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>

3 files changed, 4 insertions, 4 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 53b00bb52095..70e9d2ca8bbe 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -273,7 +273,7 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local,
 	if (!(has_fcs && ieee80211_hw_check(&local->hw, RX_INCLUDES_FCS)))
 		mpdulen += FCS_LEN;
 
-	rthdr = (struct ieee80211_radiotap_header *)skb_push(skb, rtap_len);
+	rthdr = skb_push(skb, rtap_len);
 	memset(rthdr, 0, rtap_len - rtap.len - rtap.pad);
 	it_present = &rthdr->it_present;
 
diff --git a/net/mac80211/status.c b/net/mac80211/status.c
index a9fa6ee57e8f..da7427a41529 100644
--- a/net/mac80211/status.c
+++ b/net/mac80211/status.c
@@ -288,7 +288,7 @@ ieee80211_add_tx_radiotap_header(struct ieee80211_local *local,
 	unsigned char *pos;
 	u16 txflags;
 
-	rthdr = (struct ieee80211_radiotap_header *) skb_push(skb, rtap_len);
+	rthdr = skb_push(skb, rtap_len);
 
 	memset(rthdr, 0, rtap_len);
 	rthdr->it_len = cpu_to_le16(rtap_len);
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);