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authorPeter Hurley <peter@hurleysoftware.com>2014-11-05 12:13:07 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-11-05 18:50:43 -0800
commitfae76e9adfa450f4c2dd5773265eb3c811a9c484 (patch)
tree88f6086470fe19b2299568b24e4b27d8e3c608f7 /drivers/tty/tty_ldisc.c
parente80a10ee4de8f654cf34170da00f989470331da8 (diff)
downloadlinux-fae76e9adfa450f4c2dd5773265eb3c811a9c484.tar.bz2
tty: Fix hung task on pty hangup
When hanging up one end of a pty pair, there may be waiting readers/writers on the other end which may not exit, preventing tty_ldisc_lock_pair() from acquiring the other side's ldisc lock. Only acquire this side's ldisc lock; although this will no longer prevent the other side from writing new input, that input will not be processing until after the ldisc hangup is complete. Reported-by: Sasha Levin <sasha.levin@oracle.com> Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/tty_ldisc.c')
-rw-r--r--drivers/tty/tty_ldisc.c22
1 files changed, 20 insertions, 2 deletions
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 5bdc241628ac..1dbe27824220 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -326,6 +326,24 @@ static inline void __tty_ldisc_unlock(struct tty_struct *tty)
}
static int __lockfunc
+tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout)
+{
+ int ret;
+
+ ret = __tty_ldisc_lock(tty, timeout);
+ if (!ret)
+ return -EBUSY;
+ set_bit(TTY_LDISC_HALTED, &tty->flags);
+ return 0;
+}
+
+static void tty_ldisc_unlock(struct tty_struct *tty)
+{
+ clear_bit(TTY_LDISC_HALTED, &tty->flags);
+ __tty_ldisc_unlock(tty);
+}
+
+static int __lockfunc
tty_ldisc_lock_pair_timeout(struct tty_struct *tty, struct tty_struct *tty2,
unsigned long timeout)
{
@@ -682,7 +700,7 @@ void tty_ldisc_hangup(struct tty_struct *tty)
*
* Avoid racing set_ldisc or tty_ldisc_release
*/
- tty_ldisc_lock_pair(tty, tty->link);
+ tty_ldisc_lock(tty, MAX_SCHEDULE_TIMEOUT);
if (tty->ldisc) {
@@ -704,7 +722,7 @@ void tty_ldisc_hangup(struct tty_struct *tty)
WARN_ON(tty_ldisc_open(tty, tty->ldisc));
}
}
- tty_ldisc_enable_pair(tty, tty->link);
+ tty_ldisc_unlock(tty);
if (reset)
tty_reset_termios(tty);