Re: [Xen-devel] bogus wrap check in xen-netback

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Apr 25, 2018 at 09:39:24AM +0200, Olaf Hering wrote:
> Am Wed, 25 Apr 2018 09:28:38 +0200
> schrieb Juergen Gross <jgross@xxxxxxxx>:
> 
> > Why? (u16)0 - (u16)65400 == 136
> 
> My helloworld.c shows that ushort gets promoted to uint, unless it is done 
> like that:
> 
> -               if (queue->tx.sring->req_prod - queue->tx.req_cons >
> -                   XEN_NETIF_TX_RING_SIZE) {
> +               idx = queue->tx.sring->req_prod - queue->tx.req_cons; 
> +               if ( idx > XEN_NETIF_TX_RING_SIZE) {

Do you have the full diff of your changes? I don't follow why integer
conversion works differently if you write the code like this. As far as
I can tell the type of LHS didn't change.

Wei.

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