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Subject[PATCH 2/4] virtio_net: add a timeout in virtnet_send_command()
Date
if the device control queue is buggy, don't crash the kernel by
waiting for ever the response.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
drivers/net/virtio_net.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 25511a86590e..29b3cc72082d 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1974,6 +1974,7 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
struct scatterlist *sgs[4], hdr, stat;
unsigned out_num = 0, tmp;
int ret;
+ unsigned long timeout;

/* Caller should know better */
BUG_ON(!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ));
@@ -2006,8 +2007,10 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
/* Spin for a response, the kick causes an ioport write, trapping
* into the hypervisor, so the request should be handled immediately.
*/
+ timeout = jiffies + 20 * HZ;
while (!virtqueue_get_buf(vi->cvq, &tmp) &&
- !virtqueue_is_broken(vi->cvq))
+ !virtqueue_is_broken(vi->cvq) &&
+ !time_after(jiffies, timeout))
cpu_relax();

return vi->ctrl->status == VIRTIO_NET_OK;
--
2.39.0
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