RE: selftests: net: l2tp.sh regression starting with 6.1-rc1

[Drewek, Wojciech]

> -----Original Message-----
> From: Guillaume Nault <gnault@xxxxxxxxxx>
> Sent: środa, 29 marca 2023 17:26
> To: Drewek, Wojciech <wojciech.drewek@xxxxxxxxx>
> Cc: Andrea Righi <andrea.righi@xxxxxxxxxxxxx>; David S. Miller <davem@xxxxxxxxxxxxx>; Eric Dumazet <edumazet@xxxxxxxxxx>;
> Jakub Kicinski <kuba@xxxxxxxxxx>; Paolo Abeni <pabeni@xxxxxxxxxx>; Shuah Khan <shuah@xxxxxxxxxx>; netdev@xxxxxxxxxxxxxxx;
> linux-kselftest@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: selftests: net: l2tp.sh regression starting with 6.1-rc1
> 
> On Wed, Mar 29, 2023 at 02:16:37PM +0000, Drewek, Wojciech wrote:
> > Hi,
> >
> > Modifying UAPI was not a good idea although the patch should not break userspace (related discussion [1]).
> > We could revert this patch with one additional change (include l2tp.h in net/sched/cls_flower.c) but then again,
> > modifying UAPI. This patch was mostly cosmetic anyway.
> > Second option is to try to fix the automatic load. I'm not an expert but I think
> > MODULE_ALIAS_NET_PF_PROTO macro is somehow responsible for that. I noticed some comments saying that
> > "__stringify doesn't like enums" (this macro is using _stringify) and my patch defined IPPROTO_L2TP in enum.
> > We can just replace IPPROTO_L2TP with 115 (where this macro is used) in order to fix this.
> > I'm going to give it a try and will let you know.
> 
> Yes, the modules aliases now have symbolic names:
> 
> $ modinfo l2tp_ip l2tp_ip6 | grep alias
> alias:          net-pf-2-proto-IPPROTO_L2TP
> alias:          net-pf-2-proto-2-type-IPPROTO_L2TP
> alias:          net-pf-10-proto-IPPROTO_L2TP
> alias:          net-pf-10-proto-2-type-IPPROTO_L2TP
> 
> Therefore, 'request_module("net-pf-%d-proto-%d-type-%d")' can't find
> them.
> 
> My personal preference is for the second option: fix module loading by
> using plain numbers in MODULE_ALIAS_*. We can always keep the symbolic
> names in comments.
> 
> ---- >8 ----
> 
> diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
> index 4db5a554bdbd..afe94a390ef0 100644
> --- a/net/l2tp/l2tp_ip.c
> +++ b/net/l2tp/l2tp_ip.c
> @@ -680,5 +680,5 @@ MODULE_VERSION("1.0");
>  /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
>   * enums
>   */
> -MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 2, IPPROTO_L2TP);
> -MODULE_ALIAS_NET_PF_PROTO(PF_INET, IPPROTO_L2TP);
> +MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 2, 115 /* IPPROTO_L2TP */);
> +MODULE_ALIAS_NET_PF_PROTO(PF_INET, 115 /* IPPROTO_L2TP */);
> diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
> index 2478aa60145f..65d106b41951 100644
> --- a/net/l2tp/l2tp_ip6.c
> +++ b/net/l2tp/l2tp_ip6.c
> @@ -809,5 +809,5 @@ MODULE_VERSION("1.0");
>  /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
>   * enums
>   */
> -MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);
> -MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);
> +MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, 115 /* IPPROTO_L2TP */);
> +MODULE_ALIAS_NET_PF_PROTO(PF_INET6, 115 /* IPPROTO_L2TP */);

Btw, am I blind or the alias with type was wrong the whole time?
pf goes first, then proto and type at the end according to the definition of MODULE_ALIAS_NET_PF_PROTO_TYPE
and here type (2) is 2nd and proto (115) is 3rd