From 9541896b8e5bf0d83f0f6e92a9e9298dd0e33d5f Mon Sep 17 00:00:00 2001
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Wed, 13 Jan 2010 18:58:09 +0200
Subject: [PATCH] --- yaml --- r: 179955 b: refs/heads/master c:
 f1d1c309f35e9b0fb961cffd70fbd04f450ec47c h: refs/heads/master i:   179953:
 0cecdaf7b6ca6f9c7fe00bbc8757b366a628bcbd   179951:
 c6da42976eb0afb0dd25d21739ec30805c91729a v: v3

---
 [refs]                   |  2 +-
 trunk/virt/kvm/eventfd.c | 15 +++++++++++++--
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/[refs] b/[refs]
index 2708dbcd656a..7171675added 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 82b7005f0e72d8d1a8226e4c192cbb0850d10b3f
+refs/heads/master: f1d1c309f35e9b0fb961cffd70fbd04f450ec47c
diff --git a/trunk/virt/kvm/eventfd.c b/trunk/virt/kvm/eventfd.c
index 30f70fd511c4..62e4cd947a90 100644
--- a/trunk/virt/kvm/eventfd.c
+++ b/trunk/virt/kvm/eventfd.c
@@ -166,7 +166,7 @@ irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
 static int
 kvm_irqfd_assign(struct kvm *kvm, int fd, int gsi)
 {
-	struct _irqfd *irqfd;
+	struct _irqfd *irqfd, *tmp;
 	struct file *file = NULL;
 	struct eventfd_ctx *eventfd = NULL;
 	int ret;
@@ -203,9 +203,20 @@ kvm_irqfd_assign(struct kvm *kvm, int fd, int gsi)
 	init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
 	init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
 
+	spin_lock_irq(&kvm->irqfds.lock);
+
+	ret = 0;
+	list_for_each_entry(tmp, &kvm->irqfds.items, list) {
+		if (irqfd->eventfd != tmp->eventfd)
+			continue;
+		/* This fd is used for another irq already. */
+		ret = -EBUSY;
+		spin_unlock_irq(&kvm->irqfds.lock);
+		goto fail;
+	}
+
 	events = file->f_op->poll(file, &irqfd->pt);
 
-	spin_lock_irq(&kvm->irqfds.lock);
 	list_add_tail(&irqfd->list, &kvm->irqfds.items);
 	spin_unlock_irq(&kvm->irqfds.lock);