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authorAlan Cox <alan@linux.intel.com>2012-05-04 01:24:08 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-05-05 03:58:47 +0400
commitd29f3ef39be4eec0362b985305fc526d9be318cf (patch)
tree35da6af15a899ca767841b864cb1ef290a0f3d4a /drivers/tty/pty.c
parentd739e65bb21d34f0f5d3bf4048410e534fbec148 (diff)
downloadlinux-d29f3ef39be4eec0362b985305fc526d9be318cf.tar.xz
tty_lock: Localise the lock
In each remaining case the tty_lock is associated with a specific tty. This means we can now lock on a per tty basis. We do need tty_lock_pair() for the pty case. Uglier but still a step in the right direction. [fixed up calls in 3 missing drivers - gregkh] Signed-off-by: Alan Cox <alan@linux.intel.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/pty.c')
-rw-r--r--drivers/tty/pty.c23
1 files changed, 13 insertions, 10 deletions
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index 5505ffc91da4..d6fa8429f3ff 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -47,6 +47,7 @@ static void pty_close(struct tty_struct *tty, struct file *filp)
wake_up_interruptible(&tty->read_wait);
wake_up_interruptible(&tty->write_wait);
tty->packet = 0;
+ /* Review - krefs on tty_link ?? */
if (!tty->link)
return;
tty->link->packet = 0;
@@ -62,9 +63,7 @@ static void pty_close(struct tty_struct *tty, struct file *filp)
mutex_unlock(&devpts_mutex);
}
#endif
- tty_unlock();
tty_vhangup(tty->link);
- tty_lock();
}
}
@@ -622,26 +621,29 @@ static int ptmx_open(struct inode *inode, struct file *filp)
return retval;
/* find a device that is not in use. */
- tty_lock();
+ mutex_lock(&devpts_mutex);
index = devpts_new_index(inode);
- tty_unlock();
if (index < 0) {
retval = index;
goto err_file;
}
+ mutex_unlock(&devpts_mutex);
+
mutex_lock(&tty_mutex);
mutex_lock(&devpts_mutex);
tty = tty_init_dev(ptm_driver, index);
- mutex_unlock(&devpts_mutex);
- tty_lock();
- mutex_unlock(&tty_mutex);
if (IS_ERR(tty)) {
retval = PTR_ERR(tty);
goto out;
}
+ /* 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 */
tty_add_file(tty, filp);
@@ -654,16 +656,17 @@ static int ptmx_open(struct inode *inode, struct file *filp)
if (retval)
goto err_release;
- tty_unlock();
+ tty_unlock(tty);
return 0;
err_release:
- tty_unlock();
+ tty_unlock(tty);
tty_release(inode, filp);
return retval;
out:
+ mutex_unlock(&tty_mutex);
devpts_kill_index(inode, index);
- tty_unlock();
err_file:
+ mutex_unlock(&devpts_mutex);
tty_free_file(filp);
return retval;
}