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

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Date:   Fri, 21 Feb 2020 23:39:43 +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 | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index 3e8c94155d93..d54e1f156b6f 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -6840,6 +6840,8 @@ int devlink_dpipe_table_register(struct devlink *devlink,
 {
 	struct devlink_dpipe_table *table;
 
+	mutex_lock(&devlink->lock);
+
 	if (devlink_dpipe_table_find(&devlink->dpipe_table_list, table_name))
 		return -EEXIST;
 
@@ -6855,7 +6857,6 @@ int devlink_dpipe_table_register(struct devlink *devlink,
 	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