[PATCH vhost 0/2] virtio_net: fix for stuck when change ring size with dev down

[PATCH vhost 0/2] virtio_net: fix for stuck when change ring size with dev down

[Xuan Zhuo]

When dev is set to DOWN state, napi has been disabled, if we modify the
ring size at this time, we should not call napi_disable() again, which
will cause stuck.

And all operations are under the protection of rtnl_lock, so there is no
need to consider concurrency issues.

PS.
Hi Michael, I don't know which way is more convenient for you, so I split the
commit into two commits, so you can fixup to my previous commit:

    virtio_net: support tx queue resize
	virtio_net: support rx queue resize

Xuan Zhuo (2):
  virtio_net: fix for stuck when change rx ring size with dev down
  virtio_net: fix for stuck when change tx ring size with dev down

 drivers/net/virtio_net.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

--
2.31.0

[PATCH 1/2] virtio_net: fix for stuck when change rx ring size with dev down

[Xuan Zhuo]

When dev is set to DOWN state, napi has been disabled, if we modify the
ring size at this time, we should not call napi_disable() again, which
will cause stuck.

And all operations are under the protection of rtnl_lock, so there is no
need to consider concurrency issues.

Reported-by: Kangjie Xu <kangjie.xu@linux.alibaba.com>
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 drivers/net/virtio_net.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 816c613c22f7..17687eb3f0bd 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1892,11 +1892,13 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
 static int virtnet_rx_resize(struct virtnet_info *vi,
 			     struct receive_queue *rq, u32 ring_num)
 {
+	bool running = netif_running(vi->dev);
 	int err, qindex;
 
 	qindex = rq - vi->rq;
 
-	napi_disable(&rq->napi);
+	if (running)
+		napi_disable(&rq->napi);
 
 	err = virtqueue_resize(rq->vq, ring_num, virtnet_rq_free_unused_buf);
 	if (err)
@@ -1905,7 +1907,8 @@ static int virtnet_rx_resize(struct virtnet_info *vi,
 	if (!try_fill_recv(vi, rq, GFP_KERNEL))
 		schedule_delayed_work(&vi->refill, 0);
 
-	virtnet_napi_enable(rq->vq, &rq->napi);
+	if (running)
+		virtnet_napi_enable(rq->vq, &rq->napi);
 	return err;
 }
 
-- 
2.31.0

[PATCH 2/2] virtio_net: fix for stuck when change tx ring size with dev down

[Xuan Zhuo]

When dev is set to DOWN state, napi has been disabled, if we modify the
ring size at this time, we should not call napi_disable() again, which
will cause stuck.

And all operations are under the protection of rtnl_lock, so there is no
need to consider concurrency issues.

Reported-by: Kangjie Xu <kangjie.xu@linux.alibaba.com>
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 drivers/net/virtio_net.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 17687eb3f0bd..d9c434b00e9b 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1915,12 +1915,14 @@ static int virtnet_rx_resize(struct virtnet_info *vi,
 static int virtnet_tx_resize(struct virtnet_info *vi,
 			     struct send_queue *sq, u32 ring_num)
 {
+	bool running = netif_running(vi->dev);
 	struct netdev_queue *txq;
 	int err, qindex;
 
 	qindex = sq - vi->sq;
 
-	virtnet_napi_tx_disable(&sq->napi);
+	if (running)
+		virtnet_napi_tx_disable(&sq->napi);
 
 	txq = netdev_get_tx_queue(vi->dev, qindex);
 
@@ -1946,7 +1948,8 @@ static int virtnet_tx_resize(struct virtnet_info *vi,
 	netif_tx_wake_queue(txq);
 	__netif_tx_unlock_bh(txq);
 
-	virtnet_napi_tx_enable(vi, sq->vq, &sq->napi);
+	if (running)
+		virtnet_napi_tx_enable(vi, sq->vq, &sq->napi);
 	return err;
 }
 
-- 
2.31.0

Re: [PATCH vhost 0/2] virtio_net: fix for stuck when change ring size with dev down

[Michael S. Tsirkin]

On Thu, Aug 11, 2022 at 04:02:56PM +0800, Xuan Zhuo wrote:
> When dev is set to DOWN state, napi has been disabled, if we modify the
> ring size at this time, we should not call napi_disable() again, which
> will cause stuck.
> 
> And all operations are under the protection of rtnl_lock, so there is no
> need to consider concurrency issues.
> 
> PS.
> Hi Michael, I don't know which way is more convenient for you, so I split the
> commit into two commits, so you can fixup to my previous commit:
> 
>     virtio_net: support tx queue resize
> 	virtio_net: support rx queue resize
> 
> Xuan Zhuo (2):
>   virtio_net: fix for stuck when change rx ring size with dev down
>   virtio_net: fix for stuck when change tx ring size with dev down
> 
>  drivers/net/virtio_net.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)


Which patches does this fix?
Maybe I should squash.

> --
> 2.31.0

Re: [PATCH vhost 0/2] virtio_net: fix for stuck when change ring size with dev down

[Xuan Zhuo]

On Thu, 11 Aug 2022 04:11:22 -0400, "Michael S. Tsirkin" <mst@redhat.com> wrote:
> On Thu, Aug 11, 2022 at 04:02:56PM +0800, Xuan Zhuo wrote:
> > When dev is set to DOWN state, napi has been disabled, if we modify the
> > ring size at this time, we should not call napi_disable() again, which
> > will cause stuck.
> >
> > And all operations are under the protection of rtnl_lock, so there is no
> > need to consider concurrency issues.
> >
> > PS.
> > Hi Michael, I don't know which way is more convenient for you, so I split the
> > commit into two commits, so you can fixup to my previous commit:
> >
> >     virtio_net: support tx queue resize
> > 	virtio_net: support rx queue resize
> >
> > Xuan Zhuo (2):
> >   virtio_net: fix for stuck when change rx ring size with dev down
> >   virtio_net: fix for stuck when change tx ring size with dev down
> >
> >  drivers/net/virtio_net.c | 14 ++++++++++----
> >  1 file changed, 10 insertions(+), 4 deletions(-)
>
>
> Which patches does this fix?
> Maybe I should squash.

These two:
     virtio_net: support tx queue resize
     virtio_net: support rx queue resize

Thanks.


>
> > --
> > 2.31.0
>

Re: [PATCH vhost 0/2] virtio_net: fix for stuck when change ring size with dev down

[Jakub Kicinski]

On Thu, 11 Aug 2022 04:11:22 -0400 Michael S. Tsirkin wrote:
> Which patches does this fix?
> Maybe I should squash.

Side question to make sure I understand the terminology - this 
is *not* a vhost patch, right? vhost is the host side of virtio?
Is the work going via the vhost tree because of some dependencies?

Re: [PATCH vhost 0/2] virtio_net: fix for stuck when change ring size with dev down

[Xuan Zhuo]

On Thu, 11 Aug 2022 10:37:30 -0700, Jakub Kicinski <kuba@kernel.org> wrote:
> On Thu, 11 Aug 2022 04:11:22 -0400 Michael S. Tsirkin wrote:
> > Which patches does this fix?
> > Maybe I should squash.
>
> Side question to make sure I understand the terminology - this
> is *not* a vhost patch, right? vhost is the host side of virtio?
> Is the work going via the vhost tree because of some dependencies?


Yes, the commits fixed by this patch are currently in Michael's vhost branch.

  https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git/log/?h=linux-next

So I mean that by "vhost" here, not into the net/net-next branch. Or should I use
a more accurate term next time?

Thanks.

Re: [PATCH vhost 0/2] virtio_net: fix for stuck when change ring size with dev down

[Jakub Kicinski]

On Fri, 12 Aug 2022 09:30:38 +0800 Xuan Zhuo wrote:
> Yes, the commits fixed by this patch are currently in Michael's vhost branch.
> 
>   https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git/log/?h=linux-next
> 
> So I mean that by "vhost" here, not into the net/net-next branch. Or should I use
> a more accurate term next time?

The tagging seems good, perhaps add a note to the commit message next
time. Maybe a lore link to the series you are fixing up?
The virtio_net.c patches usually go via netdev AFAIU and we're lacking
the vhost context.