Messages in this thread Patch in this message | | | From | Alan Cox <> | Subject | [PATCH 1/2] pty: Fix lock inversion | Date | Mon, 28 May 2012 10:49:10 +0100 |
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From: Alan Cox <alan@linux.intel.com>
The ptmx_open path takes the tty and devpts locks in the wrong order because tty_init_dev locks and returns a locked tty. As far as I can tell this is actually safe anyway because the tty being returned is new so nobody can get a reference to lock it at this point.
However we don't even need the devpts lock at this point, it's only held as a byproduct of the way the locks were pushed down.
Signed-off-by: Alan Cox <alan@linux.intel.com> ---
drivers/tty/pty.c | 2 -- 1 files changed, 0 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c index 59af394..65c7c62 100644 --- a/drivers/tty/pty.c +++ b/drivers/tty/pty.c @@ -633,7 +633,6 @@ static int ptmx_open(struct inode *inode, struct file *filp) mutex_unlock(&devpts_mutex); mutex_lock(&tty_mutex); - mutex_lock(&devpts_mutex); tty = tty_init_dev(ptm_driver, index); if (IS_ERR(tty)) { @@ -643,7 +642,6 @@ static int ptmx_open(struct inode *inode, struct file *filp) /* The tty returned here is locked so we can safely drop the mutex */ - mutex_unlock(&devpts_mutex); mutex_unlock(&tty_mutex); set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
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