From b5c9652ada33f39d47be7c502df72b14a1c95e9e Mon Sep 17 00:00:00 2001 From: Rahul Lakkireddy Date: Thu, 19 Mar 2020 23:08:10 +0530 Subject: [PATCH] cxgb4: fix Txq restart check during backpressure [ Upstream commit f1f20a8666c55cb534b8f3fc1130eebf01a06155 ] Driver reclaims descriptors in much smaller batches, even if hardware indicates more to reclaim, during backpressure. So, fix the check to restart the Txq during backpressure, by looking at how many descriptors hardware had indicated to reclaim, and not on how many descriptors that driver had actually reclaimed. Once the Txq is restarted, driver will reclaim even more descriptors when Tx path is entered again. Fixes: d429005fdf2c ("cxgb4/cxgb4vf: Add support for SGE doorbell queue timer") Signed-off-by: Rahul Lakkireddy Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/ethernet/chelsio/cxgb4/sge.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/chelsio/cxgb4/sge.c b/drivers/net/ethernet/chelsio/cxgb4/sge.c index 3af6d8376a66..3a45ac8f0e01 100644 --- a/drivers/net/ethernet/chelsio/cxgb4/sge.c +++ b/drivers/net/ethernet/chelsio/cxgb4/sge.c @@ -1324,8 +1324,9 @@ static inline void t6_fill_tnl_lso(struct sk_buff *skb, int t4_sge_eth_txq_egress_update(struct adapter *adap, struct sge_eth_txq *eq, int maxreclaim) { + unsigned int reclaimed, hw_cidx; struct sge_txq *q = &eq->q; - unsigned int reclaimed; + int hw_in_use; if (!q->in_use || !__netif_tx_trylock(eq->txq)) return 0; @@ -1333,12 +1334,17 @@ int t4_sge_eth_txq_egress_update(struct adapter *adap, struct sge_eth_txq *eq, /* Reclaim pending completed TX Descriptors. */ reclaimed = reclaim_completed_tx(adap, &eq->q, maxreclaim, true); + hw_cidx = ntohs(READ_ONCE(q->stat->cidx)); + hw_in_use = q->pidx - hw_cidx; + if (hw_in_use < 0) + hw_in_use += q->size; + /* If the TX Queue is currently stopped and there's now more than half * the queue available, restart it. Otherwise bail out since the rest * of what we want do here is with the possibility of shipping any * currently buffered Coalesced TX Work Request. */ - if (netif_tx_queue_stopped(eq->txq) && txq_avail(q) > (q->size / 2)) { + if (netif_tx_queue_stopped(eq->txq) && hw_in_use < (q->size / 2)) { netif_tx_wake_queue(eq->txq); eq->q.restarts++; }