>       for (i = 0; i < NUM_TX_BUFF; ++i) {
        > -             if (dev->tx_skb[i]) {
        > +             if (dev->tx_skb[i] &&
        dev->tx_desc[i].data_ptr) {
        
        
        Why changing the test above ?

   The reason for changing this condition is ,  In any of the case if
the dev->tx_skb is not containing valid address, Then while clearing
it you may be resulted in "address voilations". This additional
condition ensures that we are clearing the valid skbs.
Further this condition is not in general data flow, So this additional
condition should not have any impact on performance.

Do you see -any- case where tx_skb[i] and dev->tx_desc[i].data_ptr would
be out of sync ? If that's the case, shouldn't we cleanup instead of
leaving some kind of stale entry in the ring ?

In addition, in pure theory, data_ptr == 0 is a valid DMA address :-) So
I think that part of the patch shouldn't be there.

        
        >                       dev_kfree_skb(dev->tx_skb[i]);
        >                       dev->tx_skb[i] = NULL;
        >                       if (dev->tx_desc[i].ctrl &
        MAL_TX_CTRL_READY)
        > @@ -2719,6 +2719,10 @@ static int __devinit
        emac_probe(struct of_device *ofdev,
        >       /* Clean rings */
        >       memset(dev->tx_desc, 0, NUM_TX_BUFF * sizeof(struct
        mal_descriptor));
        >       memset(dev->rx_desc, 0, NUM_RX_BUFF * sizeof(struct
        mal_descriptor));
        > +     for (i = 0; i <= NUM_TX_BUFF; i++)
        > +             dev->tx_skb[i] = NULL;
        > +     for (i = 0; i <= NUM_RX_BUFF; i++)
        > +             dev->rx_skb[i] = NULL;
        
        
        Why not use memset here too ?
    Yes, It was valid to use memset here. I can send the modified
patch for it. 

Please do, thanks.

Cheers,
Ben.