linux-kernel - [PATCH] tty: Fix SIGTTOU not sent with tcflush()

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Message-Id: <1380154395-4232-1-git-send-email-peter@hurleysoftware.com>
Date:	Wed, 25 Sep 2013 20:13:04 -0400
From:	Peter Hurley <peter@...leysoftware.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	Jiri Slaby <jslaby@...e.cz>, Oleg Nesterov <oleg@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	codonell <codonell@...hat.com>, Eduard Benes <ebenes@...hat.com>,
	Karel Srot <ksrot@...hat.com>,
	Matt Newsome <mnewsome@...hat.com>,
	linux-kernel@...r.kernel.org,
	Peter Hurley <peter@...leysoftware.com>, stable@...r.kernel.org
Subject: [PATCH] tty: Fix SIGTTOU not sent with tcflush()

Commit 'e7f3880cd9b98c5bf9391ae7acdec82b75403776'
  tty: Fix recursive deadlock in tty_perform_flush()
introduced a regression where tcflush() does not generate
SIGTTOU for background process groups.

Make sure ioctl(TCFLSH) calls tty_check_change() when
invoked from the line discipline.

Cc: stable@...r.kernel.org # v3.10+
Reported-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Peter Hurley <peter@...leysoftware.com>
---
 drivers/tty/tty_ioctl.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index 3500d41..088b4ca 100644
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -1201,6 +1201,9 @@ int n_tty_ioctl_helper(struct tty_struct *tty, struct file *file,
 		}
 		return 0;
 	case TCFLSH:
+		retval = tty_check_change(tty);
+		if (retval)
+			return retval;
 		return __tty_perform_flush(tty, arg);
 	default:
 		/* Try the mode commands */
-- 
1.8.1.2

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