From: Jan Kiszka <jan.kiszka@siemens.com>
To: Avi Kivity <avi@redhat.com>
Cc: kvm-devel <kvm@vger.kernel.org>, Marcelo Tosatti <mtosatti@redhat.com>
Subject: [PATCH v2 2/2] kvm: x86: Drop useless atomic test from timer function
Date: Tue, 09 Jun 2009 15:37:03 +0200 [thread overview]
Message-ID: <4A2E657F.8080908@siemens.com> (raw)
In-Reply-To: <4A2E2B3B.5020408@siemens.com>
The current code tries to optimize the setting of KVM_REQ_PENDING_TIMER
but used atomic_inc_and_test - which always returns true unless pending
had the invalid value of -1 on entry. This patch drops the test part
preserving the original semantic but expressing it less confusingly.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
arch/x86/kvm/timer.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/timer.c b/arch/x86/kvm/timer.c
index 36054e9..8dd1a55 100644
--- a/arch/x86/kvm/timer.c
+++ b/arch/x86/kvm/timer.c
@@ -15,9 +15,9 @@ static int __kvm_timer_fn(struct kvm_vcpu *vcpu, struct kvm_timer *ktimer)
* case anyway.
*/
if (ktimer->reinject || !atomic_read(&ktimer->pending)) {
+ atomic_inc(&ktimer->pending);
/* FIXME: this code should not know anything about vcpus */
- if (!atomic_inc_and_test(&ktimer->pending))
- set_bit(KVM_REQ_PENDING_TIMER, &vcpu->requests);
+ set_bit(KVM_REQ_PENDING_TIMER, &vcpu->requests);
}
if (waitqueue_active(q))
prev parent reply other threads:[~2009-06-09 13:37 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-09 9:28 [PATCH] kvm: x86: Fix racy event propagation in kmv timer Jan Kiszka
2009-06-09 13:37 ` [PATCH v2 1/2] " Jan Kiszka
2009-06-09 13:59 ` Marcelo Tosatti
2009-06-14 11:18 ` Avi Kivity
2009-06-09 13:37 ` Jan Kiszka [this message]
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