tty: Revert the tty locking series, it needs more work
This reverts the tty layer change to use per-tty locking, because it's
not correct yet, and fixing it will require some more deep surgery.
The main revert is d29f3ef39be4 ("tty_lock: Localise the lock"), but
there are several smaller commits that built upon it, they also get
reverted here. The list of reverted commits is:
fde86d310886 - tty: add lockdep annotations
8f6576ad476b - tty: fix ldisc lock inversion trace
d3ca8b64b97e - pty: Fix lock inversion
b1d679afd766 - tty: drop the pty lock during hangup
abcefe5fc357 - tty/amiserial: Add missing argument for tty_unlock()
fd11b42e3598 - cris: fix missing tty arg in wait_event_interruptible_tty call
d29f3ef39be4 - tty_lock: Localise the lock
The revert had a trivial conflict in the 68360serial.c staging driver
that got removed in the meantime.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 9e930c0..b425c79 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -185,7 +185,6 @@
put_device(tty->dev);
kfree(tty->write_buf);
tty_buffer_free_all(tty);
- tty->magic = 0xDEADDEAD;
kfree(tty);
}
@@ -574,7 +573,7 @@
}
spin_unlock(&redirect_lock);
- tty_lock(tty);
+ tty_lock();
/* some functions below drop BTM, so we need this bit */
set_bit(TTY_HUPPING, &tty->flags);
@@ -667,7 +666,7 @@
clear_bit(TTY_HUPPING, &tty->flags);
tty_ldisc_enable(tty);
- tty_unlock(tty);
+ tty_unlock();
if (f)
fput(f);
@@ -1104,12 +1103,12 @@
{
if (tty) {
mutex_lock(&tty->atomic_write_lock);
- tty_lock(tty);
+ tty_lock();
if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags)) {
- tty_unlock(tty);
+ tty_unlock();
tty->ops->write(tty, msg, strlen(msg));
} else
- tty_unlock(tty);
+ tty_unlock();
tty_write_unlock(tty);
}
return;
@@ -1404,7 +1403,6 @@
}
initialize_tty_struct(tty, driver, idx);
- tty_lock(tty);
retval = tty_driver_install_tty(driver, tty);
if (retval < 0)
goto err_deinit_tty;
@@ -1417,11 +1415,9 @@
retval = tty_ldisc_setup(tty, tty->link);
if (retval)
goto err_release_tty;
- /* Return the tty locked so that it cannot vanish under the caller */
return tty;
err_deinit_tty:
- tty_unlock(tty);
deinitialize_tty_struct(tty);
free_tty_struct(tty);
err_module_put:
@@ -1430,7 +1426,6 @@
/* call the tty release_tty routine to clean out this slot */
err_release_tty:
- tty_unlock(tty);
printk_ratelimited(KERN_INFO "tty_init_dev: ldisc open failed, "
"clearing slot %d\n", idx);
release_tty(tty, idx);
@@ -1633,7 +1628,7 @@
if (tty_paranoia_check(tty, inode, __func__))
return 0;
- tty_lock(tty);
+ tty_lock();
check_tty_count(tty, __func__);
__tty_fasync(-1, filp, 0);
@@ -1642,11 +1637,10 @@
pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER);
devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
- /* Review: parallel close */
o_tty = tty->link;
if (tty_release_checks(tty, o_tty, idx)) {
- tty_unlock(tty);
+ tty_unlock();
return 0;
}
@@ -1658,7 +1652,7 @@
if (tty->ops->close)
tty->ops->close(tty, filp);
- tty_unlock(tty);
+ tty_unlock();
/*
* Sanity check: if tty->count is going to zero, there shouldn't be
* any waiters on tty->read_wait or tty->write_wait. We test the
@@ -1681,7 +1675,7 @@
opens on /dev/tty */
mutex_lock(&tty_mutex);
- tty_lock_pair(tty, o_tty);
+ tty_lock();
tty_closing = tty->count <= 1;
o_tty_closing = o_tty &&
(o_tty->count <= (pty_master ? 1 : 0));
@@ -1712,7 +1706,7 @@
printk(KERN_WARNING "%s: %s: read/write wait queue active!\n",
__func__, tty_name(tty, buf));
- tty_unlock_pair(tty, o_tty);
+ tty_unlock();
mutex_unlock(&tty_mutex);
schedule();
}
@@ -1775,7 +1769,7 @@
/* check whether both sides are closing ... */
if (!tty_closing || (o_tty && !o_tty_closing)) {
- tty_unlock_pair(tty, o_tty);
+ tty_unlock();
return 0;
}
@@ -1788,16 +1782,14 @@
tty_ldisc_release(tty, o_tty);
/*
* The release_tty function takes care of the details of clearing
- * the slots and preserving the termios structure. The tty_unlock_pair
- * should be safe as we keep a kref while the tty is locked (so the
- * unlock never unlocks a freed tty).
+ * the slots and preserving the termios structure.
*/
release_tty(tty, idx);
- tty_unlock_pair(tty, o_tty);
/* Make this pty number available for reallocation */
if (devpts)
devpts_kill_index(inode, idx);
+ tty_unlock();
return 0;
}
@@ -1901,9 +1893,6 @@
* Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
* tty->count should protect the rest.
* ->siglock protects ->signal/->sighand
- *
- * Note: the tty_unlock/lock cases without a ref are only safe due to
- * tty_mutex
*/
static int tty_open(struct inode *inode, struct file *filp)
@@ -1927,7 +1916,8 @@
retval = 0;
mutex_lock(&tty_mutex);
- /* This is protected by the tty_mutex */
+ tty_lock();
+
tty = tty_open_current_tty(device, filp);
if (IS_ERR(tty)) {
retval = PTR_ERR(tty);
@@ -1948,19 +1938,17 @@
}
if (tty) {
- tty_lock(tty);
retval = tty_reopen(tty);
- if (retval < 0) {
- tty_unlock(tty);
+ if (retval)
tty = ERR_PTR(retval);
- }
- } else /* Returns with the tty_lock held for now */
+ } else
tty = tty_init_dev(driver, index);
mutex_unlock(&tty_mutex);
if (driver)
tty_driver_kref_put(driver);
if (IS_ERR(tty)) {
+ tty_unlock();
retval = PTR_ERR(tty);
goto err_file;
}
@@ -1989,7 +1977,7 @@
printk(KERN_DEBUG "%s: error %d in opening %s...\n", __func__,
retval, tty->name);
#endif
- tty_unlock(tty); /* need to call tty_release without BTM */
+ tty_unlock(); /* need to call tty_release without BTM */
tty_release(inode, filp);
if (retval != -ERESTARTSYS)
return retval;
@@ -2001,15 +1989,17 @@
/*
* Need to reset f_op in case a hangup happened.
*/
+ tty_lock();
if (filp->f_op == &hung_up_tty_fops)
filp->f_op = &tty_fops;
+ tty_unlock();
goto retry_open;
}
- tty_unlock(tty);
+ tty_unlock();
mutex_lock(&tty_mutex);
- tty_lock(tty);
+ tty_lock();
spin_lock_irq(¤t->sighand->siglock);
if (!noctty &&
current->signal->leader &&
@@ -2017,10 +2007,11 @@
tty->session == NULL)
__proc_set_tty(current, tty);
spin_unlock_irq(¤t->sighand->siglock);
- tty_unlock(tty);
+ tty_unlock();
mutex_unlock(&tty_mutex);
return 0;
err_unlock:
+ tty_unlock();
mutex_unlock(&tty_mutex);
/* after locks to avoid deadlock */
if (!IS_ERR_OR_NULL(driver))
@@ -2103,13 +2094,10 @@
static int tty_fasync(int fd, struct file *filp, int on)
{
- struct tty_struct *tty = file_tty(filp);
int retval;
-
- tty_lock(tty);
+ tty_lock();
retval = __tty_fasync(fd, filp, on);
- tty_unlock(tty);
-
+ tty_unlock();
return retval;
}
@@ -2946,7 +2934,6 @@
tty->pgrp = NULL;
tty->overrun_time = jiffies;
tty_buffer_init(tty);
- mutex_init(&tty->legacy_mutex);
mutex_init(&tty->termios_mutex);
mutex_init(&tty->ldisc_mutex);
init_waitqueue_head(&tty->write_wait);