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/drivers/nfc/microread/microread.c b/drivers/nfc/microread/microread.c
index 9d0dd1be0923..38a979eacc29 100644
--- a/drivers/nfc/microread/microread.c
+++ b/drivers/nfc/microread/microread.c
@@ -419,7 +419,7 @@ static int microread_im_transceive(struct nfc_hci_dev *hdev,
 	pr_info("data exchange to gate 0x%x\n", target->hci_reader_gate);
 
 	if (target->hci_reader_gate == MICROREAD_GATE_ID_P2P_INITIATOR) {
-		*skb_push(skb, 1) = 0;
+		*(u8 *)skb_push(skb, 1) = 0;
 
 		return nfc_hci_send_event(hdev, target->hci_reader_gate,
 				     MICROREAD_EVT_P2P_INITIATOR_EXCHANGE_TO_RF,
@@ -453,7 +453,7 @@ static int microread_im_transceive(struct nfc_hci_dev *hdev,
 		return 1;
 	}
 
-	*skb_push(skb, 1) = control_bits;
+	*(u8 *)skb_push(skb, 1) = control_bits;
 
 	info->async_cb_type = MICROREAD_CB_TYPE_READER_ALL;
 	info->async_cb = cb;