From 7bccc36544a8b4a7d768f8ccdd6001a52872aca9 Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Sat, 9 Jan 2016 21:45:12 -0800 Subject: [PATCH] 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 Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_tty.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index a93e4c7..086fd99 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -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) -- 2.7.4