linux-kernel - [PATCH v2 02/14] KVM: x86: simplify atomics in kvm_pit_ack

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Message-Id: <1455736496-374-3-git-send-email-rkrcmar@redhat.com>
Date:	Wed, 17 Feb 2016 20:14:44 +0100
From:	Radim Krčmář <rkrcmar@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
	Yuki Shibuya <shibuya.yk@...s.nec.co.jp>
Subject: [PATCH v2 02/14] KVM: x86: simplify atomics in kvm_pit_ack_irq

We already have a helper that does the same thing.

Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>
---
 v2: The pending == 1 means there's only us => don't reinject.

 arch/x86/kvm/i8254.c | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index ab5318727579..7d694ac7f4a4 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -236,19 +236,9 @@ static void kvm_pit_ack_irq(struct kvm_irq_ack_notifier *kian)
 {
 	struct kvm_kpit_state *ps = container_of(kian, struct kvm_kpit_state,
 						 irq_ack_notifier);
-	int value;
 
 	spin_lock(&ps->inject_lock);
-	value = atomic_dec_return(&ps->pending);
-	if (value < 0)
-		/* spurious acks can be generated if, for example, the
-		 * PIC is being reset.  Handle it gracefully here
-		 */
-		atomic_inc(&ps->pending);
-	else if (value > 0 && ps->reinject)
-		/* in this case, we had multiple outstanding pit interrupts
-		 * that we needed to inject.  Reinject
-		 */
+	if (atomic_dec_if_positive(&ps->pending) > 0 && ps->reinject)
 		queue_kthread_work(&ps->pit->worker, &ps->pit->expired);
 	ps->irq_ack = 1;
 	spin_unlock(&ps->inject_lock);
-- 
2.7.1