netdev - [PATCH] net: core: devlink.c: Hold devlink->lock from the beginning of devlink_dpipe_table

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Date:   Sat, 22 Feb 2020 12:22:34 +0530
From:   madhuparnabhowmik10@...il.com
To:     jiri@...lanox.com, davem@...emloft.net
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        joel@...lfernandes.org, frextrite@...il.com,
        linux-kernel-mentees@...ts.linuxfoundation.org, paulmck@...nel.org,
        Madhuparna Bhowmik <madhuparnabhowmik10@...il.com>
Subject: [PATCH] net: core: devlink.c: Hold devlink->lock from the beginning of devlink_dpipe_table_register()

From: Madhuparna Bhowmik <madhuparnabhowmik10@...il.com>

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@...lanox.com>
Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@...il.com>
---
 net/core/devlink.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index 3e8c94155d93..ba9dd8cb98c3 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -6840,22 +6840,29 @@ int devlink_dpipe_table_register(struct devlink *devlink,
 {
 	struct devlink_dpipe_table *table;
 
-	if (devlink_dpipe_table_find(&devlink->dpipe_table_list, table_name))
+	mutex_lock(&devlink->lock);
+
+	if (devlink_dpipe_table_find(&devlink->dpipe_table_list, table_name)) {
+		mutex_unlock(&devlink->lock);
 		return -EEXIST;
+	}
 
-	if (WARN_ON(!table_ops->size_get))
+	if (WARN_ON(!table_ops->size_get)) {
+		mutex_unlock(&devlink->lock);
 		return -EINVAL;
+	}
 
 	table = kzalloc(sizeof(*table), GFP_KERNEL);
-	if (!table)
+	if (!table) {
+		mutex_unlock(&devlink->lock);
 		return -ENOMEM;
+	}
 
 	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);
 	mutex_unlock(&devlink->lock);
 	return 0;
-- 
2.17.1