net/mlx5: HWS, use lock classes for bwc locks

The HWS BWC API uses one lock per queue and usually acquires one of
them, except when doing changes which require locking all queues in
order. Naturally, lockdep isn't too happy about acquiring the same lock
class multiple times, so inform it that each queue lock is a different
class to avoid false positives.

Fixes: 2ca62599 ("net/mlx5: HWS, added send engine and context handling")
Signed-off-by: Cosmin Ratiu <cratiu@nvidia.com>
Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/mellanox/mlx5/core/steering/hws/mlx5hws_context.h

@@ -46,6 +46,7 @@ struct mlx5hws_context {
 	struct mlx5hws_send_engine *send_queue;
 	size_t queues;
 	struct mutex *bwc_send_queue_locks; /* protect BWC queues */
+	struct lock_class_key *bwc_lock_class_keys;
 	struct list_head tbl_list;
 	struct mlx5hws_context_debug_info debug_info;
 	struct xarray peer_ctx_xa;

drivers/net/ethernet/mellanox/mlx5/core/steering/hws/mlx5hws_send.c

@@ -947,8 +947,12 @@ static void hws_send_queues_bwc_locks_destroy(struct mlx5hws_context *ctx)
 	if (!mlx5hws_context_bwc_supported(ctx))
 		return;
 
-	for (i = 0; i < bwc_queues; i++)
+	for (i = 0; i < bwc_queues; i++) {
 		mutex_destroy(&ctx->bwc_send_queue_locks[i]);
+		lockdep_unregister_key(ctx->bwc_lock_class_keys + i);
+	}
+
+	kfree(ctx->bwc_lock_class_keys);
 	kfree(ctx->bwc_send_queue_locks);
 }
 
@@ -977,10 +981,22 @@ static int hws_bwc_send_queues_init(struct mlx5hws_context *ctx)
 	if (!ctx->bwc_send_queue_locks)
 		return -ENOMEM;
 
-	for (i = 0; i < bwc_queues; i++)
+	ctx->bwc_lock_class_keys = kcalloc(bwc_queues,
+					   sizeof(*ctx->bwc_lock_class_keys),
+					   GFP_KERNEL);
+	if (!ctx->bwc_lock_class_keys)
+		goto err_lock_class_keys;
+
+	for (i = 0; i < bwc_queues; i++) {
 		mutex_init(&ctx->bwc_send_queue_locks[i]);
+		lockdep_register_key(ctx->bwc_lock_class_keys + i);
+	}
 
 	return 0;
+
+err_lock_class_keys:
+	kfree(ctx->bwc_send_queue_locks);
+	return -ENOMEM;
 }
 
 int mlx5hws_send_queues_open(struct mlx5hws_context *ctx,