[PATCH 1/9] kvm/eventfd: avoid loop inside irqfd_update()

Denis V. Lunev
Fri, 16 Oct 2015 07:07:45 -0000

The loop(for) inside irqfd_update() is unnecessary
because any other value for irq_entry.type will just trigger
schedule_work(&irqfd->inject).

Signed-off-by: Andrey Smetanin <asmetanin at virtuozzo.com>
Reviewed-by: Roman Kagan <rkagan at virtuozzo.com>
Signed-off-by: Denis V. Lunev <den at openvz.org>
CC: Vitaly Kuznetsov <vkuznets at redhat.com>
CC: "K. Y. Srinivasan" <kys at microsoft.com>
CC: Gleb Natapov <gleb at kernel.org>
CC: Paolo Bonzini <pbonzini at redhat.com>
---
 virt/kvm/eventfd.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index b637965..518421e 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -238,20 +238,17 @@ static void irqfd_update(struct kvm *kvm, struct
kvm_kernel_irqfd *irqfd)
 {
 	struct kvm_kernel_irq_routing_entry *e;
 	struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
-	int i, n_entries;
+	int n_entries;

 	n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);

 	write_seqcount_begin(&irqfd->irq_entry_sc);

-	irqfd->irq_entry.type = 0;
-
 	e = entries;
-	for (i = 0; i < n_entries; ++i, ++e) {
-		/* Only fast-path MSI. */
-		if (e->type == KVM_IRQ_ROUTING_MSI)
-			irqfd->irq_entry = *e;
-	}
+	if (n_entries == 1)
+		irqfd->irq_entry = *e;
+	else
+		irqfd->irq_entry.type = 0;

 	write_seqcount_end(&irqfd->irq_entry_sc);
 }
--
2.1.4