Re: [PATCH] net: virtio: clear reserved vring properly at setup time

[Yuanhan Liu <yuanhan.liu@linux.intel.com>]

On Mon, Jul 18, 2016 at 07:09:24PM +0200, Maxime Coquelin wrote:
> After vring reservation, only the first bytes of the vring were
> cleared.
> 
> This patch fixes this to clear the real size fo the vring.
> 
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
> 
> Note: I found this bug while doing some code review,

Nice catch!

> it is not a fix for
> a problem I encountered.

Yes, there should be no problem: vring memory is completely zero-ed
at port start stage by virtio_dev_vring_start().

> ---
>  drivers/net/virtio/virtio_ethdev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
> index 850e3ba..336b3fc 100644
> --- a/drivers/net/virtio/virtio_ethdev.c
> +++ b/drivers/net/virtio/virtio_ethdev.c
> @@ -387,7 +387,7 @@ int virtio_dev_queue_setup(struct rte_eth_dev *dev,
>  		}
>  	}
>  
> -	memset(mz->addr, 0, sizeof(mz->len));
> +	memset(mz->addr, 0, mz->len);

Actually, I think we could simply drop the memset here. It's redundant,
as stated.

And to Thomas, I don't find a good reason to have this in 16.07. Let's
delay the apply to v16.11.

	--yliu

>  	vq->vq_ring_mem = mz->phys_addr;
>  	vq->vq_ring_virt_mem = mz->addr;
> -- 
> 2.7.4