linux-kernel - [PATCH] virtio-rng: Remove false BUG for spurious callbacks

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Message-Id: <200904231642.59939.rusty@rustcorp.com.au>
Date:	Thu, 23 Apr 2009 16:42:59 +0930
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org,
	Christian Borntraeger <borntraeger@...ibm.com>,
	stable@...nel.org
Subject: [PATCH] virtio-rng: Remove false BUG for spurious callbacks

From: Christian Borntraeger <borntraeger@...ibm.com>

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@...ibm.com>
---
 drivers/char/hw_random/virtio-rng.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-2.6/drivers/char/hw_random/virtio-rng.c
===================================================================
--- linux-2.6.orig/drivers/char/hw_random/virtio-rng.c
+++ linux-2.6/drivers/char/hw_random/virtio-rng.c
@@ -37,9 +37,9 @@ static void random_recv_done(struct virt
 {
 	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);
--
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