The commit is pushed to "branch-rh7-3.10.0-327.3.1-vz7.10.x-ovz" and will
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.3.1.vz7.10.8
------>
commit ab9f5d42ce7c9c35e7e2e9066f7873a0a9f889a1
Author: Cyrill Gorcunov <[email protected]>
Date: Fri Jan 29 18:49:15 2016 +0400
ms/tty: Invert tty_lock/ldisc_sem lock order
ML: c8483bc9deff9bf9118aaab2e840b973b75cac3e
From: Peter Hurley <[email protected]>
Date: Wed, 5 Nov 2014 12:12:45 -0500
Dropping the tty lock to acquire the tty->ldisc_sem allows several
race conditions (such as hangup while changing the ldisc) which requires
extra states and testing. The ldisc_sem->tty_lock lock order has
not been required since tty buffer ownership was moved to tty_port.
Reviewed-by: Alan Cox <[email protected]>
Signed-off-by: Peter Hurley <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
https://jira.sw.ru/browse/PSBM-43454
Signed-off-by: Cyrill Gorcunov <[email protected]>
CC: Vladimir Davydov <[email protected]>
CC: Konstantin Khorenko <[email protected]>
---
drivers/tty/tty_ldisc.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index d389c82..d1b8ef5 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -524,9 +524,11 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
if (IS_ERR(new_ldisc))
return PTR_ERR(new_ldisc);
+ tty_lock(tty);
retval = tty_ldisc_lock_pair_timeout(tty, o_tty, 5 * HZ);
if (retval) {
tty_ldisc_put(new_ldisc);
+ tty_unlock(tty);
return retval;
}
@@ -537,6 +539,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
if (tty->ldisc->ops->num == ldisc) {
tty_ldisc_enable_pair(tty, o_tty);
tty_ldisc_put(new_ldisc);
+ tty_unlock(tty);
return 0;
}
@@ -544,7 +547,6 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
tty->receive_room = 0;
o_ldisc = tty->ldisc;
- tty_lock(tty);
/* FIXME: for testing only */
WARN_ON(test_bit(TTY_HUPPED, &tty->flags));
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