> I thought the correct use is to get this lock on clean_tx
> side which can get called on a different cpu on rx (which
> also cleans up slots for skbs that have finished xmit). Both
> TX and clean_tx uses the same tx_ring's head/tail ptrs and
> should be exclusive. But I don't find clean tx using this
> lock in the code, so I am confused :-)
>From e1000_main.c, e1000_clean():
/* e1000_clean is called per-cpu. This lock protects
* tx_ring[0] from being cleaned by multiple cpus
* simultaneously. A failure obtaining the lock means
* tx_ring[0] is currently being cleaned anyway. */
if (spin_trylock(&adapter->tx_queue_lock)) {
tx_cleaned = e1000_clean_tx_irq(adapter,
&adapter->tx_ring[0]);
spin_unlock(&adapter->tx_queue_lock);
}
In a multi-ring implementation of the driver, this is wrapped with for
(i = 0; i < adapter->num_tx_queues; i++) and &adapter->tx_ring[i]. This
lock also prevents the clean routine from stomping on xmit_frame() when
transmitting. Also in the multi-ring implementation, the tx_lock is
pushed down into the individual tx_ring struct, not at the adapter
level.
Cheers,
-PJ Waskiewicz
[EMAIL PROTECTED]
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