From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756935Ab2LNSXb (ORCPT ); Fri, 14 Dec 2012 13:23:31 -0500 Received: from mailout39.mail01.mtsvc.net ([216.70.64.83]:43411 "EHLO n12.mail01.mtsvc.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756904Ab2LNSX2 (ORCPT ); Fri, 14 Dec 2012 13:23:28 -0500 From: Peter Hurley To: Alan Cox , Jiri Slaby Cc: linux-serial@vger.kernel.org, Greg Kroah-Hartman , Ilya Zykov , Sasha Levin , linux-kernel@vger.kernel.org, Peter Hurley Subject: [PATCH v2 06/11] tty: Refactor wait for ldisc refs out of tty_ldisc_hangup() Date: Fri, 14 Dec 2012 13:22:45 -0500 Message-Id: <1355509370-5883-7-git-send-email-peter@hurleysoftware.com> X-Mailer: git-send-email 1.8.0.1 In-Reply-To: <1355509370-5883-1-git-send-email-peter@hurleysoftware.com> References: <1355509370-5883-1-git-send-email-peter@hurleysoftware.com> X-Authenticated-User: 125194 peter@hurleysoftware.com X-MT-ID: 8fa290c2a27252aacf65dbc4a42f3ce3735fb2a4 X-MT-INTERNAL-ID: 8fa290c2a27252aacf65dbc4a42f3ce3735fb2a4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Refactor tty_ldisc_hangup() to extract standalone function, tty_ldisc_hangup_wait_idle(), to wait for ldisc references to be released. Signed-off-by: Peter Hurley --- drivers/tty/tty_ldisc.c | 54 ++++++++++++++++++++++++++++++++----------------- 1 file changed, 36 insertions(+), 18 deletions(-) diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c index f986bb0..6c1d8aa 100644 --- a/drivers/tty/tty_ldisc.c +++ b/drivers/tty/tty_ldisc.c @@ -549,6 +549,41 @@ static int tty_ldisc_halt(struct tty_struct *tty) } /** + * tty_ldisc_hangup_wait_idle - wait for the ldisc to become idle + * @tty: tty to wait for + * + * Wait for the line discipline to become idle. The discipline must + * have been halted for this to guarantee it remains idle. + * + * Caller must hold legacy and ->ldisc_mutex. + */ +static bool tty_ldisc_hangup_wait_idle(struct tty_struct *tty) +{ + while (tty->ldisc) { /* Not yet closed */ + if (atomic_read(&tty->ldisc->users) != 1) { + char cur_n[TASK_COMM_LEN], tty_n[64]; + long timeout = 3 * HZ; + tty_unlock(tty); + + while (tty_ldisc_wait_idle(tty, timeout) == -EBUSY) { + timeout = MAX_SCHEDULE_TIMEOUT; + printk_ratelimited(KERN_WARNING + "%s: waiting (%s) for %s took too long, but we keep waiting...\n", + __func__, get_task_comm(cur_n, current), + tty_name(tty, tty_n)); + } + /* must reacquire both locks and preserve lock order */ + mutex_unlock(&tty->ldisc_mutex); + tty_lock(tty); + mutex_lock(&tty->ldisc_mutex); + continue; + } + break; + } + return !!(tty->ldisc); +} + +/** * tty_set_ldisc - set line discipline * @tty: the terminal to set * @ldisc: the line discipline @@ -824,7 +859,6 @@ void tty_ldisc_hangup(struct tty_struct *tty) cancel_work_sync(&tty->port->buf.work); set_bit(TTY_LDISC_HALTED, &tty->flags); mutex_unlock(&tty->ldisc_mutex); -retry: tty_lock(tty); mutex_lock(&tty->ldisc_mutex); @@ -832,23 +866,7 @@ retry: reopen it. We could defer this to the next open but it means auditing a lot of other paths so this is a FIXME */ - if (tty->ldisc) { /* Not yet closed */ - if (atomic_read(&tty->ldisc->users) != 1) { - char cur_n[TASK_COMM_LEN], tty_n[64]; - long timeout = 3 * HZ; - tty_unlock(tty); - - while (tty_ldisc_wait_idle(tty, timeout) == -EBUSY) { - timeout = MAX_SCHEDULE_TIMEOUT; - printk_ratelimited(KERN_WARNING - "%s: waiting (%s) for %s took too long, but we keep waiting...\n", - __func__, get_task_comm(cur_n, current), - tty_name(tty, tty_n)); - } - mutex_unlock(&tty->ldisc_mutex); - goto retry; - } - + if (tty_ldisc_hangup_wait_idle(tty)) { if (reset == 0) { if (!tty_ldisc_reinit(tty, tty->termios.c_line)) -- 1.8.0.1