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>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/isdn/capi/capi.c b/drivers/isdn/capi/capi.c
index 96f586d34d2d..dde8f46bc254 100644
--- a/drivers/isdn/capi/capi.c
+++ b/drivers/isdn/capi/capi.c
@@ -1082,7 +1082,7 @@ static int capinc_tty_put_char(struct tty_struct *tty, unsigned char ch)
 	skb = mp->outskb;
 	if (skb) {
 		if (skb_tailroom(skb) > 0) {
-			*(u8 *)skb_put(skb, 1) = ch;
+			skb_put_u8(skb, ch);
 			goto unlock_out;
 		}
 		mp->outskb = NULL;
@@ -1094,7 +1094,7 @@ static int capinc_tty_put_char(struct tty_struct *tty, unsigned char ch)
 	skb = alloc_skb(CAPI_DATA_B3_REQ_LEN + CAPI_MAX_BLKSIZE, GFP_ATOMIC);
 	if (skb) {
 		skb_reserve(skb, CAPI_DATA_B3_REQ_LEN);
-		*(u8 *)skb_put(skb, 1) = ch;
+		skb_put_u8(skb, ch);
 		mp->outskb = skb;
 	} else {
 		printk(KERN_ERR "capinc_put_char: char %u lost\n", ch);