Re: [PATCH ovpn-net] ovpn: fix incorrect use of rcu_access_pointer()

Hi,
On 2026/7/22 16:21, Antonio Quartulli wrote:
> Hi!
>
> On 22/07/2026 03:56, Qingfang Deng wrote:
>> rcu_access_pointer() should only be used to test the value of a pointer,
>> not to dereference it. Use rcu_dereference() instead. No extra
>> rcu_read_lock() is needed here, as the spin_lock_bh() above marks an RCU
>> critical section.
>>
>> Fixes: f6226ae7a0cd ("ovpn: introduce the ovpn_socket object")
>> Signed-off-by: Qingfang Deng <[email protected]>
>> ---
>>   drivers/net/ovpn/peer.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ovpn/peer.c b/drivers/net/ovpn/peer.c
>> index a09d61296425..8de737579112 100644
>> --- a/drivers/net/ovpn/peer.c
>> +++ b/drivers/net/ovpn/peer.c
>> @@ -1164,7 +1164,7 @@ static void ovpn_peer_release_p2p(struct 
>> ovpn_priv *ovpn, struct sock *sk,
>>       }
>>         if (sk) {
>> -        ovpn_sock = rcu_access_pointer(peer->sock);
>> +        ovpn_sock = rcu_dereference(peer->sock);
>
> Sashiko says:
>
> Using `rcu_dereference()` instead of `rcu_dereference_bh()` under 
> `spin_lock_bh()` triggers a lockdep warning.
>
I think `rcu_dereference()` has more relax checks than 
`rcu_dereference_bh()` and Sashiko is wrong, i.e. using 
`rcu_dereference()` in a BH-disabled context is okay, but using 
`rcu_dereference_bh()` in a process context with only `rcu_read_lock()` 
is _not_ okay. Can you verify that?

Best regards,

Qingfang



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