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>

4 files changed, 6 insertions, 6 deletions

diff --git a/drivers/net/ppp/ppp_async.c b/drivers/net/ppp/ppp_async.c
index 32c72db654e2..814fd8fae67d 100644
--- a/drivers/net/ppp/ppp_async.c
+++ b/drivers/net/ppp/ppp_async.c
@@ -802,7 +802,7 @@ process_input_packet(struct asyncppp *ap)
 	proto = p[0];
 	if (proto & 1) {
 		/* protocol is compressed */
-		skb_push(skb, 1)[0] = 0;
+		*(u8 *)skb_push(skb, 1) = 0;
 	} else {
 		if (skb->len < 2)
 			goto err;
diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index bbded33120fe..d42091f11eb8 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -1490,7 +1490,7 @@ ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
 		/* check if we should pass this packet */
 		/* the filter instructions are constructed assuming
 		   a four-byte PPP header on each packet */
-		*skb_push(skb, 2) = 1;
+		*(u8 *)skb_push(skb, 2) = 1;
 		if (ppp->pass_filter &&
 		    BPF_PROG_RUN(ppp->pass_filter, skb) == 0) {
 			if (ppp->debug & 1)
@@ -2133,7 +2133,7 @@ ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
 			if (skb_unclone(skb, GFP_ATOMIC))
 				goto err;
 
-			*skb_push(skb, 2) = 0;
+			*(u8 *)skb_push(skb, 2) = 0;
 			if (ppp->pass_filter &&
 			    BPF_PROG_RUN(ppp->pass_filter, skb) == 0) {
 				if (ppp->debug & 1)
@@ -2267,7 +2267,7 @@ ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
 	 * Do protocol ID decompression on the first fragment of each packet.
 	 */
 	if ((PPP_MP_CB(skb)->BEbits & B) && (skb->data[0] & 1))
-		*skb_push(skb, 1) = 0;
+		*(u8 *)skb_push(skb, 1) = 0;
 
 	/*
 	 * Expand sequence number to 32 bits, making it as close
diff --git a/drivers/net/ppp/ppp_synctty.c b/drivers/net/ppp/ppp_synctty.c
index ce2300c0bcbf..ef08590db873 100644
--- a/drivers/net/ppp/ppp_synctty.c
+++ b/drivers/net/ppp/ppp_synctty.c
@@ -711,7 +711,7 @@ ppp_sync_input(struct syncppp *ap, const unsigned char *buf,
 	/* decompress protocol field if compressed */
 	if (p[0] & 1) {
 		/* protocol is compressed */
-		skb_push(skb, 1)[0] = 0;
+		*(u8 *)skb_push(skb, 1) = 0;
 	} else if (skb->len < 2)
 		goto err;
 
diff --git a/drivers/net/ppp/pptp.c b/drivers/net/ppp/pptp.c
index 1951b1085cb8..2f22e318a67f 100644
--- a/drivers/net/ppp/pptp.c
+++ b/drivers/net/ppp/pptp.c
@@ -328,7 +328,7 @@ allow_packet:
 
 		if ((*skb->data) & 1) {
 			/* protocol is compressed */
-			skb_push(skb, 1)[0] = 0;
+			*(u8 *)skb_push(skb, 1) = 0;
 		}
 
 		skb->ip_summed = CHECKSUM_NONE;