virtio_net: Add schedule check to napi_enable call

commit 3e9d08ec0a68f6faf718d5a7e050fe5ca0ba004f upstream.

Under harsh testing conditions, including low memory, the guest would
stop receiving packets. With this patch applied we no longer see any
problems in the driver while performing these tests for extended periods
of time.

Make sure napi is scheduled subsequent to each napi_enable.

Signed-off-by: Bruce Rogers <brogers@novell.com>
Signed-off-by: Olaf Kirch <okir@suse.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
[bwh: Adjust for 2.6.32]
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index bb6b67f6b0cc731df707cbfc06006a2c8c39b198..1cf8da8f361a5362038f68aafa3e7ef3d3689fc5 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -446,6 +446,20 @@ static void skb_recv_done(struct virtqueue *rvq)
        }
 }
 
+static void virtnet_napi_enable(struct virtnet_info *vi)
+{
+       napi_enable(&vi->napi);
+
+       /* If all buffers were filled by other side before we napi_enabled, we
+        * won't get another interrupt, so process any outstanding packets
+        * now.  virtnet_poll wants re-enable the queue, so we disable here.
+        * We synchronize against interrupts via NAPI_STATE_SCHED */
+       if (napi_schedule_prep(&vi->napi)) {
+               virtqueue_disable_cb(vi->rvq);
+               __napi_schedule(&vi->napi);
+       }
+}
+
 static void refill_work(struct work_struct *work)
 {
        struct virtnet_info *vi;
@@ -454,7 +468,7 @@ static void refill_work(struct work_struct *work)
        vi = container_of(work, struct virtnet_info, refill.work);
        napi_disable(&vi->napi);
        still_empty = !try_fill_recv(vi, GFP_KERNEL);
-       napi_enable(&vi->napi);
+       virtnet_napi_enable(vi);
 
        /* In theory, this can happen: if we don't get any buffers in
         * we will *never* try to fill again. */
@@ -638,16 +652,7 @@ static int virtnet_open(struct net_device *dev)
 {
        struct virtnet_info *vi = netdev_priv(dev);
 
-       napi_enable(&vi->napi);
-
-       /* If all buffers were filled by other side before we napi_enabled, we
-        * won't get another interrupt, so process any outstanding packets
-        * now.  virtnet_poll wants re-enable the queue, so we disable here.
-        * We synchronize against interrupts via NAPI_STATE_SCHED */
-       if (napi_schedule_prep(&vi->napi)) {
-               virtqueue_disable_cb(vi->rvq);
-               __napi_schedule(&vi->napi);
-       }
+       virtnet_napi_enable(vi);
        return 0;
 }