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

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Message-ID: <20200222062640.GA2228@nanopsycho>
Date:   Sat, 22 Feb 2020 07:26:40 +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()

Fri, Feb 21, 2020 at 07:09:43PM 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 | 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;

You have to handle the error path.


> 
>@@ -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
>