From 765fd98acaf87df59fc8ff041ea7c9b574228d8e Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Wed, 8 Jul 2020 14:49:52 +0200
Subject: [PATCH] USB: serial: ftdi_sio: clean up receive processing

commit ce054039ba5e47b75a3be02a00274e52b06a6456 upstream.

Clean up receive processing by dropping the character pointer and
keeping the length argument unchanged throughout the function.

Also make it more apparent that sysrq processing can consume a
characters by adding an explicit continue.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 2587dcd3de68..13aaf0687367 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -2440,7 +2440,6 @@ static int ftdi_process_packet(struct usb_serial_port *port,
 		struct ftdi_private *priv, unsigned char *buf, int len)
 {
 	unsigned char status;
-	unsigned char *ch;
 	int i;
 	char flag;
 
@@ -2483,8 +2482,7 @@ static int ftdi_process_packet(struct usb_serial_port *port,
 	else
 		priv->transmit_empty = 0;
 
-	len -= 2;
-	if (!len)
+	if (len == 2)
 		return 0;	/* status only */
 
 	/*
@@ -2513,19 +2511,20 @@ static int ftdi_process_packet(struct usb_serial_port *port,
 		}
 	}
 
-	port->icount.rx += len;
-	ch = buf + 2;
+	port->icount.rx += len - 2;
 
 	if (port->port.console && port->sysrq) {
-		for (i = 0; i < len; i++, ch++) {
-			if (!usb_serial_handle_sysrq_char(port, *ch))
-				tty_insert_flip_char(&port->port, *ch, flag);
+		for (i = 2; i < len; i++) {
+			if (usb_serial_handle_sysrq_char(port, buf[i]))
+				continue;
+			tty_insert_flip_char(&port->port, buf[i], flag);
 		}
 	} else {
-		tty_insert_flip_string_fixed_flag(&port->port, ch, flag, len);
+		tty_insert_flip_string_fixed_flag(&port->port, buf + 2, flag,
+				len - 2);
 	}
 
-	return len;
+	return len - 2;
 }
 
 static void ftdi_process_read_urb(struct urb *urb)
-- 
2.27.0