From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934719AbZGQPiX (ORCPT ); Fri, 17 Jul 2009 11:38:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934703AbZGQPiX (ORCPT ); Fri, 17 Jul 2009 11:38:23 -0400 Received: from mx10.kentrox.com ([192.228.33.31]:41217 "EHLO smtp.kentrox.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S934687AbZGQPiW (ORCPT ); Fri, 17 Jul 2009 11:38:22 -0400 X-Greylist: delayed 1826 seconds by postgrey-1.27 at vger.kernel.org; Fri, 17 Jul 2009 11:38:22 EDT From: Jeff Harris To: alan@linux.intel.com, vapier@gentoo.org, adobriyan@gmail.com Cc: linux-kernel@vger.kernel.org, Jeff Harris Subject: [PATCH] tty: Fix tcdrain hang due to tty chars_in_buffer errors Date: Fri, 17 Jul 2009 11:07:54 -0400 Message-Id: <1247843274-7462-1-git-send-email-jeff_harris@kentrox.com> X-Mailer: git-send-email 1.5.5.1 X-OriginalArrivalTime: 17 Jul 2009 15:07:54.0178 (UTC) FILETIME=[5C2BEA20:01CA06F0] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If a tty driver's chars_in_buffer callback reports an error, the wait loop in tty_wait_until_sent may never exit until its timeout. A tty device disconnection will hangup the tty causing the tty_wait_until_sent loop to wake-up, but if the subsequent call to chars_in_buffer reports an error instead of zero, the loop will go back to sleep instead of exiting. A process calling tcdrain will block indefinitely if it calls tcdrain when the device is disconnected. Signed-off-by: Jeff Harris --- drivers/char/tty_ioctl.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/char/tty_ioctl.c b/drivers/char/tty_ioctl.c index ad6ba4e..306d52e 100644 --- a/drivers/char/tty_ioctl.c +++ b/drivers/char/tty_ioctl.c @@ -156,7 +156,7 @@ void tty_wait_until_sent(struct tty_struct *tty, long timeout) if (!timeout) timeout = MAX_SCHEDULE_TIMEOUT; if (wait_event_interruptible_timeout(tty->write_wait, - !tty_chars_in_buffer(tty), timeout) >= 0) { + tty_chars_in_buffer(tty) <= 0, timeout) >= 0) { if (tty->ops->wait_until_sent) tty->ops->wait_until_sent(tty, timeout); } @@ -332,7 +332,7 @@ void tty_termios_encode_baud_rate(struct ktermios *termios, int iclose = ibaud/50, oclose = obaud/50; int ibinput = 0; - if (obaud == 0) /* CD dropped */ + if (obaud == 0) /* CD dropped */ ibaud = 0; /* Clear ibaud to be sure */ termios->c_ispeed = ibaud; -- 1.5.5.1