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>

126 files changed, 204 insertions, 234 deletions

diff --git a/drivers/atm/solos-pci.c b/drivers/atm/solos-pci.c
index 4fc99ae1c534..c8f2ca6d8b29 100644
--- a/drivers/atm/solos-pci.c
+++ b/drivers/atm/solos-pci.c
@@ -1174,7 +1174,7 @@ static int psend(struct atm_vcc *vcc, struct sk_buff *skb)
 		}
 	}
 
-	header = (void *)skb_push(skb, sizeof(*header));
+	header = skb_push(skb, sizeof(*header));
 
 	/* This does _not_ include the size of the header */
 	header->size = cpu_to_le16(pktlen);
diff --git a/drivers/bluetooth/bpa10x.c b/drivers/bluetooth/bpa10x.c
index a9932fe57d92..48d10cb5c9a1 100644
--- a/drivers/bluetooth/bpa10x.c
+++ b/drivers/bluetooth/bpa10x.c
@@ -297,7 +297,7 @@ static int bpa10x_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
 		return -ENOMEM;
 
 	/* Prepend skb with frame type */
-	*skb_push(skb, 1) = hci_skb_pkt_type(skb);
+	*(u8 *)skb_push(skb, 1) = hci_skb_pkt_type(skb);
 
 	switch (hci_skb_pkt_type(skb)) {
 	case HCI_COMMAND_PKT:
diff --git a/drivers/firewire/net.c b/drivers/firewire/net.c
index d5040bbd34e8..242359c2d1f1 100644
--- a/drivers/firewire/net.c
+++ b/drivers/firewire/net.c
@@ -219,7 +219,7 @@ static int fwnet_header_create(struct sk_buff *skb, struct net_device *net,
 {
 	struct fwnet_header *h;
 
-	h = (struct fwnet_header *)skb_push(skb, sizeof(*h));
+	h = skb_push(skb, sizeof(*h));
 	put_unaligned_be16(type, &h->h_proto);
 
 	if (net->flags & (IFF_LOOPBACK | IFF_NOARP)) {
@@ -961,16 +961,14 @@ static int fwnet_send_packet(struct fwnet_packet_task *ptask)
 	tx_len = ptask->max_payload;
 	switch (fwnet_get_hdr_lf(&ptask->hdr)) {
 	case RFC2374_HDR_UNFRAG:
-		bufhdr = (struct rfc2734_header *)
-				skb_push(ptask->skb, RFC2374_UNFRAG_HDR_SIZE);
+		bufhdr = skb_push(ptask->skb, RFC2374_UNFRAG_HDR_SIZE);
 		put_unaligned_be32(ptask->hdr.w0, &bufhdr->w0);
 		break;
 
 	case RFC2374_HDR_FIRSTFRAG:
 	case RFC2374_HDR_INTFRAG:
 	case RFC2374_HDR_LASTFRAG:
-		bufhdr = (struct rfc2734_header *)
-				skb_push(ptask->skb, RFC2374_FRAG_HDR_SIZE);
+		bufhdr = skb_push(ptask->skb, RFC2374_FRAG_HDR_SIZE);
 		put_unaligned_be32(ptask->hdr.w0, &bufhdr->w0);
 		put_unaligned_be32(ptask->hdr.w1, &bufhdr->w1);
 		break;
diff --git a/drivers/infiniband/hw/cxgb3/iwch_cm.c b/drivers/infiniband/hw/cxgb3/iwch_cm.c
index 9ae518c01bc2..86975370a4c0 100644
--- a/drivers/infiniband/hw/cxgb3/iwch_cm.c
+++ b/drivers/infiniband/hw/cxgb3/iwch_cm.c
@@ -513,7 +513,7 @@ static void send_mpa_req(struct iwch_ep *ep, struct sk_buff *skb)
 	set_arp_failure_handler(skb, arp_failure_discard);
 	skb_reset_transport_header(skb);
 	len = skb->len;</