From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
Date: Sun, 23 Feb 2020 16:52:33 +0530
Subject: net: core: devlink.c: Hold devlink->lock from the beginning of
 devlink_dpipe_table_register()
Patch-mainline: v5.6-rc4
Git-commit: 6132c1d9033d158bd0464e90bc46544fbe0bd6bc
References: bsc#1176447

devlink_dpipe_table_find() should be called under either
rcu_read_lock() or devlink->lock. devlink_dpipe_table_register()
calls devlink_dpipe_table_find() without holding the lock
and acquires it later. Therefore hold the devlink->lock
from the beginning of devlink_dpipe_table_register().

Suggested-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/core/devlink.c |   21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -6878,26 +6878,33 @@ int devlink_dpipe_table_register(struct
 				 void *priv, bool counter_control_extern)
 {
 	struct devlink_dpipe_table *table;
-
-	if (devlink_dpipe_table_find(&devlink->dpipe_table_list, table_name))
-		return -EEXIST;
+	int err = 0;
 
 	if (WARN_ON(!table_ops->size_get))
 		return -EINVAL;
 
+	mutex_lock(&devlink->lock);
+
+	if (devlink_dpipe_table_find(&devlink->dpipe_table_list, table_name)) {
+		err = -EEXIST;
+		goto unlock;
+	}
+
 	table = kzalloc(sizeof(*table), GFP_KERNEL);
-	if (!table)
-		return -ENOMEM;
+	if (!table) {
+		err = -ENOMEM;
+		goto unlock;
+	}
 
 	table->name = table_name;
 	table->table_ops = table_ops;
 	table->priv = priv;
 	table->counter_control_extern = counter_control_extern;
 
-	mutex_lock(&devlink->lock);
 	list_add_tail_rcu(&table->list, &devlink->dpipe_table_list);
+unlock:
 	mutex_unlock(&devlink->lock);
-	return 0;
+	return err;
 }
 EXPORT_SYMBOL_GPL(devlink_dpipe_table_register);