Messages in this thread Patch in this message | | | From | Eric Dumazet <> | Date | Thu, 9 Mar 2023 16:05:13 +0100 | Subject | Re: [PATCH net-next v6 4/5] ip_tunnel: Preserve pointer const in ip_tunnel_info_opts |
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On Thu, Mar 9, 2023 at 3:59 PM Eric Dumazet <edumazet@google.com> wrote: > > On Thu, Mar 9, 2023 at 2:48 PM Gavin Li <gavinl@nvidia.com> wrote: > > > > Change ip_tunnel_info_opts( ) from static function to macro to cast return > > value and preserve the const-ness of the pointer. > > > > Signed-off-by: Gavin Li <gavinl@nvidia.com> > > --- > > include/net/ip_tunnels.h | 11 ++++++----- > > 1 file changed, 6 insertions(+), 5 deletions(-) > > > > diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h > > index fca357679816..3e5c102b841f 100644 > > --- a/include/net/ip_tunnels.h > > +++ b/include/net/ip_tunnels.h > > @@ -67,6 +67,12 @@ struct ip_tunnel_key { > > GENMASK((sizeof_field(struct ip_tunnel_info, \ > > options_len) * BITS_PER_BYTE) - 1, 0) > > > > +#define ip_tunnel_info_opts(info) \ > > + _Generic(info, \ > > + const typeof(*(info)) * : ((const void *)((info) + 1)),\ > > + default : ((void *)((info) + 1)) \ > > + ) > > + > > Hmm... > > This looks quite dangerous, we lost type safety with the 'default' > case, with all these casts. > > What about using something cleaner instead ? > > (Not sure why we do not have an available generic helper for this kind > of repetitive things) >
Or more exactly :
diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h index fca3576798166416982ee6a9100b003810c49830..17fc6c8f7e0b9e5303c1fb9e5dad77c5310e01a9 100644 --- a/include/net/ip_tunnels.h +++ b/include/net/ip_tunnels.h @@ -485,10 +485,11 @@ static inline void iptunnel_xmit_stats(struct net_device *dev, int pkt_len) } }
-static inline void *ip_tunnel_info_opts(struct ip_tunnel_info *info) -{ - return info + 1; -} +#define ip_tunnel_info_opts(info) \ + (_Generic(info, \ + const struct ip_tunnel_info * : (const void *)((info) + 1), \ + struct ip_tunnel_info * : (void *)((info) + 1)) \ + )
static inline void ip_tunnel_info_opts_get(void *to, const struct ip_tunnel_info *info)
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