networking: add and use skb_put_u8()

Joe and Bjørn suggested that it'd be nicer to not have the
cast in the fairly common case of doing
	*(u8 *)skb_put(skb, 1) = c;

Add skb_put_u8() for this case, and use it across the code,
using the following spatch:

    @@
    expression SKB, C, S;
    typedef u8;
    identifier fn = {skb_put};
    fresh identifier fn2 = fn ## "_u8";
    @@
    - *(u8 *)fn(SKB, S) = C;
    + fn2(SKB, C);

Note that due to the "S", the spatch isn't perfect, it should
have checked that S is 1, but there's also places that use a
sizeof expression like sizeof(var) or sizeof(u8) etc. Turns
out that nobody ever did something like
	*(u8 *)skb_put(skb, 2) = c;

which would be wrong anyway since the second byte wouldn't be
initialized.

Suggested-by: Joe Perches <joe@perches.com>
Suggested-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 4 insertions, 4 deletions

diff --git a/drivers/nfc/microread/i2c.c b/drivers/nfc/microread/i2c.c
index 386cc61d95b9..b668b7b9a61e 100644
--- a/drivers/nfc/microread/i2c.c
+++ b/drivers/nfc/microread/i2c.c
@@ -75,7 +75,7 @@ static void microread_i2c_add_len_crc(struct sk_buff *skb)
 	for (i = 0; i < skb->len; i++)
 		crc = crc ^ skb->data[i];
 
-	*(u8 *)skb_put(skb, 1) = crc;
+	skb_put_u8(skb, crc);
 }
 
 static void microread_i2c_remove_len_crc(struct sk_buff *skb)
@@ -173,7 +173,7 @@ static int microread_i2c_read(struct microread_i2c_phy *phy,
 		goto flush;
 	}
 
-	*(u8 *)skb_put(*skb, 1) = len;
+	skb_put_u8(*skb, len);
 
 	r = i2c_master_recv(client, skb_put(*skb, len), len);
 	if (r != len) {
diff --git a/drivers/nfc/microread/microread.c b/drivers/nfc/microread/microread.c
index 38a979eacc29..e5d5d2d97409 100644
--- a/drivers/nfc/microread/microread.c
+++ b/drivers/nfc/microread/microread.c
@@ -441,8 +441,8 @@ static int microread_im_transceive(struct nfc_hci_dev *hdev,
 
 		crc = crc_ccitt(0xffff, skb->data, skb->len);
 		crc = ~crc;
-		*(u8 *)skb_put(skb, 1) = crc & 0xff;
-		*(u8 *)skb_put(skb, 1) = crc >> 8;
+		skb_put_u8(skb, crc & 0xff);
+		skb_put_u8(skb, crc >> 8);
 		break;
 	case MICROREAD_GATE_ID_MREAD_NFC_T3:
 		control_bits = 0xDB;