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, 4 insertions, 4 deletions

diff --git a/net/802/fc.c b/net/802/fc.c
index 1bb496ea997e..058a9f708918 100644
--- a/net/802/fc.c
+++ b/net/802/fc.c
@@ -49,7 +49,7 @@ static int fc_header(struct sk_buff *skb, struct net_device *dev,
                 struct fcllc *fcllc;
 
                 hdr_len = sizeof(struct fch_hdr) + sizeof(struct fcllc);
-                fch = (struct fch_hdr *)skb_push(skb, hdr_len);
+                fch = skb_push(skb, hdr_len);
                 fcllc = (struct fcllc *)(fch+1);
                 fcllc->dsap = fcllc->ssap = EXTENDED_SAP;
                 fcllc->llc = UI_CMD;
@@ -59,7 +59,7 @@ static int fc_header(struct sk_buff *skb, struct net_device *dev,
         else
         {
                 hdr_len = sizeof(struct fch_hdr);
-                fch = (struct fch_hdr *)skb_push(skb, hdr_len);
+                fch = skb_push(skb, hdr_len);
         }
 
         if(saddr)
diff --git a/net/802/fddi.c b/net/802/fddi.c
index 6356623fc238..90f1416567a1 100644
--- a/net/802/fddi.c
+++ b/net/802/fddi.c
@@ -58,7 +58,7 @@ static int fddi_header(struct sk_buff *skb, struct net_device *dev,
 
         if(type != ETH_P_IP && type != ETH_P_IPV6 && type != ETH_P_ARP)
                 hl=FDDI_K_8022_HLEN-3;
-        fddi = (struct fddihdr *)skb_push(skb, hl);
+        fddi = skb_push(skb, hl);
         fddi->fc                         = FDDI_FC_K_ASYNC_LLC_DEF;
         if(type == ETH_P_IP || type == ETH_P_IPV6 || type == ETH_P_ARP)
         {
diff --git a/net/802/hippi.c b/net/802/hippi.c
index 4460606e9c36..690308b9b94a 100644
--- a/net/802/hippi.c
+++ b/net/802/hippi.c
@@ -47,7 +47,7 @@ static int hippi_header(struct sk_buff *skb, struct net_device *dev,
                         unsigned short type,
                         const void *daddr, const void *saddr, unsigned int len)
 {
-        struct hippi_hdr *hip = (struct hippi_hdr *)skb_push(skb, HIPPI_HLEN);
+        struct hippi_hdr *hip = skb_push(skb, HIPPI_HLEN);
         struct hippi_cb *hcb = (struct hippi_cb *) skb->cb;
 
         if (!len){