Messages in this thread Patch in this message | | | From | Divy Le Ray <> | Subject | [PATCH 2.6.25] - Fix transmit queue stop mechanism | Date | Thu, 13 Mar 2008 00:13:30 -0700 |
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From: Divy Le Ray <divy@chelsio.com>
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: Divy Le Ray <divy@chelsio.com> ---
drivers/net/cxgb3/sge.c | 12 +++++++++--- 1 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/net/cxgb3/sge.c b/drivers/net/cxgb3/sge.c index 979f3fc..db58687 100644 --- a/drivers/net/cxgb3/sge.c +++ b/drivers/net/cxgb3/sge.c @@ -1107,9 +1107,15 @@ int t3_eth_xmit(struct sk_buff *skb, struct net_device *dev) } q->in_use += ndesc; - if (unlikely(credits - ndesc < q->stop_thres)) - if (USE_GTS || !should_restart_tx(q)) - t3_stop_queue(dev, qs, q); + if (unlikely(credits - ndesc < q->stop_thres)) { + 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; q->unacked += ndesc;
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