netdev - Re: [PATCH net] net: bridge: annotate data-race in br_fdb

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Message-ID: <f3bf9a76-c110-481a-a89a-c54d5856cfe3@blackwall.org>
Date: Tue, 6 Jan 2026 23:26:35 +0200
From: Nikolay Aleksandrov <razor@...ckwall.org>
To: Eric Dumazet <edumazet@...gle.com>, "David S . Miller"
 <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>, netdev@...r.kernel.org,
 eric.dumazet@...il.com
Subject: Re: [PATCH net] net: bridge: annotate data-race in br_fdb_update()

On 06/01/2026 21:40, Eric Dumazet wrote:
> fdb->updated is read and written locklessly.
> 
> Add READ_ONCE()/WRITE_ONCE() annotations.
> 
> Fixes: 31cbc39b6344 ("net: bridge: add option to allow activity notifications for any fdb entries")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: Nikolay Aleksandrov <razor@...ckwall.org>
> ---
>   net/bridge/br_fdb.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
> index 58d22e2b85fc3551bd5aec9c20296ddfcecaa040..e7bd20f0e8d6b7b24aef43d7bed34adf171c34a8 100644
> --- a/net/bridge/br_fdb.c
> +++ b/net/bridge/br_fdb.c
> @@ -1002,8 +1002,8 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
>   			unsigned long now = jiffies;
>   			bool fdb_modified = false;
>   
> -			if (now != fdb->updated) {
> -				fdb->updated = now;
> +			if (now != READ_ONCE(fdb->updated)) {
> +				WRITE_ONCE(fdb->updated, now);
>   				fdb_modified = __fdb_mark_active(fdb);
>   			}
>   

Thanks,
Acked-by: Nikolay Aleksandrov <razor@...ckwall.org>