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From: Davidlohr Bueso <dave@stgolabs.net>
To: mingo@kernel.org, peterz@infradead.org, pbonzini@redhat.com
Cc: npiggin@gmail.com, paulmck@linux.vnet.ibm.com,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	dave@stgolabs.net, Davidlohr Bueso <dbueso@suse.de>
Subject: [PATCH 3/7] kvm,lapic: Justify use of swait_activate()
Date: Wed, 13 Sep 2017 13:08:20 -0700	[thread overview]
Message-ID: <20170913200824.28067-4-dave@stgolabs.net> (raw)
In-Reply-To: <20170913200824.28067-1-dave@stgolabs.net>

A comment might serve future readers.

Signed-off-by: Davidlohr Bueso <dbueso@suse.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

  parent reply	other threads:[~2017-09-13 20:10 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-13 20:08 [PATCH v2 0/7] swait: Introduce and use swq_has_sleeper() Davidlohr Bueso
2017-09-13 20:08 ` [PATCH 1/7] sched/wait: Add swq_has_sleepers() Davidlohr Bueso
2017-09-13 20:08 ` [PATCH 2/7] kvm,async_pf: Use swq_has_sleepers() Davidlohr Bueso
2017-09-13 20:08 ` Davidlohr Bueso [this message]
2017-09-15 11:47   ` [PATCH 3/7] kvm,lapic: Justify use of swait_activate() Paolo Bonzini
2017-09-13 20:08 ` [PATCH 4/7] kvm,x86: Fix apf_task_wake_one() wq serialization Davidlohr Bueso
2017-09-13 20:08 ` [PATCH 5/7] kvm: Serialize wq active checks in kvm_vcpu_wake_up() Davidlohr Bueso
2017-09-13 20:08 ` [PATCH 6/7] kvm,powerpc: Serialize wq active checks in ops->vcpu_kick Davidlohr Bueso
2017-09-13 20:08 ` [PATCH 7/7] kvm,mips: Fix potential swait_active() races Davidlohr Bueso
2017-09-13 20:35   ` Paolo Bonzini
2017-09-13 22:22     ` Davidlohr Bueso
2017-09-15 11:33       ` Paolo Bonzini
2017-09-15 11:53 ` [PATCH v2 0/7] swait: Introduce and use swq_has_sleeper() Paolo Bonzini
2017-09-19  8:25   ` Christian Borntraeger

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