Bug#656476: Sundance network driver (D-Link DFE-580TX) timeouts rendering interface unusable

[Eric Dumazet <eric.dumazet@gmail.com>]

Le lundi 30 janvier 2012 à 12:51 +0300, Denis Kirjanov a écrit :
> I'll check this out. After kernel.org was cracked I've missed
> @kernel.org mail account.


At first glance, start_tx() is racy against TX completion.

It does :

        if (np->cur_tx - np->dirty_tx < TX_QUEUE_LEN - 1 &&
            !netif_queue_stopped(dev)) {
                /* do nothing */
        } else {
                netif_stop_queue (dev);
        }

So it can call netif_stop_queue() while TX completion handler did a
cleanup of all queued packets right before.


Note intr_handler() doesnt hold the queue spinlock when it does :

                if (netif_queue_stopped(dev) &&
                        np->cur_tx - np->dirty_tx < TX_QUEUE_LEN - 4) {
                        /* The ring is no longer full, clear busy flag. */
                        netif_wake_queue (dev);
                }