tty: Revert the tty locking series, it needs more work
Linus Torvalds [Sat, 2 Jun 2012 22:21:43 +0000 (15:21 -0700)]
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>

14 files changed:
drivers/tty/amiserial.c
drivers/tty/cyclades.c
drivers/tty/n_r3964.c
drivers/tty/pty.c
drivers/tty/serial/crisv10.c
drivers/tty/synclink.c
drivers/tty/synclink_gt.c
drivers/tty/synclinkmp.c
drivers/tty/tty_io.c
drivers/tty/tty_ldisc.c
drivers/tty/tty_mutex.c
drivers/tty/tty_port.c
include/linux/tty.h
net/bluetooth/rfcomm/tty.c

index 35819e3..6cc4358 100644 (file)
@@ -1033,7 +1033,7 @@ static int get_serial_info(struct tty_struct *tty, struct serial_state *state,
        if (!retinfo)
                return -EFAULT;
        memset(&tmp, 0, sizeof(tmp));
-       tty_lock(tty);
+       tty_lock();
        tmp.line = tty->index;
        tmp.port = state->port;
        tmp.flags = state->tport.flags;
@@ -1042,7 +1042,7 @@ static int get_serial_info(struct tty_struct *tty, struct serial_state *state,
        tmp.close_delay = state->tport.close_delay;
        tmp.closing_wait = state->tport.closing_wait;
        tmp.custom_divisor = state->custom_divisor;
-       tty_unlock(tty);
+       tty_unlock();
        if (copy_to_user(retinfo,&tmp,sizeof(*retinfo)))
                return -EFAULT;
        return 0;
@@ -1059,12 +1059,12 @@ static int set_serial_info(struct tty_struct *tty, struct serial_state *state,
        if (copy_from_user(&new_serial,new_info,sizeof(new_serial)))
                return -EFAULT;
 
-       tty_lock(tty);
+       tty_lock();
        change_spd = ((new_serial.flags ^ port->flags) & ASYNC_SPD_MASK) ||
                new_serial.custom_divisor != state->custom_divisor;
        if (new_serial.irq || new_serial.port != state->port ||
                        new_serial.xmit_fifo_size != state->xmit_fifo_size) {
-               tty_unlock(tty);
+               tty_unlock();
                return -EINVAL;
        }
   
@@ -1074,7 +1074,7 @@ static int set_serial_info(struct tty_struct *tty, struct serial_state *state,
                    (new_serial.xmit_fifo_size != state->xmit_fifo_size) ||
                    ((new_serial.flags & ~ASYNC_USR_MASK) !=
                     (port->flags & ~ASYNC_USR_MASK))) {
-                       tty_unlock(tty);
+                       tty_unlock();
                        return -EPERM;
                }
                port->flags = ((port->flags & ~ASYNC_USR_MASK) |
@@ -1084,7 +1084,7 @@ static int set_serial_info(struct tty_struct *tty, struct serial_state *state,
        }
 
        if (new_serial.baud_base < 9600) {
-               tty_unlock(tty);
+               tty_unlock();
                return -EINVAL;
        }
 
@@ -1116,7 +1116,7 @@ check_and_exit:
                }
        } else
                retval = startup(tty, state);
-       tty_unlock(tty);
+       tty_unlock();
        return retval;
 }
 
index 6984e1a..e61cabd 100644 (file)
@@ -1599,7 +1599,7 @@ static int cy_open(struct tty_struct *tty, struct file *filp)
         * If the port is the middle of closing, bail out now
         */
        if (tty_hung_up_p(filp) || (info->port.flags & ASYNC_CLOSING)) {
-               wait_event_interruptible_tty(tty, info->port.close_wait,
+               wait_event_interruptible_tty(info->port.close_wait,
                                !(info->port.flags & ASYNC_CLOSING));
                return (info->port.flags & ASYNC_HUP_NOTIFY) ? -EAGAIN: -ERESTARTSYS;
        }
index 656ad93..5c6c314 100644 (file)
@@ -1065,8 +1065,7 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
 
        TRACE_L("read()");
 
-       /* FIXME: should use a private lock */
-       tty_lock(tty);
+       tty_lock();
 
        pClient = findClient(pInfo, task_pid(current));
        if (pClient) {
@@ -1078,7 +1077,7 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
                                goto unlock;
                        }
                        /* block until there is a message: */
-                       wait_event_interruptible_tty(tty, pInfo->read_wait,
+                       wait_event_interruptible_tty(pInfo->read_wait,
                                        (pMsg = remove_msg(pInfo, pClient)));
                }
 
@@ -1108,7 +1107,7 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
        }
        ret = -EPERM;
 unlock:
-       tty_unlock(tty);
+       tty_unlock();
        return ret;
 }
 
@@ -1157,7 +1156,7 @@ static ssize_t r3964_write(struct tty_struct *tty, struct file *file,
        pHeader->locks = 0;
        pHeader->owner = NULL;
 
-       tty_lock(tty);
+       tty_lock();
 
        pClient = findClient(pInfo, task_pid(current));
        if (pClient) {
@@ -1176,7 +1175,7 @@ static ssize_t r3964_write(struct tty_struct *tty, struct file *file,
        add_tx_queue(pInfo, pHeader);
        trigger_transmit(pInfo);
 
-       tty_unlock(tty);
+       tty_unlock();
 
        return 0;
 }
index 65c7c62..5505ffc 100644 (file)
@@ -47,7 +47,6 @@ 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;
@@ -63,9 +62,9 @@ static void pty_close(struct tty_struct *tty, struct file *filp)
                        mutex_unlock(&devpts_mutex);
                }
 #endif
-               tty_unlock(tty);
+               tty_unlock();
                tty_vhangup(tty->link);
-               tty_lock(tty);
+               tty_lock();
        }
 }
 
@@ -623,27 +622,26 @@ static int ptmx_open(struct inode *inode, struct file *filp)
                return retval;
 
        /* find a device that is not in use. */
-       mutex_lock(&devpts_mutex);
+       tty_lock();
        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(&tty_mutex);
-
        set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 
        tty_add_file(tty, filp);
@@ -656,17 +654,16 @@ static int ptmx_open(struct inode *inode, struct file *filp)
        if (retval)
                goto err_release;
 
-       tty_unlock(tty);
+       tty_unlock();
        return 0;
 err_release:
-       tty_unlock(tty);
+       tty_unlock();
        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;
 }
index 7264d4d..80b6b1b 100644 (file)
@@ -3976,7 +3976,7 @@ block_til_ready(struct tty_struct *tty, struct file * filp,
         */
        if (tty_hung_up_p(filp) ||
            (info->flags & ASYNC_CLOSING)) {
-               wait_event_interruptible_tty(tty, info->close_wait,
+               wait_event_interruptible_tty(info->close_wait,
                        !(info->flags & ASYNC_CLOSING));
 #ifdef SERIAL_DO_RESTART
                if (info->flags & ASYNC_HUP_NOTIFY)
@@ -4052,9 +4052,9 @@ block_til_ready(struct tty_struct *tty, struct file * filp,
                printk("block_til_ready blocking: ttyS%d, count = %d\n",
                       info->line, info->count);
 #endif
-               tty_unlock(tty);
+               tty_unlock();
                schedule();
-               tty_lock(tty);
+               tty_lock();
        }
        set_current_state(TASK_RUNNING);
        remove_wait_queue(&info->open_wait, &wait);
@@ -4115,7 +4115,7 @@ rs_open(struct tty_struct *tty, struct file * filp)
         */
        if (tty_hung_up_p(filp) ||
            (info->flags & ASYNC_CLOSING)) {
-               wait_event_interruptible_tty(tty, info->close_wait,
+               wait_event_interruptible_tty(info->close_wait,
                        !(info->flags & ASYNC_CLOSING));
 #ifdef SERIAL_DO_RESTART
                return ((info->flags & ASYNC_HUP_NOTIFY) ?
index 5ed0daa..593d40a 100644 (file)
@@ -3338,9 +3338,9 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp,
                        printk("%s(%d):block_til_ready blocking on %s count=%d\n",
                                 __FILE__,__LINE__, tty->driver->name, port->count );
                                 
-               tty_unlock(tty);
+               tty_unlock();
                schedule();
-               tty_lock(tty);
+               tty_lock();
        }
        
        set_current_state(TASK_RUNNING);
index 45b43f1..aa1debf 100644 (file)
@@ -3336,9 +3336,9 @@ static int block_til_ready(struct tty_struct *tty, struct file *filp,
                }
 
                DBGINFO(("%s block_til_ready wait\n", tty->driver->name));
-               tty_unlock(tty);
+               tty_unlock();
                schedule();
-               tty_lock(tty);
+               tty_lock();
        }
 
        set_current_state(TASK_RUNNING);
index 4a1e4f0..a3dddc1 100644 (file)
@@ -3357,9 +3357,9 @@ static int block_til_ready(struct tty_struct *tty, struct file *filp,
                        printk("%s(%d):%s block_til_ready() count=%d\n",
                                 __FILE__,__LINE__, tty->driver->name, port->count );
 
-               tty_unlock(tty);
+               tty_unlock();
                schedule();
-               tty_lock(tty);
+               tty_lock();
        }
 
        set_current_state(TASK_RUNNING);
index 9e930c0..b425c79 100644 (file)
@@ -185,7 +185,6 @@ void free_tty_struct(struct tty_struct *tty)
                put_device(tty->dev);
        kfree(tty->write_buf);
        tty_buffer_free_all(tty);
-       tty->magic = 0xDEADDEAD;
        kfree(tty);
 }
 
@@ -574,7 +573,7 @@ void __tty_hangup(struct tty_struct *tty)
        }
        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 @@ void __tty_hangup(struct tty_struct *tty)
        clear_bit(TTY_HUPPING, &tty->flags);
        tty_ldisc_enable(tty);
 
-       tty_unlock(tty);
+       tty_unlock();
 
        if (f)
                fput(f);
@@ -1104,12 +1103,12 @@ void tty_write_message(struct tty_struct *tty, char *msg)
 {
        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 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
        }
        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 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
        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 @@ err_module_put:
 
        /* 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 @@ int tty_release(struct inode *inode, struct file *filp)
        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 @@ int tty_release(struct inode *inode, struct file *filp)
        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 @@ int tty_release(struct inode *inode, struct file *filp)
        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 @@ int tty_release(struct inode *inode, struct file *filp)
                   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 @@ int tty_release(struct inode *inode, struct file *filp)
 
                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 @@ int tty_release(struct inode *inode, struct file *filp)
 
        /* 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 @@ int tty_release(struct inode *inode, struct file *filp)
        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 @@ static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
  *     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 @@ retry_open:
        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 @@ retry_open:
        }
 
        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 @@ retry_open:
                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 @@ retry_open:
                /*
                 * 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(&current->sighand->siglock);
        if (!noctty &&
            current->signal->leader &&
@@ -2017,10 +2007,11 @@ retry_open:
            tty->session == NULL)
                __proc_set_tty(current, tty);
        spin_unlock_irq(&current->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 @@ out:
 
 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 @@ void initialize_tty_struct(struct tty_struct *tty,
        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);
index ba8be39..9911eb6 100644 (file)
@@ -568,7 +568,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
        if (IS_ERR(new_ldisc))
                return PTR_ERR(new_ldisc);
 
-       tty_lock(tty);
+       tty_lock();
        /*
         *      We need to look at the tty locking here for pty/tty pairs
         *      when both sides try to change in parallel.
@@ -582,12 +582,12 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
         */
 
        if (tty->ldisc->ops->num == ldisc) {
-               tty_unlock(tty);
+               tty_unlock();
                tty_ldisc_put(new_ldisc);
                return 0;
        }
 
-       tty_unlock(tty);
+       tty_unlock();
        /*
         *      Problem: What do we do if this blocks ?
         *      We could deadlock here
@@ -595,7 +595,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
        tty_wait_until_sent(tty, 0);
 
-       tty_lock(tty);
+       tty_lock();
        mutex_lock(&tty->ldisc_mutex);
 
        /*
@@ -605,10 +605,10 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
        while (test_bit(TTY_LDISC_CHANGING, &tty->flags)) {
                mutex_unlock(&tty->ldisc_mutex);
-               tty_unlock(tty);
+               tty_unlock();
                wait_event(tty_ldisc_wait,
                        test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0);
-               tty_lock(tty);
+               tty_lock();
                mutex_lock(&tty->ldisc_mutex);
        }
 
@@ -623,7 +623,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
        o_ldisc = tty->ldisc;
 
-       tty_unlock(tty);
+       tty_unlock();
        /*
         *      Make sure we don't change while someone holds a
         *      reference to the line discipline. The TTY_LDISC bit
@@ -650,7 +650,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
        retval = tty_ldisc_wait_idle(tty, 5 * HZ);
 
-       tty_lock(tty);
+       tty_lock();
        mutex_lock(&tty->ldisc_mutex);
 
        /* handle wait idle failure locked */
@@ -665,7 +665,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
                clear_bit(TTY_LDISC_CHANGING, &tty->flags);
                mutex_unlock(&tty->ldisc_mutex);
                tty_ldisc_put(new_ldisc);
-               tty_unlock(tty);
+               tty_unlock();
                return -EIO;
        }
 
@@ -708,7 +708,7 @@ enable:
        if (o_work)
                schedule_work(&o_tty->buf.work);
        mutex_unlock(&tty->ldisc_mutex);
-       tty_unlock(tty);
+       tty_unlock();
        return retval;
 }
 
@@ -816,11 +816,11 @@ void tty_ldisc_hangup(struct tty_struct *tty)
         * need to wait for another function taking the BTM
         */
        clear_bit(TTY_LDISC, &tty->flags);
-       tty_unlock(tty);
+       tty_unlock();
        cancel_work_sync(&tty->buf.work);
        mutex_unlock(&tty->ldisc_mutex);
 retry:
-       tty_lock(tty);
+       tty_lock();
        mutex_lock(&tty->ldisc_mutex);
 
        /* At this point we have a closed ldisc and we want to
@@ -831,7 +831,7 @@ retry:
                if (atomic_read(&tty->ldisc->users) != 1) {
                        char cur_n[TASK_COMM_LEN], tty_n[64];
                        long timeout = 3 * HZ;
-                       tty_unlock(tty);
+                       tty_unlock();
 
                        while (tty_ldisc_wait_idle(tty, timeout) == -EBUSY) {
                                timeout = MAX_SCHEDULE_TIMEOUT;
@@ -894,23 +894,6 @@ int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty)
        tty_ldisc_enable(tty);
        return 0;
 }
-
-static void tty_ldisc_kill(struct tty_struct *tty)
-{
-       mutex_lock(&tty->ldisc_mutex);
-       /*
-        * Now kill off the ldisc
-        */
-       tty_ldisc_close(tty, tty->ldisc);
-       tty_ldisc_put(tty->ldisc);
-       /* Force an oops if we mess this up */
-       tty->ldisc = NULL;
-
-       /* Ensure the next open requests the N_TTY ldisc */
-       tty_set_termios_ldisc(tty, N_TTY);
-       mutex_unlock(&tty->ldisc_mutex);
-}
-
 /**
  *     tty_ldisc_release               -       release line discipline
  *     @tty: tty being shut down
@@ -929,19 +912,27 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
         * race with the set_ldisc code path.
         */
 
-       tty_unlock_pair(tty, o_tty);
+       tty_unlock();
        tty_ldisc_halt(tty);
        tty_ldisc_flush_works(tty);
-       if (o_tty) {
-               tty_ldisc_halt(o_tty);
-               tty_ldisc_flush_works(o_tty);
-       }
-       tty_lock_pair(tty, o_tty);
+       tty_lock();
 
+       mutex_lock(&tty->ldisc_mutex);
+       /*
+        * Now kill off the ldisc
+        */
+       tty_ldisc_close(tty, tty->ldisc);
+       tty_ldisc_put(tty->ldisc);
+       /* Force an oops if we mess this up */
+       tty->ldisc = NULL;
+
+       /* Ensure the next open requests the N_TTY ldisc */
+       tty_set_termios_ldisc(tty, N_TTY);
+       mutex_unlock(&tty->ldisc_mutex);
 
-       tty_ldisc_kill(tty);
+       /* This will need doing differently if we need to lock */
        if (o_tty)
-               tty_ldisc_kill(o_tty);
+               tty_ldisc_release(o_tty, NULL);
 
        /* And the memory resources remaining (buffers, termios) will be
           disposed of when the kref hits zero */
index 67feac9..9ff986c 100644 (file)
@@ -4,70 +4,29 @@
 #include <linux/semaphore.h>
 #include <linux/sched.h>
 
-/* Legacy tty mutex glue */
-
-enum {
-       TTY_MUTEX_NORMAL,
-       TTY_MUTEX_NESTED,
-};
+/*
+ * The 'big tty mutex'
+ *
+ * This mutex is taken and released by tty_lock() and tty_unlock(),
+ * replacing the older big kernel lock.
+ * It can no longer be taken recursively, and does not get
+ * released implicitly while sleeping.
+ *
+ * Don't use in new code.
+ */
+static DEFINE_MUTEX(big_tty_mutex);
 
 /*
  * Getting the big tty mutex.
  */
-
-static void __lockfunc tty_lock_nested(struct tty_struct *tty,
-                                      unsigned int subclass)
+void __lockfunc tty_lock(void)
 {
-       if (tty->magic != TTY_MAGIC) {
-               printk(KERN_ERR "L Bad %p\n", tty);
-               WARN_ON(1);
-               return;
-       }
-       tty_kref_get(tty);
-       mutex_lock_nested(&tty->legacy_mutex, subclass);
-}
-
-void __lockfunc tty_lock(struct tty_struct *tty)
-{
-       return tty_lock_nested(tty, TTY_MUTEX_NORMAL);
+       mutex_lock(&big_tty_mutex);
 }
 EXPORT_SYMBOL(tty_lock);
 
-void __lockfunc tty_unlock(struct tty_struct *tty)
+void __lockfunc tty_unlock(void)
 {
-       if (tty->magic != TTY_MAGIC) {
-               printk(KERN_ERR "U Bad %p\n", tty);
-               WARN_ON(1);
-               return;
-       }
-       mutex_unlock(&tty->legacy_mutex);
-       tty_kref_put(tty);
+       mutex_unlock(&big_tty_mutex);
 }
 EXPORT_SYMBOL(tty_unlock);
-
-/*
- * Getting the big tty mutex for a pair of ttys with lock ordering
- * On a non pty/tty pair tty2 can be NULL which is just fine.
- */
-void __lockfunc tty_lock_pair(struct tty_struct *tty,
-                                       struct tty_struct *tty2)
-{
-       if (tty < tty2) {
-               tty_lock(tty);
-               tty_lock_nested(tty2, TTY_MUTEX_NESTED);
-       } else {
-               if (tty2 && tty2 != tty)
-                       tty_lock(tty2);
-               tty_lock_nested(tty, TTY_MUTEX_NESTED);
-       }
-}
-EXPORT_SYMBOL(tty_lock_pair);
-
-void __lockfunc tty_unlock_pair(struct tty_struct *tty,
-                                               struct tty_struct *tty2)
-{
-       tty_unlock(tty);
-       if (tty2 && tty2 != tty)
-               tty_unlock(tty2);
-}
-EXPORT_SYMBOL(tty_unlock_pair);
index d9cca95..bf6e238 100644 (file)
@@ -230,7 +230,7 @@ int tty_port_block_til_ready(struct tty_port *port,
 
        /* block if port is in the process of being closed */
        if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) {
-               wait_event_interruptible_tty(tty, port->close_wait,
+               wait_event_interruptible_tty(port->close_wait,
                                !(port->flags & ASYNC_CLOSING));
                if (port->flags & ASYNC_HUP_NOTIFY)
                        return -EAGAIN;
@@ -296,9 +296,9 @@ int tty_port_block_til_ready(struct tty_port *port,
                        retval = -ERESTARTSYS;
                        break;
                }
-               tty_unlock(tty);
+               tty_unlock();
                schedule();
-               tty_lock(tty);
+               tty_lock();
        }
        finish_wait(&port->open_wait, &wait);
 
index 4990ef2..9f47ab5 100644 (file)
@@ -268,7 +268,6 @@ struct tty_struct {
        struct mutex ldisc_mutex;
        struct tty_ldisc *ldisc;
 
-       struct mutex legacy_mutex;
        struct mutex termios_mutex;
        spinlock_t ctrl_lock;
        /* Termios values are protected by the termios mutex */
@@ -606,12 +605,8 @@ extern long vt_compat_ioctl(struct tty_struct *tty,
 
 /* tty_mutex.c */
 /* functions for preparation of BKL removal */
-extern void __lockfunc tty_lock(struct tty_struct *tty);
-extern void __lockfunc tty_unlock(struct tty_struct *tty);
-extern void __lockfunc tty_lock_pair(struct tty_struct *tty,
-                               struct tty_struct *tty2);
-extern void __lockfunc tty_unlock_pair(struct tty_struct *tty,
-                               struct tty_struct *tty2);
+extern void __lockfunc tty_lock(void) __acquires(tty_lock);
+extern void __lockfunc tty_unlock(void) __releases(tty_lock);
 
 /*
  * this shall be called only from where BTM is held (like close)
@@ -626,9 +621,9 @@ extern void __lockfunc tty_unlock_pair(struct tty_struct *tty,
 static inline void tty_wait_until_sent_from_close(struct tty_struct *tty,
                long timeout)
 {
-       tty_unlock(tty); /* tty->ops->close holds the BTM, drop it while waiting */
+       tty_unlock(); /* tty->ops->close holds the BTM, drop it while waiting */
        tty_wait_until_sent(tty, timeout);
-       tty_lock(tty);
+       tty_lock();
 }
 
 /*
@@ -643,16 +638,16 @@ static inline void tty_wait_until_sent_from_close(struct tty_struct *tty,
  *
  * Do not use in new code.
  */
-#define wait_event_interruptible_tty(tty, wq, condition)               \
+#define wait_event_interruptible_tty(wq, condition)                    \
 ({                                                                     \
        int __ret = 0;                                                  \
        if (!(condition)) {                                             \
-               __wait_event_interruptible_tty(tty, wq, condition, __ret);      \
+               __wait_event_interruptible_tty(wq, condition, __ret);   \
        }                                                               \
        __ret;                                                          \
 })
 
-#define __wait_event_interruptible_tty(tty, wq, condition, ret)                \
+#define __wait_event_interruptible_tty(wq, condition, ret)             \
 do {                                                                   \
        DEFINE_WAIT(__wait);                                            \
                                                                        \
@@ -661,9 +656,9 @@ do {                                                                        \
                if (condition)                                          \
                        break;                                          \
                if (!signal_pending(current)) {                         \
-                       tty_unlock(tty);                                        \
+                       tty_unlock();                                   \
                        schedule();                                     \
-                       tty_lock(tty);                                  \
+                       tty_lock();                                     \
                        continue;                                       \
                }                                                       \
                ret = -ERESTARTSYS;                                     \
index aa5d73b..d1820ff 100644 (file)
@@ -710,9 +710,9 @@ static int rfcomm_tty_open(struct tty_struct *tty, struct file *filp)
                        break;
                }
 
-               tty_unlock(tty);
+               tty_unlock();
                schedule();
-               tty_lock(tty);
+               tty_lock();
        }
        set_current_state(TASK_RUNNING);
        remove_wait_queue(&dev->wait, &wait);