From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH v3] virtio_net: avoid using netif_tx_disable() for serializing tx routine Date: Wed, 17 Oct 2018 11:09:20 -0400 Message-ID: <20181017110741-mutt-send-email-mst@kernel.org> References: <276ac5bb-90f7-5fb6-a826-0bb05ecfa069@redhat.com> <20181017104419.13003-1-ake@igel.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jason Wang , "David S. Miller" , virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Ake Koomsin Return-path: Content-Disposition: inline In-Reply-To: <20181017104419.13003-1-ake@igel.co.jp> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Wed, Oct 17, 2018 at 07:44:12PM +0900, Ake Koomsin wrote: > Commit 713a98d90c5e ("virtio-net: serialize tx routine during reset") > introduces netif_tx_disable() after netif_device_detach() in order to > avoid use-after-free of tx queues. However, there are two issues. > > 1) Its operation is redundant with netif_device_detach() in case the > interface is running. > 2) In case of the interface is not running before suspending and > resuming, the tx does not get resumed by netif_device_attach(). > This results in losing network connectivity. > > It is better to use netif_tx_lock_bh()/netif_tx_unlock_bh() instead for > serializing tx routine during reset. This also preserves the symmetry > of netif_device_detach() and netif_device_attach(). > > Fixes commit 713a98d90c5e ("virtio-net: serialize tx routine during reset") > Signed-off-by: Ake Koomsin Acked-by: Michael S. Tsirkin Thanks a lot for debugging! Seems like stable material to me, right? > --- > 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 3f5aa59c37b7..3e2c041d76ac 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -2267,8 +2267,9 @@ static void virtnet_freeze_down(struct virtio_device *vdev) > /* Make sure no work handler is accessing the device */ > flush_work(&vi->config_work); > > + netif_tx_lock_bh(vi->dev); > netif_device_detach(vi->dev); > - netif_tx_disable(vi->dev); > + netif_tx_unlock_bh(vi->dev); > cancel_delayed_work_sync(&vi->refill); > > if (netif_running(vi->dev)) { > @@ -2304,7 +2305,9 @@ static int virtnet_restore_up(struct virtio_device *vdev) > } > } > > + netif_tx_lock_bh(vi->dev); > netif_device_attach(vi->dev); > + netif_tx_unlock_bh(vi->dev); > return err; > } > > -- > 2.19.1