net: Introduce possible_net_t

Having to say
> #ifdef CONFIG_NET_NS
> 	struct net *net;
> #endif

in structures is a little bit wordy and a little bit error prone.

Instead it is possible to say:
> typedef struct {
> #ifdef CONFIG_NET_NS
>       struct net *net;
> #endif
> } possible_net_t;

And then in a header say:

> 	possible_net_t net;

Which is cleaner and easier to use and easier to test, as the
possible_net_t is always there no matter what the compile options.

Further this allows read_pnet and write_pnet to be functions in all
cases which is better at catching typos.

This change adds possible_net_t, updates the definitions of read_pnet
and write_pnet, updates optional struct net * variables that
write_pnet uses on to have the type possible_net_t, and finally fixes
up the b0rked users of read_pnet and write_pnet.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 3 deletions

diff --git a/include/net/sock.h b/include/net/sock.h
index 95b2c1c220f9..9411c3421dd3 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -190,9 +190,7 @@ struct sock_common {
 		struct hlist_nulls_node skc_portaddr_node;
 	};
 	struct proto		*skc_prot;
-#ifdef CONFIG_NET_NS
-	struct net	 	*skc_net;
-#endif
+	possible_net_t		skc_net;
 
 #if IS_ENABLED(CONFIG_IPV6)
 	struct in6_addr		skc_v6_daddr;