linux-kernel - [PATCH 3/7] kvm,lapic: Justify use of swait

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Message-Id: <20170913200824.28067-4-dave@stgolabs.net>
Date:   Wed, 13 Sep 2017 13:08:20 -0700
From:   Davidlohr Bueso <dave@...olabs.net>
To:     mingo@...nel.org, peterz@...radead.org, pbonzini@...hat.com
Cc:     npiggin@...il.com, paulmck@...ux.vnet.ibm.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, dave@...olabs.net,
        Davidlohr Bueso <dbueso@...e.de>
Subject: [PATCH 3/7] kvm,lapic: Justify use of swait_activate()

A comment might serve future readers.

Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
---
 arch/x86/kvm/lapic.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index aaf10b6f5380..69c5612be786 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1324,6 +1324,10 @@ static void apic_timer_expired(struct kvm_lapic *apic)
 	atomic_inc(&apic->lapic_timer.pending);
 	kvm_set_pending_timer(vcpu);
 
+	/*
+	 * For x86, the atomic_inc() is serialized, thus
+	 * using swait_active() is safe.
+	 */
 	if (swait_active(q))
 		swake_up(q);
 
-- 
2.12.0