Messages in this thread | | | Subject | Re: [PATCH] virtio_net: enable tx after resuming from suspend | From | Jason Wang <> | Date | Fri, 12 Oct 2018 16:23:48 +0800 |
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On 2018年10月12日 12:30, ake wrote: > > On 2018年10月11日 22:06, Jason Wang wrote: >> >> On 2018年10月11日 18:22, ake wrote: >>> On 2018年10月11日 18:44, Jason Wang wrote: >>>> On 2018年10月11日 15:51, Ake Koomsin wrote: >>>>> commit 713a98d90c5e ("virtio-net: serialize tx routine during reset") >>>>> disabled the virtio tx before going to suspend to avoid a use after >>>>> free. >>>>> However, after resuming, it causes the virtio_net device to lose its >>>>> network connectivity. >>>>> >>>>> To solve the issue, we need to enable tx after resuming. >>>>> >>>>> Fixes commit 713a98d90c5e ("virtio-net: serialize tx routine during >>>>> reset") >>>>> Signed-off-by: Ake Koomsin <ake@igel.co.jp> >>>>> --- >>>>> drivers/net/virtio_net.c | 1 + >>>>> 1 file changed, 1 insertion(+) >>>>> >>>>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >>>>> index dab504ec5e50..3453d80f5f81 100644 >>>>> --- a/drivers/net/virtio_net.c >>>>> +++ b/drivers/net/virtio_net.c >>>>> @@ -2256,6 +2256,7 @@ static int virtnet_restore_up(struct >>>>> virtio_device *vdev) >>>>> } >>>>> netif_device_attach(vi->dev); >>>>> + netif_start_queue(vi->dev); >>>> I believe this is duplicated with netif_tx_wake_all_queues() in >>>> netif_device_attach() above? >>> Thank you for your review. >>> >>> If both netif_tx_wake_all_queues() and netif_start_queue() result in >>> clearing __QUEUE_STATE_DRV_XOFF, then is it possible that some >>> conditions in netif_device_attach() is not satisfied? >> Yes, maybe. One case I can see now is when the device is down, in this >> case netif_device_attach() won't try to wakeup the queue. >> >>> Without >>> netif_start_queue(), the virtio_net device does not resume properly >>> after waking up. >> How do you trigger the issue? Just do suspend/resume? > Yes, simply suspend and resume. > > Here is how I trigger the issue: > > 1) Start the Virtual Machine Manager GUI program. > 2) Create a guest Linux OS. Make sure that the guest OS kernel is > >= 4.12. Make sure that it uses virtio_net as its network device. > In addition, make sure that the video adapter is VGA. Otherwise, > waking up with the virtual power button does not work. > 3) After installing the guest OS, log in, and test the network > connectivity by ping the host machine. > 4) Suspend. After this, the screen is blank. > 5) Resume by hitting the virtual power button. The login screen > appears again. > 6) Log in again. The guest loses its network connection. > > In my test: > Guest: Ubuntu 16.04/18.04 with kernel 4.15.0-36-generic > Host: Ubuntu 16.04 with kernel 4.15.0-36-generic/4.4.0-137-generic
I can not reproduce this issue if virtio-net interface is up in guest before the suspend. I'm using net-next.git and qemu master. But I do reproduce when virtio-net interface is down in guest before suspend, after resume, even if I make it up, the network is still lost.
I think the interface is up in your case, but please confirm this.
> >>> Is it better to report this as a bug first? >> Nope, you're very welcome to post patch directly. >> >>> If I am to do more >>> investigation, what areas should I look into? >> As you've figured out, you can start with why netif_tx_wake_all_queues() >> were not executed? >> >> (Btw, does the issue disappear if you move netif_tx_disable() under the >> check of netif_running() in virtnet_freeze_down()?) > The issue disappears if I move netif_tx_disable() under the check of > netif_running() in virtnet_freeze_down(). Moving netif_tx_disable() > is probably better as its logic is consistent with > netif_device_attach() implementation. If you are OK with this idea, > I will submit another patch.
I think the it helps for the case when interface is down before suspend. But it's still unclear why it help even if the interface is up (netif_running() is true).
Please submit a patch but we should figure out why it help for a up interface as well.
Thanks
> >> Thanks >> >>> Best Regards >>> Ake Koomsin >>> > Best Regards
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