[dpdk-dev] [PATCH v4 4/4] regex/mlx5: prevent wrong calculation of free sqs in umr mode

Suanming Mou suanmingm at nvidia.com
Wed Mar 31 09:37:49 CEST 2021


From: John Hurley <jhurley at nvidia.com>

A recent change adds support for scattered mbuf and UMR support for regex.
Part of this commit makes the pi and ci counters of the regex_sq a quarter
of the length in non umr mode, effectively moving them from 16 bits to
14. The new get_free method casts the difference in pi and ci to a 16 bit
value when calculating the free send queues, accounting for any wrapping
when pi has looped back to 0 but ci has not yet. However, the move to 14
bits while still casting to 16 can now lead to corrupted, large values
returned.

Modify the get_free function to take in the has_umr flag and, accordingly,
account for wrapping on either 14 or 16 bit pi/ci difference.

Fixes: 017f097021a6 ("regex/mlx5: add data path scattered mbuf process")
Signed-off-by: John Hurley <jhurley at nvidia.com>
Acked-by: Ori Kam <orika at nvidia.com>
---
 drivers/regex/mlx5/mlx5_regex_fastpath.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/regex/mlx5/mlx5_regex_fastpath.c b/drivers/regex/mlx5/mlx5_regex_fastpath.c
index 4f9402c583..b57e7d7794 100644
--- a/drivers/regex/mlx5/mlx5_regex_fastpath.c
+++ b/drivers/regex/mlx5/mlx5_regex_fastpath.c
@@ -192,8 +192,10 @@ send_doorbell(struct mlx5_regex_priv *priv, struct mlx5_regex_sq *sq)
 }
 
 static inline int
-get_free(struct mlx5_regex_sq *sq) {
-	return (sq_size_get(sq) - (uint16_t)(sq->pi - sq->ci));
+get_free(struct mlx5_regex_sq *sq, uint8_t has_umr) {
+	return (sq_size_get(sq) - ((sq->pi - sq->ci) &
+			(has_umr ? (MLX5_REGEX_MAX_WQE_INDEX >> 2) :
+			MLX5_REGEX_MAX_WQE_INDEX)));
 }
 
 static inline uint32_t
@@ -385,7 +387,7 @@ mlx5_regexdev_enqueue_gga(struct rte_regexdev *dev, uint16_t qp_id,
 	while ((sqid = ffs(queue->free_sqs))) {
 		sqid--; /* ffs returns 1 for bit 0 */
 		sq = &queue->sqs[sqid];
-		nb_desc = get_free(sq);
+		nb_desc = get_free(sq, priv->has_umr);
 		if (nb_desc) {
 			/* The ops be handled can't exceed nb_ops. */
 			if (nb_desc > nb_left)
@@ -418,7 +420,7 @@ mlx5_regexdev_enqueue(struct rte_regexdev *dev, uint16_t qp_id,
 	while ((sqid = ffs(queue->free_sqs))) {
 		sqid--; /* ffs returns 1 for bit 0 */
 		sq = &queue->sqs[sqid];
-		while (get_free(sq)) {
+		while (get_free(sq, priv->has_umr)) {
 			job_id = job_id_get(sqid, sq_size_get(sq), sq->pi);
 			prep_one(priv, queue, sq, ops[i], &queue->jobs[job_id]);
 			i++;
-- 
2.25.1



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