Re: [PATCH net] virtio-net: fix the race between channels settingand refill

[David Miller]

From: Jason Wang <jasowang@xxxxxxxxxx>
Date: Wed,  3 Jul 2013 20:15:52 +0800

> Commit 55257d72bd1c51f25106350f4983ec19f62ed1fa (virtio-net: fill only rx queues
> which are being used) tries to refill on demand when changing the number of
> channels by call try_refill_recv() directly, this may race:
> 
> - the refill work who may do the refill in the same time
> - the try_refill_recv() called in bh since napi was not disabled
> 
> Which may led guest complain during setting channels:
> 
> virtio_net virtio0: input.1:id 0 is not a head!
> 
> Solve this issue by scheduling a refill work which can guarantee the
> serialization of refill.
> 
> Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>

Michael, please review.

Thanks.
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