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, 2 insertions, 2 deletions

diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index df73190da761..8feff96a5bef 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -770,8 +770,8 @@ sctp_disposition_t sctp_sf_do_5_1D_ce(struct net *net,
 		auth.skb = chunk->auth_chunk;
 		auth.asoc = chunk->asoc;
 		auth.sctp_hdr = chunk->sctp_hdr;
-		auth.chunk_hdr = (sctp_chunkhdr_t *)skb_push(chunk->auth_chunk,
-					    sizeof(sctp_chunkhdr_t));
+		auth.chunk_hdr = skb_push(chunk->auth_chunk,
+					  sizeof(sctp_chunkhdr_t));
 		skb_pull(chunk->auth_chunk, sizeof(sctp_chunkhdr_t));
 		auth.transport = chunk->transport;