Commit 7bccc365 authored Jan 09, 2016 by Peter Hurley Committed by Greg Kroah-Hartman Jan 28, 2016

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>

parent a8f3a297

drivers/tty/n_tty.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -228,7 +228,7 @@ 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))
		clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
		kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
		}

Admin message