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/digital_technology.c b/net/nfc/digital_technology.c
index fae6d31b377c..492204e440ec 100644
--- a/net/nfc/digital_technology.c
+++ b/net/nfc/digital_technology.c
@@ -828,7 +828,7 @@ int digital_in_send_sensf_req(struct nfc_digital_dev *ddev, u8 rf_tech)
 	sensf_req->rc = 0;
 	sensf_req->tsn = 0;
 
-	*skb_push(skb, 1) = size + 1;
+	*(u8 *)skb_push(skb, 1) = size + 1;
 
 	if (!DIGITAL_DRV_CAPS_IN_CRC(ddev))
 		digital_skb_add_crc_f(skb);
@@ -1161,7 +1161,7 @@ static int digital_tg_send_sensf_res(struct nfc_digital_dev *ddev,
 		break;
 	}
 
-	*skb_push(skb, sizeof(u8)) = size + 1;
+	*(u8 *)skb_push(skb, sizeof(u8)) = size + 1;
 
 	if (!DIGITAL_DRV_CAPS_TG_CRC(ddev))
 		digital_skb_add_crc_f(skb);