watchdog: ziirave_wdt: Check packet length only once

We don't need to check for packet length more than once, so drop the
extra check in ziirave_firm_upload(). While at it move the check at
the very start of __ziirave_firm_write_pkt(), as to not waste any time
preparing a packet we'll never use.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Chris Healy <cphealy@gmail.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Rick Ramstetter <rick@anteaterllc.com>
Cc: linux-watchdog@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20190812200906.31344-8-andrew.smirnov@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/ziirave_wdt.c

@@ -253,6 +253,13 @@ static int __ziirave_firm_write_pkt(struct watchdog_device *wdd,
 	u8 i, checksum = 0, packet[ZIIRAVE_FIRM_PKT_TOTAL_SIZE];
 	int ret;
 
+	/* Check max data size */
+	if (len > ZIIRAVE_FIRM_PKT_DATA_SIZE) {
+		dev_err(&client->dev, "Firmware packet too long (%d)\n",
+			len);
+		return -EMSGSIZE;
+	}
+
 	memset(packet, 0, ARRAY_SIZE(packet));
 
 	/* Packet length */
@@ -261,9 +268,6 @@ static int __ziirave_firm_write_pkt(struct watchdog_device *wdd,
 	packet[1] = addr16 & 0xff;
 	packet[2] = (addr16 & 0xff00) >> 8;
 
-	/* Packet data */
-	if (len > ZIIRAVE_FIRM_PKT_DATA_SIZE)
-		return -EMSGSIZE;
 	memcpy(packet + 3, data, len);
 
 	/* Packet checksum */
@@ -382,13 +386,6 @@ static int ziirave_firm_upload(struct watchdog_device *wdd,
 		if (!be16_to_cpu(rec->len))
 			break;
 
-		/* Check max data size */
-		if (be16_to_cpu(rec->len) > ZIIRAVE_FIRM_PKT_DATA_SIZE) {
-			dev_err(&client->dev, "Firmware packet too long (%d)\n",
-				be16_to_cpu(rec->len));
-			return -EMSGSIZE;
-		}
-
 		ret = ziirave_firm_write_pkt(wdd, be32_to_cpu(rec->addr),
 					     rec->data, be16_to_cpu(rec->len));
 		if (ret)