On Thu, Feb 10, 2011 at 12:32:50PM +1030, Rusty Russell wrote:
> From: "Bruce Rogers" <brogers@xxxxxxxxxx>
>
> 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@xxxxxxxxxx>
> Signed-off-by: Olaf Kirch <okir@xxxxxxx>
> Cc: stable@xxxxxxxxxx
> Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Rusty, so this is 2.6.38 material - you'll send this to Linus? Or DaveM?
> ---
> drivers/net/virtio_net.c | 27 ++++++++++++++++-----------
> 1 file changed, 16 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -446,6 +446,20 @@ static void skb_recv_done(struct virtque
> }
> }
>
> +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_stru
> 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_devic
> {
> 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;
> }
>
> --
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