On Tue, 19 Aug 2003 15:04:48 +0200
"Angelo Dell'Aera" <buffer@antifork.org> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
>
> I was looking at the source of one of the NIC drivers which triggers a
> kernel panic when removed while generating traffic and maybe I
> realized what should be the cause of it. I'm referring to 3c509
> driver. Taking a look at the cleanup routine
>
>
> static void __exit el3_cleanup_module(void)
> {
> struct net_device *next_dev;
>
> while (el3_root_dev) {
> struct el3_private *lp = (struct el3_private *)el3_root_dev->priv;
>
> next_dev = lp->next_dev;
> el3_common_remove (el3_root_dev);
> el3_root_dev = next_dev;
> }
> [..]
>
>
> static void el3_common_remove (struct net_device *dev)
> {
> struct el3_private *lp = dev->priv;
>
> (void) lp; /* Keep gcc quiet... */
> #ifdef CONFIG_PM
> if (lp->pmdev)
> pm_unregister(lp->pmdev);
> #endif
> #if defined(__ISAPNP__) && !defined(CONFIG_X86_PC9800)
> if (lp->type == EL3_PNP)
> pnp_device_detach(to_pnp_dev(lp->dev));
> #endif
>
> unregister_netdev (dev);
> release_region(dev->base_addr, EL3_IO_EXTENT);
> kfree (dev);
> }
>
>
> If a user doesn't shut down the interface before removing the module,
> it's easy to realize that some problems could occur. First of all, I
> think that before calling el3_common_remove() in the cleanup routine,
> it could be safer to call a netif_stop_queue() on the net device to be
> removed. Then, after the while loop, I think we should take care of
> releasing the IRQ.
>
If user hasn't shutdown the device then unregister_netdev does
the shutdown itself by calling dev_close -> el3_close -> el3_down.
The problem may be that the el3_down routine needs to wait till the
receiver has completed shutting down, or check for packets in flight
on transmit. Shutting off receiver and transmitter are chip dependant
and there may be issues doing it when chip is busy.
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