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>

3 files changed, 6 insertions, 6 deletions

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 29be2466970c..37c1e34ddd85 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -441,7 +441,7 @@ void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 		ip6h->saddr = np->local_ip.in6;
 		ip6h->daddr = np->remote_ip.in6;
 
-		eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
+		eth = skb_push(skb, ETH_HLEN);
 		skb_reset_mac_header(skb);
 		skb->protocol = eth->h_proto = htons(ETH_P_IPV6);
 	} else {
@@ -470,7 +470,7 @@ void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 		put_unaligned(np->remote_ip.ip, &(iph->daddr));
 		iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);
 
-		eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
+		eth = skb_push(skb, ETH_HLEN);
 		skb_reset_mac_header(skb);
 		skb->protocol = eth->h_proto = htons(ETH_P_IP);
 	}
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index b8bcf9021329..2dd42c5b0366 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -2675,7 +2675,7 @@ static int process_ipsec(struct pktgen_dev *pkt_dev,
 				goto err;
 			}
 			/* restore ll */
-			eth = (struct ethhdr *)skb_push(skb, ETH_HLEN);
+			eth = skb_push(skb, ETH_HLEN);
 			memcpy(eth, pkt_dev->hh, 2 * ETH_ALEN);
 			eth->h_proto = protocol;
 
@@ -2844,7 +2844,7 @@ static struct sk_buff *fill_packet_ipv4(struct net_device *odev,
 	skb_reserve(skb, 16);
 
 	/*  Reserve for ethernet and IP header  */
-	eth = (__u8 *) skb_push(skb, 14);
+	eth = skb_push(skb, 14);
 	mpls = skb_put(skb, pkt_dev->nr_labels * sizeof(__u32));
 	if (pkt_dev->nr_labels)
 		mpls_push(mpls, pkt_dev);
@@ -2972,7 +2972,7 @@ static struct sk_buff *fill_packet_ipv6(struct net_device *odev,
 	skb_reserve(skb, 16);
 
 	/*  Reserve for ethernet and IP header  */
-	eth = (__u8 *) skb_push(skb, 14);
+	eth = skb_push(skb, 14);
 	mpls = skb_put(skb, pkt_dev->nr_labels * sizeof(__u32));
 	if (pkt_dev->nr_labels)
 		mpls_push(mpls, pkt_dev);
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 9a1639f7d61a..f75897a33fa4 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1461,7 +1461,7 @@ EXPORT_SYMBOL(skb_put);
  *	start. If this would exceed the total buffer headroom the kernel will
  *	panic. A pointer to the first byte of the extra data is returned.
  */
-unsigned char *skb_push(struct sk_buff *skb, unsigned int len)
+void *skb_push(struct sk_buff *skb, unsigned int len)
 {
 	skb->data -= len;
 	skb->len  += len;