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

[Simon Horman]

On Tue, Jul 07, 2026 at 04:51:12PM +0200, Pablo Neira Ayuso wrote:
> 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@xxxxxxxxxx>
> > 
> > Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
> > 
> > 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.

Hi Pablo,

Of course you are correct.
Sorry for not realising this earlier.