From: Stephen Hemminger <step...@networkplumber.org>
Date: Wed, 6 Sep 2017 13:53:05 -0700
> When a virtual device is added dynamically (via host console), then
> the vmbus sends an offer message for the primary channel. The processing
> of this message for networking causes the network device to then
> initialize the sub channels.
>
> The problem is that setting up the sub channels needs to wait until
> the subsequent subchannel offers have been processed. These offers
> come in on the same ring buffer and work queue as where the primary
> offer is being processed; leading to a deadlock.
>
> This did not happen in older kernels, because the sub channel waiting
> logic was broken (it wasn't really waiting).
>
> The solution is to do the sub channel setup in its own work queue
> context that is scheduled by the primary channel setup; and then
> happens later.
>
> Fixes: 732e49850c5e ("netvsc: fix race on sub channel creation")
> Reported-by: Dexuan Cui <de...@microsoft.com>
> Signed-off-by: Stephen Hemminger <sthem...@microsoft.com>
> ---
> v2 - fix module removal race with new work queue
Applied.
