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

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Date:   Sun, 23 Feb 2020 07:43:29 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     madhuparnabhowmik10@...il.com
Cc:     jiri@...lanox.com, davem@...emloft.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, joel@...lfernandes.org,
        frextrite@...il.com,
        linux-kernel-mentees@...ts.linuxfoundation.org, paulmck@...nel.org
Subject: Re: [PATCH] net: core: devlink.c: Hold devlink->lock from the
 beginning of devlink_dpipe_table_register()

Sat, Feb 22, 2020 at 07:52:34AM CET, madhuparnabhowmik10@...il.com wrote:
>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);

Please use "goto unlock" instead of unlocking on multiple places.



> 		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
>