From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751482AbaCZG7N (ORCPT ); Wed, 26 Mar 2014 02:59:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44116 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751027AbaCZG7L (ORCPT ); Wed, 26 Mar 2014 02:59:11 -0400 Date: Wed, 26 Mar 2014 08:59:14 +0200 From: "Michael S. Tsirkin" To: Jason Wang Cc: rusty@rustcorp.com.au, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Heinz Graalfs Subject: Re: [PATCH net] virtio-net: correct error handling of virtqueue_kick() Message-ID: <20140326065914.GA13127@redhat.com> References: <1395810180-35169-1-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1395810180-35169-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 26, 2014 at 01:03:00PM +0800, Jason Wang wrote: > Current error handling of virtqueue_kick() was wrong in two places: > - The skb were freed immediately when virtqueue_kick() fail during > xmit. This may lead double free since the skb was not detached from > the virtqueue. > - try_fill_recv() returns false when virtqueue_kick() fail. This will > lead unnecessary rescheduling of refill work. > > Actually, it's safe to just ignore the kick failure in those two > places. So this patch fixes this by partially revert commit > 67975901183799af8e93ec60e322f9e2a1940b9b. > > Fixes 67975901183799af8e93ec60e322f9e2a1940b9b > (virtio_net: verify if virtqueue_kick() succeeded). > > Cc: Heinz Graalfs > Cc: Rusty Russell > Cc: Michael S. Tsirkin > Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin > --- > drivers/net/virtio_net.c | 6 +++--- > 1 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 5632a99..841b608 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -671,8 +671,7 @@ static bool try_fill_recv(struct receive_queue *rq, gfp_t gfp) > if (err) > break; > } while (rq->vq->num_free); > - if (unlikely(!virtqueue_kick(rq->vq))) > - return false; > + virtqueue_kick(rq->vq); > return !oom; > } > > @@ -877,7 +876,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) > err = xmit_skb(sq, skb); > > /* This should not happen! */ > - if (unlikely(err) || unlikely(!virtqueue_kick(sq->vq))) { > + if (unlikely(err)) { > dev->stats.tx_fifo_errors++; > if (net_ratelimit()) > dev_warn(&dev->dev, > @@ -886,6 +885,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) > kfree_skb(skb); > return NETDEV_TX_OK; > } > + virtqueue_kick(sq->vq); > > /* Don't wait up for transmitted skbs to be freed. */ > skb_orphan(skb); > -- > 1.7.1