From: Davidlohr Bueso <dave@stgolabs.net>
To: mingo@redhat.com, peterz@infradead.org, pbonzini@redhat.com
Cc: npiggin@gmail.com, paulmck@linux.vnet.ibm.com, dave@stgolabs.net,
linux-kernel@vger.kernel.org, Davidlohr Bueso <dbueso@suse.de>
Subject: [PATCH 3/6] kvm,lapic: Justify use of swait_activate()
Date: Tue, 5 Sep 2017 12:00:19 -0700 [thread overview]
Message-ID: <20170905190022.1474-4-dave@stgolabs.net> (raw)
In-Reply-To: <20170905190022.1474-1-dave@stgolabs.net>
A comment might serve future readers.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
---
arch/x86/kvm/lapic.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 589dcc117086..fb8be28c7093 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1326,6 +1326,12 @@ static void apic_timer_expired(struct kvm_lapic *apic)
atomic_inc(&apic->lapic_timer.pending);
kvm_set_pending_timer(vcpu);
+ /*
+ * The above kvm_set_pending_timer implies a wmb
+ * which pairs with the swaiter side. Either way,
+ * the atomic_inc() is also serialized so using
+ * swait_active() is safe.
+ */
if (swait_active(q))
swake_up(q);
--
2.12.0
next prev parent reply other threads:[~2017-09-05 19:03 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-05 19:00 [PATCH 0/6] swait: Introduce and use swq_has_sleepers Davidlohr Bueso
2017-09-05 19:00 ` [PATCH 1/6] sched/wait: Add swq_has_sleepers() Davidlohr Bueso
2017-10-11 8:27 ` Peter Zijlstra
2017-10-11 11:21 ` Paolo Bonzini
2017-10-11 11:29 ` Peter Zijlstra
2017-09-05 19:00 ` [PATCH 2/6] kvm,async_pf: Use swq_has_sleepers() Davidlohr Bueso
2017-09-05 19:00 ` Davidlohr Bueso [this message]
2017-09-05 19:00 ` [PATCH 4/6] x86,kvm: Fix apf_task_wake_one() serialization Davidlohr Bueso
2017-09-10 9:20 ` Paolo Bonzini
2017-09-10 9:24 ` Paolo Bonzini
2017-10-12 8:23 ` Peter Zijlstra
2017-09-05 19:00 ` [PATCH 5/6] kvm: Serialize wq active checks in kvm_vcpu_wake_up() Davidlohr Bueso
2017-09-05 19:00 ` [PATCH 6/6] kvm,powerpc: Serialize wq active checks in ops->vcpu_kick Davidlohr Bueso
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