networking: make skb_push & __skb_push return void pointers

It seems like a historic accident that these return unsigned char *,
and in many places that means casts are required, more often than not.

Make these functions return void * and remove all the casts across
the tree, adding a (u8 *) cast only where the unsigned char pointer
was used directly, all done with the following spatch:

    @@
    expression SKB, LEN;
    typedef u8;
    identifier fn = { skb_push, __skb_push, skb_push_rcsum };
    @@
    - *(fn(SKB, LEN))
    + *(u8 *)fn(SKB, LEN)

    @@
    expression E, SKB, LEN;
    identifier fn = { skb_push, __skb_push, skb_push_rcsum };
    type T;
    @@
    - E = ((T *)(fn(SKB, LEN)))
    + E = fn(SKB, LEN)

    @@
    expression SKB, LEN;
    identifier fn = { skb_push, __skb_push, skb_push_rcsum };
    @@
    - fn(SKB, LEN)[0]
    + *(u8 *)fn(SKB, LEN)

Note that the last part there converts from push(...)[0] to the
more idiomatic *(u8 *)push(...).

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c
index b7c486752b3a..0c92ba0cbe0b 100644
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -1562,7 +1562,7 @@ static int ax25_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 
 	/* Add the PID if one is not supplied by the user in the skb */
 	if (!ax25->pidincl)
-		*skb_push(skb, 1) = sk->sk_protocol;
+		*(u8 *)skb_push(skb, 1) = sk->sk_protocol;
 
 	if (sk->sk_type == SOCK_SEQPACKET) {
 		/* Connected mode sockets go via the LAPB machine */