| Message ID | 20181017104419.13003-1-ake@igel.co.jp |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | [v3] virtio_net: avoid using netif_tx_disable() for serializing tx routine | expand |
On 2018/10/17 下午6:44, 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 <ake@igel.co.jp> > --- > 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; > } > Acked-by: Jason Wang <jasowang@redhat.com> Thanks
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 <ake@igel.co.jp> Acked-by: Michael S. Tsirkin <mst@redhat.com> 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
On 2018/10/18 0:09, Michael S. Tsirkin wrote: > 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 <ake@igel.co.jp> > > Acked-by: Michael S. Tsirkin <mst@redhat.com> > > Thanks a lot for debugging! > Seems like stable material to me, right? Yes. With this patch, we can avoid network connectivity lost because of tx not get re-enabled under some situation. Plus, it avoids redundant operation between netif_device_detach() and netif_tx_disable(). I tested the patch on Linux net-next and QEMU master by suspending/ resuming the virtual machine repeatedly. The network looks no problem and has no connectivity lost so far. I tested with both user-mode networking and tap interface. Best Regards >> --- >> 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
From: Ake Koomsin <ake@igel.co.jp> Date: Wed, 17 Oct 2018 19:44:12 +0900 > 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 <ake@igel.co.jp> Applied and queued up for -stable.
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; }
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 <ake@igel.co.jp> --- drivers/net/virtio_net.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)