mISDN: use memchr_inv

Use memchr_inv to check if the data contains all same bytes.  It is
faster than looping for each byte.
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: netdev@vger.kernel.org
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/isdn/mISDN/l1oip_core.c

@@ -1112,7 +1112,7 @@ handle_bmsg(struct mISDNchannel *ch, struct sk_buff *skb)
 	struct l1oip			*hc = bch->hw;
 	int			ret = -EINVAL;
 	struct mISDNhead	*hh = mISDN_HEAD_P(skb);
-	int			l, ll, i;
+	int			l, ll;
 	unsigned char		*p;
 
 	switch (hh->prim) {
@@ -1128,13 +1128,8 @@ handle_bmsg(struct mISDNchannel *ch, struct sk_buff *skb)
 			break;
 		}
 		/* check for AIS / ulaw-silence */
-		p = skb->data;
 		l = skb->len;
-		for (i = 0; i < l; i++) {
-			if (*p++ != 0xff)
-				break;
-		}
-		if (i == l) {
+		if (!memchr_inv(skb->data, 0xff, l)) {
 			if (debug & DEBUG_L1OIP_MSG)
 				printk(KERN_DEBUG "%s: got AIS, not sending, "
 					"but counting\n", __func__);
@@ -1144,13 +1139,8 @@ handle_bmsg(struct mISDNchannel *ch, struct sk_buff *skb)
 			return 0;
 		}
 		/* check for silence */
-		p = skb->data;
 		l = skb->len;
-		for (i = 0; i < l; i++) {
-			if (*p++ != 0x2a)
-				break;
-		}
-		if (i == l) {
+		if (!memchr_inv(skb->data, 0x2a, l)) {
 			if (debug & DEBUG_L1OIP_MSG)
 				printk(KERN_DEBUG "%s: got silence, not sending"
 					", but counting\n", __func__);