This is a note to let you know that I've just added the patch titled
Revert "tty: pty: Fix race condition between release_one_tty and
to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-testing branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will be merged to the tty-next branch sometime soon,
after it passes testing, and the merge window is open.
If you have any questions about this process, please let me know.
>From 0eae4686a128d87503863a261e84887750c8bc68 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Date: Fri, 29 Mar 2019 15:47:40 +0100
Subject: Revert "tty: pty: Fix race condition between release_one_tty and
pty_write"
This reverts commit b9ca5f8560af244489b4a1bc1ae88b341f24bc95 as 0-day
shows it has a circular locking dependency.
Fixes: b9ca5f8560af ("tty: pty: Fix race condition between release_one_tty and pty_write")
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Cc: Sahara <keun-o.park@xxxxxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/pty.c | 7 -------
drivers/tty/tty_io.c | 3 ---
2 files changed, 10 deletions(-)
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index ef72031ab5b9..00099a8439d2 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -116,12 +116,6 @@ static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
if (tty->stopped)
return 0;
- mutex_lock(&tty_mutex);
- if (to->magic != TTY_MAGIC) {
- mutex_unlock(&tty_mutex);
- return -EIO;
- }
-
if (c > 0) {
spin_lock_irqsave(&to->port->lock, flags);
/* Stuff the data into the input queue of the other end */
@@ -131,7 +125,6 @@ static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
tty_flip_buffer_push(to->port);
spin_unlock_irqrestore(&to->port->lock, flags);
}
- mutex_unlock(&tty_mutex);
return c;
}
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index c27777f3b8c4..5fa250157025 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1448,13 +1448,10 @@ static void release_one_tty(struct work_struct *work)
struct tty_driver *driver = tty->driver;
struct module *owner = driver->owner;
- mutex_lock(&tty_mutex);
if (tty->ops->cleanup)
tty->ops->cleanup(tty);
tty->magic = 0;
- mutex_unlock(&tty_mutex);
-
tty_driver_kref_put(driver);
module_put(owner);
--
2.21.0
