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authorPeter Hurley <peter@hurleysoftware.com>2014-09-10 23:06:30 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-09-24 08:19:35 +0400
commitd7a855bd6ab25d10d5e3b6aeb53d9c57fa17b808 (patch)
treeb66d63feabc17c8b53fe7c105ea7d9c2d618beb1 /include/linux/tty.h
parent938f7e13b55a76ad98964509f6d13bbcf852e617 (diff)
downloadlinux-d7a855bd6ab25d10d5e3b6aeb53d9c57fa17b808.tar.xz
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>
Diffstat (limited to 'include/linux/tty.h')
-rw-r--r--include/linux/tty.h5
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 84132942902a..4cfd4a82fc31 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -261,7 +261,10 @@ struct tty_struct {
unsigned long flags;
int count;
struct winsize winsize; /* winsize_mutex */
- unsigned char stopped:1, hw_stopped:1, flow_stopped:1, packet:1;
+ int stopped;
+ int flow_stopped;
+ int hw_stopped;
+ int packet;
unsigned char ctrl_status; /* ctrl_lock */
unsigned int receive_room; /* Bytes free for queue */
int flow_change;