[ECOS] TCP driver eth_drv.c -- bug fix

["Jon Hartley" <jdh at cea dot com dot au>]

Hi,

 Correct me if i'm wrong but it appears that a freed mbuf pointer (top) is
passed to ether_input() in eth_drv_recv() when MGET fails in the while loop.
I suspect this was causing bad things to happen to our mbufs, resulting in
mbuf loss and crash etc (depending on what ether_input does with it).

static void
eth_drv_recv(struct eth_drv_sc *sc, int total_len)
    ...
    while (total_len > 0) {
        if (top) {
            MGET(m, M_DONTWAIT, MT_DATA);
            if (m == 0) {
                m_freem(top);
#ifdef CYGPKG_IO_ETH_DRIVERS_WARN_NO_MBUFS
                diag_printf("out of MBUFs [2]");
#endif
                sg_list[sg_len].buf = (CYG_ADDRESS)0;
                sg_list[sg_len].len = 0;
                sg_len = 1;
-->             top = 0; //jdh
                break;
            }
            mlen = MLEN;
        }

	...

More mbufs fixes to follow (in if_quicc.c).

Cheers,
   Jon.