From: Michael S. Tsirkin <mst@redhat.com>
Date: Wed, 13 Jan 2010 17:12:30 +0000 (+0200)
Subject: KVM: fix spurious interrupt with irqfd
X-Git-Tag: v3.12-rc1~11490^2~3
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=b6a114d27273c37cd0107b0f49af208168498f05;p=kernel%2Fkernel-generic.git

KVM: fix spurious interrupt with irqfd

kvm didn't clear irqfd counter on deassign, as a result we could get a
spurious interrupt when irqfd is assigned back. this leads to poor
performance and, in theory, guest crash.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
---

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 62e4cd9..a9d3fc6 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -72,12 +72,13 @@ static void
 irqfd_shutdown(struct work_struct *work)
 {
 	struct _irqfd *irqfd = container_of(work, struct _irqfd, shutdown);
+	u64 cnt;
 
 	/*
 	 * Synchronize with the wait-queue and unhook ourselves to prevent
 	 * further events.
 	 */
-	remove_wait_queue(irqfd->wqh, &irqfd->wait);
+	eventfd_ctx_remove_wait_queue(irqfd->eventfd, &irqfd->wait, &cnt);
 
 	/*
 	 * We know no new events will be scheduled at this point, so block