netdev - [net-next 06/16] net/mlx5: Do not hold mutex while reading table constants

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Date:   Sat,  3 Apr 2021 21:19:44 -0700
From:   Saeed Mahameed <saeed@...nel.org>
To:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, Tariq Toukan <tariqt@...dia.com>,
        Parav Pandit <parav@...dia.com>,
        Saeed Mahameed <saeedm@...dia.com>
Subject: [net-next 06/16] net/mlx5: Do not hold mutex while reading table constants

From: Parav Pandit <parav@...dia.com>

Table max_size, min and max rate are constants initialized while table
is created. Reading it doesn't need to hold a table mutex. Hence, read
them without holding table mutex.

Signed-off-by: Parav Pandit <parav@...dia.com>
Signed-off-by: Saeed Mahameed <saeedm@...dia.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/rl.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/rl.c b/drivers/net/ethernet/mellanox/mlx5/core/rl.c
index 99039c47ef33..2accc0f324f3 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/rl.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/rl.c
@@ -180,16 +180,18 @@ int mlx5_rl_add_rate_raw(struct mlx5_core_dev *dev, void *rl_in, u16 uid,
 	int err = 0;
 	u32 rate;
 
-	rate = MLX5_GET(set_pp_rate_limit_context, rl_in, rate_limit);
-	mutex_lock(&table->rl_lock);
+	if (!table->max_size)
+		return -EOPNOTSUPP;
 
+	rate = MLX5_GET(set_pp_rate_limit_context, rl_in, rate_limit);
 	if (!rate || !mlx5_rl_is_in_range(dev, rate)) {
 		mlx5_core_err(dev, "Invalid rate: %u, should be %u to %u\n",
 			      rate, table->min_rate, table->max_rate);
-		err = -EINVAL;
-		goto out;
+		return -EINVAL;
 	}
 
+	mutex_lock(&table->rl_lock);
+
 	entry = find_rl_entry(table, rl_in, uid, dedicated_entry);
 	if (!entry) {
 		mlx5_core_err(dev, "Max number of %u rates reached\n",
-- 
2.30.2