From: Ido Schimmel <idosch@mellanox.com>
Date: Fri, 21 Feb 2020 19:54:05 +0200
Subject: mlxsw: spectrum_mr: Protect multicast table list with a lock
Patch-mainline: v5.7-rc1
Git-commit: c366de85894f076b1790b24deec910c2503d9e01
References: bsc#1176774

The multicast table list is traversed from a delayed work that
periodically updates the kernel about packets and bytes statistics from
each multicast route.

The list is currently protected by RTNL, but subsequent patches will
remove the driver's dependence on this contended lock.

In order to be able to remove dependence on RTNL in the next patch,
guard this list with a dedicated mutex.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
 /* Copyright (c) 2017-2018 Mellanox Technologies. All rights reserved */
 
+#include <linux/mutex.h>
 #include <linux/rhashtable.h>
 #include <net/ipv6.h>
 
@@ -12,6 +13,7 @@ struct mlxsw_sp_mr {
 	void *catchall_route_priv;
 	struct delayed_work stats_update_dw;
 	struct list_head table_list;
+	struct mutex table_list_lock; /* Protects table_list */
 #define MLXSW_SP_MR_ROUTES_COUNTER_UPDATE_INTERVAL 5000 /* ms */
 	unsigned long priv[0];
 	/* priv has to be always the last item */
@@ -926,7 +928,9 @@ struct mlxsw_sp_mr_table *mlxsw_sp_mr_ta
 				       &catchall_route_params);
 	if (err)
 		goto err_ops_route_create;
+	mutex_lock(&mr->table_list_lock);
 	list_add_tail(&mr_table->node, &mr->table_list);
+	mutex_unlock(&mr->table_list_lock);
 	return mr_table;
 
 err_ops_route_create:
@@ -942,7 +946,9 @@ void mlxsw_sp_mr_table_destroy(struct ml
 	struct mlxsw_sp_mr *mr = mlxsw_sp->mr;
 
 	WARN_ON(!mlxsw_sp_mr_table_empty(mr_table));
+	mutex_lock(&mr->table_list_lock);
 	list_del(&mr_table->node);
+	mutex_unlock(&mr->table_list_lock);
 	mr->mr_ops->route_destroy(mlxsw_sp, mr->priv,
 				  &mr_table->catchall_route_priv);
 	rhashtable_destroy(&mr_table->route_ht);
@@ -1000,10 +1006,12 @@ static void mlxsw_sp_mr_stats_update(str
 	unsigned long interval;
 
 	rtnl_lock();
+	mutex_lock(&mr->table_list_lock);
 	list_for_each_entry(mr_table, &mr->table_list, node)
 		list_for_each_entry(mr_route, &mr_table->route_list, node)
 			mlxsw_sp_mr_route_stats_update(mr_table->mlxsw_sp,
 						       mr_route);
+	mutex_unlock(&mr->table_list_lock);
 	rtnl_unlock();
 
 	interval = msecs_to_jiffies(MLXSW_SP_MR_ROUTES_COUNTER_UPDATE_INTERVAL);
@@ -1023,6 +1031,7 @@ int mlxsw_sp_mr_init(struct mlxsw_sp *ml
 	mr->mr_ops = mr_ops;
 	mlxsw_sp->mr = mr;
 	INIT_LIST_HEAD(&mr->table_list);
+	mutex_init(&mr->table_list_lock);
 
 	err = mr_ops->init(mlxsw_sp, mr->priv);
 	if (err)
@@ -1034,6 +1043,7 @@ int mlxsw_sp_mr_init(struct mlxsw_sp *ml
 	mlxsw_core_schedule_dw(&mr->stats_update_dw, interval);
 	return 0;
 err:
+	mutex_destroy(&mr->table_list_lock);
 	kfree(mr);
 	return err;
 }
@@ -1044,5 +1054,6 @@ void mlxsw_sp_mr_fini(struct mlxsw_sp *m
 
 	cancel_delayed_work_sync(&mr->stats_update_dw);
 	mr->mr_ops->fini(mlxsw_sp, mr->priv);
+	mutex_destroy(&mr->table_list_lock);
 	kfree(mr);
 }