Messages in this thread | | | Subject | Re: [PATCH] virtio_net: enable tx after resuming from suspend | From | ake <> | Date | Fri, 12 Oct 2018 18:18:01 +0900 |
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On 2018年10月12日 17:23, Jason Wang wrote: > > > 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.
If you mean the interface state before I hit the suspend button, the answer is yes. The interface is up before I suspend the guest machine.
Note that my current QEMU version is QEMU emulator version 2.5.0 (Debian 1:2.5+dfsg-5ubuntu10.32).
I will try with net-next.git and qemu master later and see if I can reproduce the issue.
>> >>>> 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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