Commit cd7e9034 authored by Divy Le Ray's avatar Divy Le Ray Committed by Jeff Garzik

cxgb3: Fix transmit queue stop mechanism

The last change in the Tx queue stop mechanism opens a window
where the Tx queue might be stopped after pending credits
returned.

Tx credits are returned via a control message generated by the HW.
It returns tx credits on demand, triggered by a completion bit
set in selective transmit packet headers.

The current code can lead to the Tx queue stopped
with all pending credits returned, and the current frame
not triggering a credit return. The Tx queue will then never be
awaken.

The driver could alternatively request a completion for packets
that stop the queue. It's however safer at this point to go back
to the pre-existing behaviour.
Signed-off-by: default avatarDivy Le Ray <divy@chelsio.com>
Signed-off-by: default avatarJeff Garzik <jeff@garzik.org>
parent cdb34697
...@@ -1107,9 +1107,15 @@ int t3_eth_xmit(struct sk_buff *skb, struct net_device *dev) ...@@ -1107,9 +1107,15 @@ int t3_eth_xmit(struct sk_buff *skb, struct net_device *dev)
} }
q->in_use += ndesc; q->in_use += ndesc;
if (unlikely(credits - ndesc < q->stop_thres)) if (unlikely(credits - ndesc < q->stop_thres)) {
if (USE_GTS || !should_restart_tx(q)) t3_stop_queue(dev, qs, q);
t3_stop_queue(dev, qs, q);
if (should_restart_tx(q) &&
test_and_clear_bit(TXQ_ETH, &qs->txq_stopped)) {
q->restarts++;
netif_wake_queue(dev);
}
}
gen = q->gen; gen = q->gen;
q->unacked += ndesc; q->unacked += ndesc;
......
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