Re: [PATCH net-next v3 4/4] net: bonding: add the READ_ONCE/WRITE_ONCE for outside lock accessing

[Hangbin Liu <liuhangbin@gmail.com>]

On Sun, Nov 30, 2025 at 03:48:46PM +0800, Tonghao Zhang wrote:
> Although operations on the variable send_peer_notif are already within
> a lock-protected critical section, there are cases where it is accessed
> outside the lock. Therefore, READ_ONCE() and WRITE_ONCE() should be
> added to it.
> 
> Cc: Jay Vosburgh <jv@jvosburgh.net>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: Simon Horman <horms@kernel.org>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: Andrew Lunn <andrew+netdev@lunn.ch>
> Cc: Nikolay Aleksandrov <razor@blackwall.org>
> Cc: Hangbin Liu <liuhangbin@gmail.com>
> Cc: Jason Xing <kerneljasonxing@gmail.com>
> Signed-off-by: Tonghao Zhang <tonghao@bamaicloud.com>
> ---
> v2: fix compilation errors
> ---
>  drivers/net/bonding/bond_main.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 025ca0a45615..14396e39b1f0 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -1204,8 +1204,9 @@ void bond_peer_notify_work_rearm(struct bonding *bond, unsigned long delay)
>  /* Peer notify update handler. Holds only RTNL */
>  static void bond_peer_notify_reset(struct bonding *bond)
>  {
> -	bond->send_peer_notif = bond->params.num_peer_notif *
> -		max(1, bond->params.peer_notif_delay);
> +	WRITE_ONCE(bond->send_peer_notif,
> +		   bond->params.num_peer_notif *
> +		   max(1, bond->params.peer_notif_delay));
>  }
>  
>  static void bond_peer_notify_handler(struct work_struct *work)
> @@ -2825,7 +2826,7 @@ static void bond_mii_monitor(struct work_struct *work)
>  
>  	rcu_read_unlock();
>  
> -	if (commit || bond->send_peer_notif) {
> +	if (commit || READ_ONCE(bond->send_peer_notif)) {
>  		/* Race avoidance with bond_close cancel of workqueue */
>  		if (!rtnl_trylock()) {
>  			delay = 1;
> @@ -3784,7 +3785,7 @@ static void bond_activebackup_arp_mon(struct bonding *bond)
>  	should_notify_rtnl = bond_ab_arp_probe(bond);
>  	rcu_read_unlock();
>  
> -	if (bond->send_peer_notif || should_notify_rtnl) {
> +	if (READ_ONCE(bond->send_peer_notif) || should_notify_rtnl) {
>  		if (!rtnl_trylock()) {
>  			delta_in_ticks = 1;
>  			goto re_arm;
> -- 
> 2.34.1
> 

Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>