[PATCH v6] net/mlx5: fix mutex unlock in txpp cleanup

[Chengfeng Ye]

The lock sh->txpp.mutex was not correctly released on one path
of cleanup function return, potentially causing the deadlock.

Fixes: d133f4cdb7 ("net/mlx5: create clock queue for packet pacing")
Cc: sta...@dpdk.org

Signed-off-by: Chengfeng Ye <cy...@connect.ust.hk>
---
 drivers/net/mlx5/mlx5_txpp.c | 30 ++++++++++++------------------
 1 file changed, 12 insertions(+), 18 deletions(-)

diff --git a/drivers/net/mlx5/mlx5_txpp.c b/drivers/net/mlx5/mlx5_txpp.c
index 4f6da9f2d1..75c08c55e2 100644
--- a/drivers/net/mlx5/mlx5_txpp.c
+++ b/drivers/net/mlx5/mlx5_txpp.c
@@ -896,7 +896,6 @@ mlx5_txpp_start(struct rte_eth_dev *dev)
        struct mlx5_priv *priv = dev->data->dev_private;
        struct mlx5_dev_ctx_shared *sh = priv->sh;
        int err = 0;
-       int ret;
 
        if (!priv->config.tx_pp) {
                /* Packet pacing is not requested for the device. */
@@ -909,14 +908,14 @@ mlx5_txpp_start(struct rte_eth_dev *dev)
                return 0;
        }
        if (priv->config.tx_pp > 0) {
-               ret = rte_mbuf_dynflag_lookup
-                               (RTE_MBUF_DYNFLAG_TX_TIMESTAMP_NAME, NULL);
-               if (ret < 0)
+               err = rte_mbuf_dynflag_lookup
+                       (RTE_MBUF_DYNFLAG_TX_TIMESTAMP_NAME, NULL);
+               /* No flag registered means no service needed. */
+               if (err < 0)
                        return 0;
+               err = 0;
        }
-       ret = pthread_mutex_lock(&sh->txpp.mutex);
-       MLX5_ASSERT(!ret);
-       RTE_SET_USED(ret);
+       claim_zero(pthread_mutex_lock(&sh->txpp.mutex));
        if (sh->txpp.refcnt) {
                priv->txpp_en = 1;
                ++sh->txpp.refcnt;
@@ -930,9 +929,7 @@ mlx5_txpp_start(struct rte_eth_dev *dev)
                        rte_errno = -err;
                }
        }
-       ret = pthread_mutex_unlock(&sh->txpp.mutex);
-       MLX5_ASSERT(!ret);
-       RTE_SET_USED(ret);
+       claim_zero(pthread_mutex_unlock(&sh->txpp.mutex));
        return err;
 }
 
@@ -950,24 +947,21 @@ mlx5_txpp_stop(struct rte_eth_dev *dev)
 {
        struct mlx5_priv *priv = dev->data->dev_private;
        struct mlx5_dev_ctx_shared *sh = priv->sh;
-       int ret;
 
        if (!priv->txpp_en) {
                /* Packet pacing is already disabled for the device. */
                return;
        }
        priv->txpp_en = 0;
-       ret = pthread_mutex_lock(&sh->txpp.mutex);
-       MLX5_ASSERT(!ret);
-       RTE_SET_USED(ret);
+       claim_zero(pthread_mutex_lock(&sh->txpp.mutex));
        MLX5_ASSERT(sh->txpp.refcnt);
-       if (!sh->txpp.refcnt || --sh->txpp.refcnt)
+       if (!sh->txpp.refcnt || --sh->txpp.refcnt) {
+               claim_zero(pthread_mutex_unlock(&sh->txpp.mutex));
                return;
+       }
        /* No references any more, do actual destroy. */
        mlx5_txpp_destroy(sh);
-       ret = pthread_mutex_unlock(&sh->txpp.mutex);
-       MLX5_ASSERT(!ret);
-       RTE_SET_USED(ret);
+       claim_zero(pthread_mutex_unlock(&sh->txpp.mutex));
 }
 
 /*
-- 
2.17.1