From: Peter Hurley <peter@hurleysoftware.com>
To: Alan Cox <alan@linux.intel.com>, Jiri Slaby <jslaby@suse.cz>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
Peter Hurley <peter@hurleysoftware.com>
Subject: [PATCH -next 4/9] tty: Refactor wait for ldisc refs out of tty_ldisc_hangup()
Date: Tue, 4 Dec 2012 02:07:40 -0500 [thread overview]
Message-ID: <1354604865-10278-5-git-send-email-peter@hurleysoftware.com> (raw)
In-Reply-To: <1354604865-10278-1-git-send-email-peter@hurleysoftware.com>
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 <peter@hurleysoftware.com>
---
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
next prev parent reply other threads:[~2012-12-04 7:07 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-04 7:07 [PATCH -next 0/9] tty: Fix buffer work access-after-free Peter Hurley
2012-12-04 7:07 ` [PATCH -next 1/9] tty: WARN if buffer work racing with tty free Peter Hurley
2012-12-04 7:07 ` [PATCH -next 2/9] tty: Add diagnostic for halted line discipline Peter Hurley
2012-12-04 7:07 ` [PATCH -next 3/9] tty: Don't reschedule buffer work while closing Peter Hurley
2012-12-04 7:07 ` Peter Hurley [this message]
2012-12-04 7:07 ` [PATCH -next 5/9] tty: Remove unnecessary re-test of ldisc ref count Peter Hurley
2012-12-04 7:07 ` [PATCH -next 6/9] tty: Fix ldisc halt sequence on hangup Peter Hurley
2012-12-04 7:07 ` [PATCH -next 7/9] tty: Strengthen no-subsequent-use guarantee of tty_ldisc_halt() Peter Hurley
2012-12-04 7:07 ` [PATCH -next 8/9] tty: Remove unnecessary buffer work flush Peter Hurley
2012-12-04 7:07 ` [PATCH -next 9/9] tty: Halt both ldiscs concurrently Peter Hurley
2012-12-04 7:40 ` [PATCH -next 0/9] tty: Fix buffer work access-after-free Ilya Zykov
2012-12-04 8:54 ` Alan Cox
2012-12-04 13:58 ` Peter Hurley
2012-12-04 14:30 ` Alan Cox
2012-12-04 9:38 ` Jiri Slaby
2012-12-07 0:57 ` Peter Hurley
2012-12-10 19:00 ` Ilya Zykov
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