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| author | Peter Hurley <peter@hurleysoftware.com> | 2014-09-10 23:06:30 +0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-09-24 08:19:35 +0400 |
| commit | d7a855bd6ab25d10d5e3b6aeb53d9c57fa17b808 (patch) | |
| tree | b66d63feabc17c8b53fe7c105ea7d9c2d618beb1 /include/linux/tty.h | |
| parent | 938f7e13b55a76ad98964509f6d13bbcf852e617 (diff) | |
| download | linux-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.h | 5 |
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; |