Messages in this thread | | | Subject | Re: [PATCH] virtio_net: enable tx after resuming from suspend | From | ake <> | Date | Tue, 16 Oct 2018 19:15:28 +0900 |
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On 2018年10月16日 17:53, Jason Wang wrote: > > On 2018/10/15 下午6:08, ake wrote: >> >> On 2018年10月12日 18:18, ake wrote: >>> >>> 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. >> Update. I tried with net-next and qemu master. Interestingly, the result >> is different from yours. The network is lost even if the virtio_net >> interface is up before suspending. >> >> Host: Ubuntu 16.04 with net-next kernel (default configuration) >> Guest: Ubuntu 18.04 with net-next kernel (default configuration) >> Qemu: master >> Qemu command: >> qemu-system-x86_64 -cpu host -m 2048 -enable-kvm \ >> -bios /usr/share/OVMF/OVMF_CODE.fd \ >> -drive file=/var/lib/libvirt/images/virtio_test.qcow2,if=virtio \ >> -netdev user,id=hostnet0 \ >> -device virtio-net-pci,netdev=hostnet0 \ >> -device VGA,id=video0,vgamem_mb=16 \ >> -global PIIX4_PM.disable_s3=1 \ >> -global PIIX4_PM.disable_s4=1 -monitor stdio > > > Interesting, just notice you're using userspace network. To isolate the > issue, can you retry with e.g tap or e1000 to make sure it's not a fault > of slirp or virito-net?
I will try.
> Thanks >
There is another thing that I want to discuss. I notice that netif_device_detach() should result in setting __QUEUE_STATE_DRV_XOFF if the network interface is running. By calling netif_tx_disable() after netif_device_detach(), isn't it redundant in case of the network interface is running? If the goal is to serialize tx routine, would netif_tx_lock() and net_tx_unlock() are more appropriate? Like this:
netif_tx_lock(vi->dev); netif_device_detach(vi->dev); netif_tx_unlock(vi->dev);
Currently, netif_tx_disable() seems to disturb the symmetry of netif_device_detach() and netif_device_attach(). That is the reason why you can reproduce the problem when the interface is down before suspending.
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