up() Davidlohr Bueso <dave@stgolabs.net> - 2017-09-13 22:10 +0200

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