From: Peter Hurley <peter@hurleysoftware.com>
Date: Wed, 10 Sep 2014 19:06:30 +0000 (-0400)
Subject: tty: Convert tty_struct bitfield to ints
X-Git-Tag: fixes-for-v3.18-merge-window~14^2~30
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d7a855bd6ab25d10d5e3b6aeb53d9c57fa17b808;p=pandora-kernel.git

tty: Convert tty_struct bitfield to ints

The stopped, hw_stopped, flow_stopped and packet bits are smp-unsafe
and interrupt-unsafe. For example,

CPU 0                         | CPU 1
                              |
tty->flow_stopped = 1         | tty->hw_stopped = 0

One of these updates will be corrupted, as the bitwise operation
on the bitfield is non-atomic.

Ensure each flag has a separate memory location, so concurrent
updates do not corrupt orthogonal states. Because DEC Alpha EV4 and EV5
cpus (from 1995) perform RMW on smaller-than-machine-word storage,
"separate memory location" must be int instead of byte.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

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