Patch "USB: serial: ftdi_sio: clean up receive processing" has been added to the 4.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    USB: serial: ftdi_sio: clean up receive processing

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-serial-ftdi_sio-clean-up-receive-processing.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 7522c33a9c81a0a29feb4c67d84d589342007637
Author: Johan Hovold <johan@xxxxxxxxxx>
Date:   Wed Jul 8 14:49:52 2020 +0200

    USB: serial: ftdi_sio: clean up receive processing
    
    [ Upstream commit ce054039ba5e47b75a3be02a00274e52b06a6456 ]
    
    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@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 4b9404f99c010..0afea511eb376 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -2054,7 +2054,6 @@ 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;
 
@@ -2097,8 +2096,7 @@ 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 */
 
 	/*
@@ -2127,19 +2125,20 @@ 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)