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n_tty: Fix stuck write wakeup 

If signal-driven i/o is disabled while write wakeup is pending (ie.,
n_tty_write() has set TTY_DO_WRITE_WAKEUP but then signal-driven i/o
is disabled), the TTY_DO_WRITE_WAKEUP bit will never be cleared and
will cause tty_wakeup() to always call n_tty_write_wakeup.

Unconditionally clear the write wakeup, and since kill_fasync()
already checks if the fasync ptr is null, call kill_fasync()
unconditionally as well.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Hurley 2016-01-09 21:45:12 -08:00 committed by Greg Kroah-Hartman
parent a8f3a29718
commit 7bccc36544
1 changed files with 2 additions and 2 deletions
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4
drivers/tty/n_tty.c
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@ -228,8 +228,8 @@ static ssize_t chars_in_buffer(struct tty_struct *tty)
static void n_tty_write_wakeup(struct tty_struct *tty)
{
if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
}
static void n_tty_check_throttle(struct tty_struct *tty)