Commit 87108bc9 authored Jan 09, 2016 by Peter Hurley Committed by Greg Kroah-Hartman Jan 28, 2016

tty: n_tty: fix SIGIO for output



According to fcntl(2), "a SIGIO signal is sent whenever input
or output becomes possible on that file descriptor", i.e.
after the output buffer was full and now has space for new data.
But in fact SIGIO is sent after every write.

n_tty_write() should set TTY_DO_WRITE_WAKEUP only when
not all data could be written to the buffer.

[pjh: Also fixes missed SIGIO if amt written just happens to be
[     amount still to write

Signed-off-by: Johannes Stezenbach <js@sig21.net>
[pjh: minor patch edits and re-submit]

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent ffb91a45

drivers/tty/n_tty.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2361,7 +2361,7 @@ static ssize_t n_tty_write(struct tty_struct tty, struct file file,
		}
		break_out:
		remove_wait_queue(&tty->write_wait, &wait);
		if (b - buf != nr && tty->fasync)
		if (nr && tty->fasync)
		set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
		up_read(&tty->termios_rwsem);
		return (b - buf) ? b - buf : retval;

Admin message