Messages in this thread | | | Subject | Re: [PATCH] virtio_net: enable tx after resuming from suspend | From | ake <> | Date | Mon, 15 Oct 2018 19:08:06 +0900 |
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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
>>> >>>>> 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. >>
I will think about the proper reason first.
>> Thanks >> >>> >>>> Thanks >>>> >>>>> Best Regards >>>>> Ake Koomsin >>>>> >>> Best Regards >>
Best Regards
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