[PATCH] zd1211rw: Optimized handling of zero length entries in length info

There are a high number of split USB transactions, which contain
only one packet but have a length info field. This patch optimizes
this code by stopping parsing the length info structure if a zero
length field is encountered.
Signed-off-by: NUlrich Kunitz <kune@deine-taler.de>
Signed-off-by: NDaniel Drake <dsd@gentoo.org>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/zd1211rw/zd_usb.c

@@ -593,6 +593,8 @@ static void handle_rx_packet(struct zd_usb *usb, const u8 *buffer,
 		unsigned int l, k, n;
 		for (i = 0, l = 0;; i++) {
 			k = le16_to_cpu(get_unaligned(&length_info->length[i]));
+			if (k == 0)
+				return;
 			n = l+k;
 			if (n > length)
 				return;