From 0eae4686a128d87503863a261e84887750c8bc68 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman 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 Cc: Sahara Cc: stable Signed-off-by: Greg Kroah-Hartman --- 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); -- cgit v1.2.3-59-g8ed1b