From 87108bc9870ae86ca4fcc05115a134af7a0f4e96 Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Sat, 9 Jan 2016 21:45:14 -0800 Subject: [PATCH] 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 [pjh: minor patch edits and re-submit] Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_tty.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 5ae661cd236e..fad365aa1f5c 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -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; -- 2.30.2