Suspicious sequence of code in ibm_ocp_enet.c

Hi!

I found a strange sequence of code in ppc405_enet_open (devel_2_4 & devel_2_5).

init_rings is called _AFTER_ enabling MAL tx and rx channels:

static int
ppc405_enet_open(struct net_device *dev)
{

        ... some code skipped ...

         /* enable all MAL transmit and receive channels */
         enable_mal_chan(fep);

         /* set transmit and receive enable */
         out_be32(&emacp->em0mr0, EMAC_M0_TXE | EMAC_M0_RXE);

         init_rings(dev);

        netif_start_queue(dev);
         printk(KERN_NOTICE "%s: IBM EMAC: open completed\n\n", dev->name);

         return 0;
}

I suspect that this can cause some trouble during opening the device if a
packet arrives just after enabling rx channel but before init_rings is
executed. Frankly, I'm pretty sure that this causes infrequent crashes on
our custom 405GP board.

I'd move call to init_rings(dev) just before enable_mal_chan(fep);

Any ideas, suggestions ?

Thanks,


  Eugene Surovegin <mailto:ebs@innocent.com>


** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

On Tue, Nov 19, 2002 at 11:50:43PM -0800, Eugene Surovegin wrote:

Hi!

I found a strange sequence of code in ppc405_enet_open (devel_2_4 &
devel_2_5).

init_rings is called _AFTER_ enabling MAL tx and rx channels:

static int
ppc405_enet_open(struct net_device *dev)
{

       ... some code skipped ...

        /* enable all MAL transmit and receive channels */
        enable_mal_chan(fep);

        /* set transmit and receive enable */
        out_be32(&emacp->em0mr0, EMAC_M0_TXE | EMAC_M0_RXE);

        init_rings(dev);

       netif_start_queue(dev);
        printk(KERN_NOTICE "%s: IBM EMAC: open completed\n\n", dev->name);

        return 0;
}

I suspect that this can cause some trouble during opening the device if a
packet arrives just after enabling rx channel but before init_rings is
executed. Frankly, I'm pretty sure that this causes infrequent crashes on
our custom 405GP board.

I'd move call to init_rings(dev) just before enable_mal_chan(fep);

Any ideas, suggestions ?

It certainly looks dodgy.  Try changing it and see what happens.  Then
send a patch :-)

--
David Gibson			| For every complex problem there is a
david@gibson.dropbear.id.au	| solution which is simple, neat and
				| wrong.
http://www.ozlabs.org/people/dgibson

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/