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/mac80211/tx.c b/net/mac80211/tx.c
index ec5a9a72797e..8858f4f185e9 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -2708,7 +2708,7 @@ static struct sk_buff *ieee80211_build_hdr(struct ieee80211_sub_if_data *sdata,
 	if (ieee80211_is_data_qos(fc)) {
 		__le16 *qos_control;
 
-		qos_control = (__le16 *) skb_push(skb, 2);
+		qos_control = skb_push(skb, 2);
 		memcpy(skb_push(skb, hdrlen - 2), &hdr, hdrlen - 2);
 		/*
 		 * Maybe we could actually set some fields here, for now just
@@ -3347,7 +3347,7 @@ static bool ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
 	}
 
 	memcpy(&eth, skb->data, ETH_HLEN - 2);
-	hdr = (void *)skb_push(skb, extra_head);
+	hdr = skb_push(skb, extra_head);
 	memcpy(skb->data, fast_tx->hdr, fast_tx->hdr_len);
 	memcpy(skb->data + fast_tx->da_offs, eth.h_dest, ETH_ALEN);
 	memcpy(skb->data + fast_tx->sa_offs, eth.h_source, ETH_ALEN);