Re: [PATCH v3 06/10] net/macb: clean up ring buffer logic

[Nicolas Ferre]

On 10/30/2012 07:22 PM, Håvard Skinnemoen :
> On Tue, Oct 30, 2012 at 4:12 AM, David Laight <David.Laight@xxxxxxxxxx> wrote:
>>> Instead of masking head and tail every time we increment them, just let them
>>> wrap through UINT_MAX and mask them when subscripting. Add simple accessor
>>> functions to do the subscripting properly to minimize the chances of messing
>>> this up.
>> ...
>>> +static unsigned int macb_tx_ring_avail(struct macb *bp)
>>> +{
>>> +     return TX_RING_SIZE - (bp->tx_head - bp->tx_tail);
>>> +}
>>
>> That one doesn't look quite right to me.
>> Surely it should be masking with 'TX_RING_SIZE - 1'
> 
> Why is that? head and tail can never be more than TX_RING_SIZE apart,
> so it shouldn't make any difference.

Absolutely.

Best regards,
-- 
Nicolas Ferre
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