Patch "USB: serial: ftdi_sio: fix setting latency for unprivileged users" has been added to the 4.4-stable tree

Patch "USB: serial: ftdi_sio: fix setting latency for unprivileged users" has been added to the 4.4-stable tree

[gregkh]

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

    USB: serial: ftdi_sio: fix setting latency for unprivileged users

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-fix-setting-latency-for-unprivileged-users.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@vger.kernel.org> know about it.


>From bb246681b3ed0967489a7401ad528c1aaa1a4c2e Mon Sep 17 00:00:00 2001
From: Anthony Mallet <anthony.mallet@laas.fr>
Date: Fri, 5 May 2017 17:30:16 +0200
Subject: USB: serial: ftdi_sio: fix setting latency for unprivileged users

From: Anthony Mallet <anthony.mallet@laas.fr>

commit bb246681b3ed0967489a7401ad528c1aaa1a4c2e upstream.

Commit 557aaa7ffab6 ("ft232: support the ASYNC_LOW_LATENCY
flag") enables unprivileged users to set the FTDI latency timer,
but there was a logic flaw that skipped sending the corresponding
USB control message to the device.

Specifically, the device latency timer would not be updated until next
open, something which was later also inadvertently broken by commit
c19db4c9e49a ("USB: ftdi_sio: set device latency timeout at port
probe").

A recent commit c6dce2626606 ("USB: serial: ftdi_sio: fix extreme
low-latency setting") disabled the low-latency mode by default so we now
need this fix to allow unprivileged users to again enable it.

Signed-off-by: Anthony Mallet <anthony.mallet@laas.fr>
[johan: amend commit message]
Fixes: 557aaa7ffab6 ("ft232: support the ASYNC_LOW_LATENCY flag")
Fixes: c19db4c9e49a ("USB: ftdi_sio: set device latency timeout at port probe").
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/serial/ftdi_sio.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1508,9 +1508,9 @@ static int set_serial_info(struct tty_st
 					(new_serial.flags & ASYNC_FLAGS));
 	priv->custom_divisor = new_serial.custom_divisor;
 
+check_and_exit:
 	write_latency_timer(port);
 
-check_and_exit:
 	if ((old_priv.flags & ASYNC_SPD_MASK) !=
 	     (priv->flags & ASYNC_SPD_MASK)) {
 		if ((priv->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)


Patches currently in stable-queue which might be from anthony.mallet@laas.fr are

queue-4.4/usb-serial-ftdi_sio-fix-setting-latency-for-unprivileged-users.patch