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/sctp/output.c b/net/sctp/output.c
index febcc350cf00..89cee1482d35 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -585,7 +585,7 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 	sctp_packet_set_owner_w(head, sk);
 
 	/* set sctp header */
-	sh = (struct sctphdr *)skb_push(head, sizeof(struct sctphdr));
+	sh = skb_push(head, sizeof(struct sctphdr));
 	skb_reset_transport_header(head);
 	sh->source = htons(packet->source_port);
 	sh->dest = htons(packet->destination_port);