On Tue, Nov 15, 2016 at 10:24:12PM -0800, Eric Dumazet wrote:
> From: Eric Dumazet <eduma...@google.com>
>
> It seems many drivers do not respect napi_hash_del() contract.
>
> When napi_hash_del() is used before netif_napi_del(), an RCU grace
> period is needed before freeing NAPI object.
>
> Fixes: 91815639d880 ("virtio-net: rx busy polling support")
> Signed-off-by: Eric Dumazet <eduma...@google.com>
> Cc: Jason Wang <jasow...@redhat.com>
> Cc: Michael S. Tsirkin <m...@redhat.com>
Acked-by: Michael S. Tsirkin <m...@redhat.com>
> ---
> drivers/net/virtio_net.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index fd8b1e62301f..7276d5a95bd0 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1497,6 +1497,11 @@ static void virtnet_free_queues(struct virtnet_info
> *vi)
> netif_napi_del(&vi->rq[i].napi);
> }
>
> + /* We called napi_hash_del() before netif_napi_del(),
> + * we need to respect an RCU grace period before freeing vi->rq
> + */
> + synchronize_net();
> +
> kfree(vi->rq);
> kfree(vi->sq);
> }
>
