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, 2 insertions, 2 deletions

diff --git a/net/nfc/nci/spi.c b/net/nfc/nci/spi.c
index a502a334918a..3b4512731a2f 100644
--- a/net/nfc/nci/spi.c
+++ b/net/nfc/nci/spi.c
@@ -238,8 +238,8 @@ static struct sk_buff *__nci_spi_read(struct nci_spi *nspi)
 		goto receive_error;
 
 	if (nspi->acknowledge_mode == NCI_SPI_CRC_ENABLED) {
-		*skb_push(skb, 1) = resp_hdr[1];
-		*skb_push(skb, 1) = resp_hdr[0];
+		*(u8 *)skb_push(skb, 1) = resp_hdr[1];
+		*(u8 *)skb_push(skb, 1) = resp_hdr[0];
 	}
 
 	return skb;