linux-kernel - [PATCH 5.4 285/320] Revert "net/mlx5: Add retry mechanism to the command entry index allocation"

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Message-Id: <20220124184003.661305647@linuxfoundation.org>
Date:   Mon, 24 Jan 2022 19:44:29 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Moshe Shemesh <moshe@...dia.com>,
        Eran Ben Elisha <eranbe@...dia.com>,
        Saeed Mahameed <saeedm@...dia.com>
Subject: [PATCH 5.4 285/320] Revert "net/mlx5: Add retry mechanism to the command entry index allocation"

From: Moshe Shemesh <moshe@...dia.com>

commit 4f6626b0e140867fd6d5a2e9d4ceaef97f10f46a upstream.

This reverts commit 410bd754cd73c4a2ac3856d9a03d7b08f9c906bf.

The reverted commit had added a retry mechanism to the command entry
index allocation. The previous patch ensures that there is a free
command entry index once the command work handler holds the command
semaphore. Thus the retry mechanism is not needed.

Fixes: 410bd754cd73 ("net/mlx5: Add retry mechanism to the command entry index allocation")
Signed-off-by: Moshe Shemesh <moshe@...dia.com>
Reviewed-by: Eran Ben Elisha <eranbe@...dia.com>
Signed-off-by: Saeed Mahameed <saeedm@...dia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/ethernet/mellanox/mlx5/core/cmd.c |   21 +--------------------
 1 file changed, 1 insertion(+), 20 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/cmd.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/cmd.c
@@ -887,25 +887,6 @@ static bool opcode_allowed(struct mlx5_c
 	return cmd->allowed_opcode == opcode;
 }
 
-static int cmd_alloc_index_retry(struct mlx5_cmd *cmd)
-{
-	unsigned long alloc_end = jiffies + msecs_to_jiffies(1000);
-	int idx;
-
-retry:
-	idx = cmd_alloc_index(cmd);
-	if (idx < 0 && time_before(jiffies, alloc_end)) {
-		/* Index allocation can fail on heavy load of commands. This is a temporary
-		 * situation as the current command already holds the semaphore, meaning that
-		 * another command completion is being handled and it is expected to release
-		 * the entry index soon.
-		 */
-		cpu_relax();
-		goto retry;
-	}
-	return idx;
-}
-
 static void cmd_work_handler(struct work_struct *work)
 {
 	struct mlx5_cmd_work_ent *ent = container_of(work, struct mlx5_cmd_work_ent, work);
@@ -923,7 +904,7 @@ static void cmd_work_handler(struct work
 	sem = ent->page_queue ? &cmd->pages_sem : &cmd->sem;
 	down(sem);
 	if (!ent->page_queue) {
-		alloc_ret = cmd_alloc_index_retry(cmd);
+		alloc_ret = cmd_alloc_index(cmd);
 		if (alloc_ret < 0) {
 			mlx5_core_err(dev, "failed to allocate command entry\n");
 			if (ent->callback) {