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* [dpdk-stable] [PATCH] net/ixgbe: fix RxQ/TxQ release
@ 2021-09-27 17:18 Julien Meunier
  2021-09-28  3:06 ` Wang, Haiyue
  2021-09-28  8:12 ` [dpdk-stable] [PATCH v2] " Julien Meunier
  0 siblings, 2 replies; 7+ messages in thread
From: Julien Meunier @ 2021-09-27 17:18 UTC (permalink / raw)
  To: dev; +Cc: stable, bruce.richardson, Haiyue Wang

On the vector implementation, during the tear-down, the mbufs not
drained in the RxQ and TxQ are freed based on an algorithm which
supposed that the number of descriptors is a power of 2 (max_desc).
Based on this hypothesis, this algorithm uses a bitmask in order to
detect an index overflow during the iteration, and to restart the loop
from 0.

However, there is no such power of 2 requirement in the ixgbe for the
number of descriptors in the RxQ / TxQ. The only requirement is to have
a number correctly aligned.

If a user requested to configure a number of descriptors which is not a
power of 2, as a consequence, during the tear-down, it was possible to
be in an infinite loop, and to never reach the exit loop condition.

By removing the bitmask and changing the loop method, we can avoid this
issue, and allow the user to configure a RxQ / TxQ which is not a power
of 2.

Fixes: c95584dc2b18 ("ixgbe: new vectorized functions for Rx/Tx")
Cc: bruce.richardson@intel.com
Cc: stable@dpdk.org

Signed-off-by: Julien Meunier <julien.meunier@nokia.com>
---
 drivers/net/ixgbe/ixgbe_rxtx_vec_common.h | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ixgbe/ixgbe_rxtx_vec_common.h b/drivers/net/ixgbe/ixgbe_rxtx_vec_common.h
index adba855ca3..8912558918 100644
--- a/drivers/net/ixgbe/ixgbe_rxtx_vec_common.h
+++ b/drivers/net/ixgbe/ixgbe_rxtx_vec_common.h
@@ -150,11 +150,14 @@ _ixgbe_tx_queue_release_mbufs_vec(struct ixgbe_tx_queue *txq)
 		return;
 
 	/* release the used mbufs in sw_ring */
-	for (i = txq->tx_next_dd - (txq->tx_rs_thresh - 1);
-	     i != txq->tx_tail;
-	     i = (i + 1) & max_desc) {
+	i = txq->tx_next_dd - (txq->tx_rs_thresh - 1);
+	while (i != txq->tx_tail) {
 		txe = &txq->sw_ring_v[i];
 		rte_pktmbuf_free_seg(txe->mbuf);
+
+		i = i + 1;
+		if (i > max_desc)
+			i = 0;
 	}
 	txq->nb_tx_free = max_desc;
 
@@ -168,7 +171,7 @@ _ixgbe_tx_queue_release_mbufs_vec(struct ixgbe_tx_queue *txq)
 static inline void
 _ixgbe_rx_queue_release_mbufs_vec(struct ixgbe_rx_queue *rxq)
 {
-	const unsigned int mask = rxq->nb_rx_desc - 1;
+	const unsigned int max_desc = rxq->nb_rx_desc - 1;
 	unsigned int i;
 
 	if (rxq->sw_ring == NULL || rxq->rxrearm_nb >= rxq->nb_rx_desc)
@@ -181,11 +184,14 @@ _ixgbe_rx_queue_release_mbufs_vec(struct ixgbe_rx_queue *rxq)
 				rte_pktmbuf_free_seg(rxq->sw_ring[i].mbuf);
 		}
 	} else {
-		for (i = rxq->rx_tail;
-		     i != rxq->rxrearm_start;
-		     i = (i + 1) & mask) {
+		i = rxq->rx_tail;
+		while (i != rxq->rxrearm_start) {
 			if (rxq->sw_ring[i].mbuf != NULL)
 				rte_pktmbuf_free_seg(rxq->sw_ring[i].mbuf);
+
+			i = i + 1;
+			if (i > max_desc)
+				i = 0;
 		}
 	}
 
-- 
2.17.1


^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2021-10-09  4:43 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-27 17:18 [dpdk-stable] [PATCH] net/ixgbe: fix RxQ/TxQ release Julien Meunier
2021-09-28  3:06 ` Wang, Haiyue
2021-09-28  3:21   ` Wang, Haiyue
2021-09-28  7:46     ` Julien Meunier
2021-09-28  8:12 ` [dpdk-stable] [PATCH v2] " Julien Meunier
2021-09-28 12:18   ` Wang, Haiyue
2021-10-09  4:43     ` Zhang, Qi Z

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