Re: [PATCH net-next] gtp: annotate PDP lookups under RTNL

[Pablo Neira Ayuso <pablo@netfilter.org>]

Hi Simon,

On Tue, Jul 07, 2026 at 03:28:20PM +0100, Simon Horman wrote:
> On Wed, Jul 01, 2026 at 08:39:25PM +0800, Runyu Xiao wrote:
> > The GTP PDP lookup helpers are shared by RCU-protected data and report
> > paths and RTNL-protected control paths such as gtp_genl_new_pdp(). The
> > helpers walk RCU hlists, but they do not currently pass the RTNL
> > condition for the control-path lookups.
> > 
> > Pass lockdep_rtnl_is_held() to the PDP hlist iterators. Existing
> > RCU-reader callers remain valid because the RCU-list macros also accept
> > an active RCU read-side section; the added condition only documents the
> > non-RCU protection already used by RTNL control paths.
> > 
> > This was found by our static analysis tool and then manually reviewed
> > against the current tree. The dynamic triage evidence is a
> > target-matched CONFIG_PROVE_RCU_LIST warning; the change is limited
> > to documenting the existing protection contract.
> > 
> > This is a lockdep annotation cleanup. It does not change PDP lifetime or
> > hash updates.
> > 
> > Signed-off-by: Runyu Xiao <runyu.xiao@seu.edu.cn>
> 
> Reviewed-by: Simon Horman <horms@kernel.org>
> 
> There is an AI-generated review of this patch available on sashko.dev.
> While I don't believe that the issues raised there should impede progress
> of this patch you may want to look into them as possible follow-up.

This patch refers to the rtnl_lock, but it is the genetlink mutex that
protects updates on the PDP context list.

Then, from packet path, rcu lookups are performed.

I think this patch is not correct.