From: Christian Borntraeger <borntraeger@de.ibm.com>
Date: Fri, 24 Apr 2009 22:35:03 +0000 (+0000)
Subject: virtio-rng: Remove false BUG for spurious callbacks
X-Git-Tag: v2.6.29.3~46
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=87b59eac0914ab407df57fe23d880dccd9a9436d;p=thirdparty%2Fkernel%2Fstable.git

virtio-rng: Remove false BUG for spurious callbacks

upstream commit: e5b89542ea18020961882228c26db3ba87f6e608

The virtio-rng drivers checks for spurious callbacks. Since
callbacks can be implemented via shared interrupts (e.g. PCI) this
could lead to guest kernel oopses with lots of virtio devices.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---

diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
index d0e563e4fc399..86e83f883139e 100644
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -37,9 +37,9 @@ static void random_recv_done(struct virtqueue *vq)
 {
 	int len;
 
-	/* We never get spurious callbacks. */
+	/* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */
 	if (!vq->vq_ops->get_buf(vq, &len))
-		BUG();
+		return;
 
 	data_left = len / sizeof(random_data[0]);
 	complete(&have_data);