From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932263AbcAJFqT (ORCPT ); Sun, 10 Jan 2016 00:46:19 -0500 Received: from mail-pa0-f51.google.com ([209.85.220.51]:36046 "EHLO mail-pa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752888AbcAJFp2 (ORCPT ); Sun, 10 Jan 2016 00:45:28 -0500 From: Peter Hurley To: Greg Kroah-Hartman Cc: Jiri Slaby , linux-kernel@vger.kernel.org, Peter Hurley , Johannes Stezenbach Subject: [PATCH v2 7/7] tty: n_tty: fix SIGIO for output Date: Sat, 9 Jan 2016 21:45:14 -0800 Message-Id: <1452404714-9295-8-git-send-email-peter@hurleysoftware.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1452404714-9295-1-git-send-email-peter@hurleysoftware.com> References: <1449958599-5533-1-git-send-email-peter@hurleysoftware.com> <1452404714-9295-1-git-send-email-peter@hurleysoftware.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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 5ae661c..fad365a 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; -- 2.7.0