[Patch] Fix a race condition in pty.c

[Zou, Nanhai]

 <<pty_close-race-fix.patch>> There is a race condition int pty.c 
when pty_close wakes up waiter on its pair device before set
TTY_OTHER_CLOSED flag.

It is possible on SMP or preempt kernel, waiter wakes up too early that
it will not get TTY_OTHER_CLOSED flag then fall into sleep again.

Lu hong jiu report this bug will hang some expect scripts on SMP
machines.

Signed-off-by:	Zou Nan hai <Nanhai.zou@xxxxxxxxx>

Zou Nan hai

Attachment: pty_close-race-fix.patch
Description: pty_close-race-fix.patch