On 11/03/2016 05:09 PM, Yuanhan Liu wrote:
> This reverts commit 9a0615af7746 ("virtio: fix restart"); conflict is
> manually addressed.
>
> Kyle reported an issue with above commit
>
> qemu-kvm: Guest moved used index from 5 to 1
>
> with following steps,
>
> 1) Start my virtio interfaces
> 2) Send some traffic into/out of the interfaces
> 3) Stop the interfaces
> 4) Start the interfaces
> 5) Send some more traffic
>
> And here are some quotes from Kyle's analysis,
>
> Prior to the patch, if an interface were stopped then started, without
> restarting the application, the queues would be left as-is, because
> hw->started would be set to 1. Now, calling stop sets hw->started to 0,
> which means the next call to start will "touch the queues". This is the
> unintended side-effect that causes the problem.
>
> Fixes: 9a0615af7746 ("virtio: fix restart")
>
> Cc: Jianfeng Tan <jianfeng.tan at intel.com>
> Cc: <stable at dpdk.org>
> Reported-by: Kyle Larose <klarose at sandvine.com>
> Signed-off-by: Yuanhan Liu <yuanhan.liu at linux.intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>
Thanks,
Maxime
