tty: localise the lock

The termios and other changes mean the other protections needed on the driver
tty arrays should be adequate. Turn it all back on.

This contains pieces folded in from the fixes made to the original patches

| From: Geert Uytterhoeven <geert@linux-m68k.org>	(fix m68k)
| From: Paul Gortmaker <paul.gortmaker@windriver.com>	(fix cris)
| From: Jiri Kosina <jkosina@suze.cz>			(lockdep)
| From: Eric Dumazet <eric.dumazet@gmail.com>		(lockdep)

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/amiserial.c b/drivers/tty/amiserial.c
index 6cc4358f68c12ad2c779c7837207ce875968cf40..35819e31262472140be9ec2dfa5210a087a43be1 100644 (file)
--- a/drivers/tty/amiserial.c
+++ b/drivers/tty/amiserial.c
@@ -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_lock(tty);
        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_unlock(tty);
        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_lock(tty);
        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_unlock(tty);
                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_unlock(tty);
                        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_unlock(tty);
                return -EINVAL;
        }
 
@@ -1116,7 +1116,7 @@ check_and_exit:
                }
        } else
                retval = startup(tty, state);
-       tty_unlock();
+       tty_unlock(tty);
        return retval;
 }
 

diff --git a/drivers/tty/cyclades.c b/drivers/tty/cyclades.c
index cff546839db92b41ae92bf7c2535c01ad2b7205e..69e9ca2dd4b3ec5ccdf3d722fbe90c16249a0faf 100644 (file)
--- a/drivers/tty/cyclades.c
+++ b/drivers/tty/cyclades.c
@@ -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(info->port.close_wait,
+               wait_event_interruptible_tty(tty, info->port.close_wait,
                                !(info->port.flags & ASYNC_CLOSING));
                return (info->port.flags & ASYNC_HUP_NOTIFY) ? -EAGAIN: -ERESTARTSYS;
        }

diff --git a/drivers/tty/n_r3964.c b/drivers/tty/n_r3964.c
index 5c6c31459a2f6618cb7cf9d83c7100cf1a6d86ea..1e6405070ce649e356b24d272a824e9eda737159 100644 (file)
--- a/drivers/tty/n_r3964.c
+++ b/drivers/tty/n_r3964.c
@@ -1065,7 +1065,7 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
 
        TRACE_L("read()");
 
-       tty_lock();
+       tty_lock(tty);
 
        pClient = findClient(pInfo, task_pid(current));
        if (pClient) {
@@ -1077,7 +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(pInfo->read_wait,
+                       wait_event_interruptible_tty(tty, pInfo->read_wait,
                                        (pMsg = remove_msg(pInfo, pClient)));
                }
 
@@ -1107,7 +1107,7 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
        }
        ret = -EPERM;
 unlock:
-       tty_unlock();
+       tty_unlock(tty);
        return ret;
 }
 
@@ -1156,7 +1156,7 @@ static ssize_t r3964_write(struct tty_struct *tty, struct file *file,
        pHeader->locks = 0;
        pHeader->owner = NULL;
 
-       tty_lock();
+       tty_lock(tty);
 
        pClient = findClient(pInfo, task_pid(current));
        if (pClient) {
@@ -1175,7 +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_unlock(tty);
 
        return 0;
 }

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index b50fc1c014159386cfbf3a2ce05cebf6b1eb075e..d8558834ce572d8e46f830f8042917d417aefe08 100644 (file)
--- 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 +63,9 @@ static void pty_close(struct tty_struct *tty, struct file *filp)
                        mutex_unlock(&devpts_mutex);
                }
 #endif
-               tty_unlock();
+               tty_unlock(tty);
                tty_vhangup(tty->link);
-               tty_lock();
+               tty_lock(tty);
        }
 }
 
@@ -615,26 +616,27 @@ 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(&tty_mutex);
+
        set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 
        tty_add_file(tty, filp);
@@ -647,16 +649,17 @@ 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;
 }

diff --git a/drivers/tty/serial/crisv10.c b/drivers/tty/serial/crisv10.c
index 80b6b1b1f7257d3b1da80f1b58523e7465bdb36b..7264d4d2671774651267d7d98e5c4a44aff7f946 100644 (file)
--- a/drivers/tty/serial/crisv10.c
+++ b/drivers/tty/serial/crisv10.c
@@ -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(info->close_wait,
+               wait_event_interruptible_tty(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_unlock(tty);
                schedule();
-               tty_lock();
+               tty_lock(tty);
        }
        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(info->close_wait,
+               wait_event_interruptible_tty(tty, info->close_wait,
                        !(info->flags & ASYNC_CLOSING));
 #ifdef SERIAL_DO_RESTART
                return ((info->flags & ASYNC_HUP_NOTIFY) ?

diff --git a/drivers/tty/synclink.c b/drivers/tty/synclink.c
index 593d40ad0a6be9b0de161803aa69c9011e2fdab8..5ed0daae65647c366dc9948307440795b8eda39b 100644 (file)
--- a/drivers/tty/synclink.c
+++ b/drivers/tty/synclink.c
@@ -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_unlock(tty);
                schedule();
-               tty_lock();
+               tty_lock(tty);
        }
        
        set_current_state(TASK_RUNNING);

diff --git a/drivers/tty/synclink_gt.c b/drivers/tty/synclink_gt.c
index aa1debf97cc741e3f5914cb5396c8397bd37f362..45b43f11ca3927df3c1c680076c883808f600db9 100644 (file)
--- a/drivers/tty/synclink_gt.c
+++ b/drivers/tty/synclink_gt.c
@@ -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_unlock(tty);
                schedule();
-               tty_lock();
+               tty_lock(tty);
        }
 
        set_current_state(TASK_RUNNING);

diff --git a/drivers/tty/synclinkmp.c b/drivers/tty/synclinkmp.c
index a3dddc12d2fedc3ec261c2c8f2b3da215f564a20..4a1e4f07765bbce2872b394560d3cc0c93a1ece4 100644 (file)
--- a/drivers/tty/synclinkmp.c
+++ b/drivers/tty/synclinkmp.c
@@ -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_unlock(tty);
                schedule();
-               tty_lock();
+               tty_lock(tty);
        }
 
        set_current_state(TASK_RUNNING);

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index ac96f74573d0e8c9bd5225285002abe364f8a84f..ca7c25d9f6d5347322cf80f7ac54d5c47df9c7ab 100644 (file)
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -185,6 +185,7 @@ 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);
 }
 
@@ -573,7 +574,7 @@ void __tty_hangup(struct tty_struct *tty)
        }
        spin_unlock(&redirect_lock);
 
-       tty_lock();
+       tty_lock(tty);
 
        /* some functions below drop BTM, so we need this bit */
        set_bit(TTY_HUPPING, &tty->flags);
@@ -666,7 +667,7 @@ void __tty_hangup(struct tty_struct *tty)
        clear_bit(TTY_HUPPING, &tty->flags);
        tty_ldisc_enable(tty);
 
-       tty_unlock();
+       tty_unlock(tty);
 
        if (f)
                fput(f);
@@ -1103,12 +1104,12 @@ void tty_write_message(struct tty_struct *tty, char *msg)
 {
        if (tty) {
                mutex_lock(&tty->atomic_write_lock);
-               tty_lock();
+               tty_lock(tty);
                if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags)) {
-                       tty_unlock();
+                       tty_unlock(tty);
                        tty->ops->write(tty, msg, strlen(msg));
                } else
-                       tty_unlock();
+                       tty_unlock(tty);
                tty_write_unlock(tty);
        }
        return;
@@ -1403,6 +1404,7 @@ 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;
@@ -1418,9 +1420,11 @@ 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:
@@ -1429,6 +1433,7 @@ 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);
@@ -1631,7 +1636,7 @@ int tty_release(struct inode *inode, struct file *filp)
        if (tty_paranoia_check(tty, inode, __func__))
                return 0;
 
-       tty_lock();
+       tty_lock(tty);
        check_tty_count(tty, __func__);
 
        __tty_fasync(-1, filp, 0);
@@ -1640,10 +1645,11 @@ 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_unlock(tty);
                return 0;
        }
 
@@ -1655,7 +1661,7 @@ int tty_release(struct inode *inode, struct file *filp)
        if (tty->ops->close)
                tty->ops->close(tty, filp);
 
-       tty_unlock();
+       tty_unlock(tty);
        /*
         * 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
@@ -1678,7 +1684,7 @@ int tty_release(struct inode *inode, struct file *filp)
                   opens on /dev/tty */
 
                mutex_lock(&tty_mutex);
-               tty_lock();
+               tty_lock_pair(tty, o_tty);
                tty_closing = tty->count <= 1;
                o_tty_closing = o_tty &&
                        (o_tty->count <= (pty_master ? 1 : 0));
@@ -1709,7 +1715,7 @@ 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();
+               tty_unlock_pair(tty, o_tty);
                mutex_unlock(&tty_mutex);
                schedule();
        }
@@ -1772,7 +1778,7 @@ 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();
+               tty_unlock_pair(tty, o_tty);
                return 0;
        }
 
@@ -1785,14 +1791,16 @@ 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 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).
         */
        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;
 }
 
@@ -1896,6 +1904,9 @@ 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)
@@ -1919,8 +1930,7 @@ retry_open:
        retval = 0;
 
        mutex_lock(&tty_mutex);
-       tty_lock();
-
+       /* This is protected by the tty_mutex */
        tty = tty_open_current_tty(device, filp);
        if (IS_ERR(tty)) {
                retval = PTR_ERR(tty);
@@ -1941,17 +1951,19 @@ retry_open:
        }
 
        if (tty) {
+               tty_lock(tty);
                retval = tty_reopen(tty);
-               if (retval)
+               if (retval < 0) {
+                       tty_unlock(tty);
                        tty = ERR_PTR(retval);
-       } else
+               }
+       } else  /* Returns with the tty_lock held for now */
                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;
        }
@@ -1980,7 +1992,7 @@ retry_open:
                printk(KERN_DEBUG "%s: error %d in opening %s...\n", __func__,
                                retval, tty->name);
 #endif
-               tty_unlock(); /* need to call tty_release without BTM */
+               tty_unlock(tty); /* need to call tty_release without BTM */
                tty_release(inode, filp);
                if (retval != -ERESTARTSYS)
                        return retval;
@@ -1992,17 +2004,15 @@ 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_unlock(tty);
 
 
        mutex_lock(&tty_mutex);
-       tty_lock();
+       tty_lock(tty);
        spin_lock_irq(&current->sighand->siglock);
        if (!noctty &&
            current->signal->leader &&
@@ -2010,11 +2020,10 @@ retry_open:
            tty->session == NULL)
                __proc_set_tty(current, tty);
        spin_unlock_irq(&current->sighand->siglock);
-       tty_unlock();
+       tty_unlock(tty);
        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))
@@ -2097,10 +2106,13 @@ out:
 
 static int tty_fasync(int fd, struct file *filp, int on)
 {
+       struct tty_struct *tty = file_tty(filp);
        int retval;
-       tty_lock();
+
+       tty_lock(tty);
        retval = __tty_fasync(fd, filp, on);
-       tty_unlock();
+       tty_unlock(tty);
+
        return retval;
 }
 
@@ -2937,6 +2949,7 @@ 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);

diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 9911eb6b34cd06c772cadf9761647b1dc5828487..ba8be396a6215339200c5ff3f79ad34e93489acb 100644 (file)
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -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_lock(tty);
        /*
         *      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_unlock(tty);
                tty_ldisc_put(new_ldisc);
                return 0;
        }
 
-       tty_unlock();
+       tty_unlock(tty);
        /*
         *      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_lock(tty);
        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_unlock(tty);
                wait_event(tty_ldisc_wait,
                        test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0);
-               tty_lock();
+               tty_lock(tty);
                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_unlock(tty);
        /*
         *      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_lock(tty);
        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_unlock(tty);
                return -EIO;
        }
 
@@ -708,7 +708,7 @@ enable:
        if (o_work)
                schedule_work(&o_tty->buf.work);
        mutex_unlock(&tty->ldisc_mutex);
-       tty_unlock();
+       tty_unlock(tty);
        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_unlock(tty);
        cancel_work_sync(&tty->buf.work);
        mutex_unlock(&tty->ldisc_mutex);
 retry:
-       tty_lock();
+       tty_lock(tty);
        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_unlock(tty);
 
                        while (tty_ldisc_wait_idle(tty, timeout) == -EBUSY) {
                                timeout = MAX_SCHEDULE_TIMEOUT;
@@ -894,6 +894,23 @@ 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
@@ -912,27 +929,19 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
         * race with the set_ldisc code path.
         */
 
-       tty_unlock();
+       tty_unlock_pair(tty, o_tty);
        tty_ldisc_halt(tty);
        tty_ldisc_flush_works(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;
+       if (o_tty) {
+               tty_ldisc_halt(o_tty);
+               tty_ldisc_flush_works(o_tty);
+       }
+       tty_lock_pair(tty, o_tty);
 
-       /* Ensure the next open requests the N_TTY ldisc */
-       tty_set_termios_ldisc(tty, N_TTY);
-       mutex_unlock(&tty->ldisc_mutex);
 
-       /* This will need doing differently if we need to lock */
+       tty_ldisc_kill(tty);
        if (o_tty)
-               tty_ldisc_release(o_tty, NULL);
+               tty_ldisc_kill(o_tty);
 
        /* And the memory resources remaining (buffers, termios) will be
           disposed of when the kref hits zero */

diff --git a/drivers/tty/tty_mutex.c b/drivers/tty/tty_mutex.c
index 9ff986c32a21ef702edf515a79c19440a504b747..67feac9e6ebbef7e224c47672bff95f7f511c5a2 100644 (file)
--- a/drivers/tty/tty_mutex.c
+++ b/drivers/tty/tty_mutex.c
@@ -4,29 +4,70 @@
 #include <linux/semaphore.h>
 #include <linux/sched.h>
 
-/*
- * 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);
+/* Legacy tty mutex glue */
+
+enum {
+       TTY_MUTEX_NORMAL,
+       TTY_MUTEX_NESTED,
+};
 
 /*
  * Getting the big tty mutex.
  */
-void __lockfunc tty_lock(void)
+
+static void __lockfunc tty_lock_nested(struct tty_struct *tty,
+                                      unsigned int subclass)
 {
-       mutex_lock(&big_tty_mutex);
+       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);
 }
 EXPORT_SYMBOL(tty_lock);
 
-void __lockfunc tty_unlock(void)
+void __lockfunc tty_unlock(struct tty_struct *tty)
 {
-       mutex_unlock(&big_tty_mutex);
+       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);
 }
 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);

diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index 4e9d2b291f4a3095dd269d5f5621ccfeb5ce7942..a3ba776c574c88aa78be293f6a8ba26bbe89a933 100644 (file)
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -239,7 +239,7 @@ 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(port->close_wait,
+               wait_event_interruptible_tty(tty, port->close_wait,
                                !(port->flags & ASYNC_CLOSING));
                if (port->flags & ASYNC_HUP_NOTIFY)
                        return -EAGAIN;
@@ -305,9 +305,9 @@ int tty_port_block_til_ready(struct tty_port *port,
                        retval = -ERESTARTSYS;
                        break;
                }
-               tty_unlock();
+               tty_unlock(tty);
                schedule();
-               tty_lock();
+               tty_lock(tty);
        }
        finish_wait(&port->open_wait, &wait);
 

diff --git a/include/linux/tty.h b/include/linux/tty.h
index 40b18d7ad929c134796662dc2c974964babb8448..7f9d7df9b1316f0b18cb392e11acde6fcc6ede95 100644 (file)
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -268,6 +268,7 @@ 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 */
@@ -610,8 +611,12 @@ extern long vt_compat_ioctl(struct tty_struct *tty,
 
 /* tty_mutex.c */
 /* functions for preparation of BKL removal */
-extern void __lockfunc tty_lock(void) __acquires(tty_lock);
-extern void __lockfunc tty_unlock(void) __releases(tty_lock);
+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);
 
 /*
  * this shall be called only from where BTM is held (like close)
@@ -626,9 +631,9 @@ extern void __lockfunc tty_unlock(void) __releases(tty_lock);
 static inline void tty_wait_until_sent_from_close(struct tty_struct *tty,
                long timeout)
 {
-       tty_unlock(); /* tty->ops->close holds the BTM, drop it while waiting */
+       tty_unlock(tty); /* tty->ops->close holds the BTM, drop it while waiting */
        tty_wait_until_sent(tty, timeout);
-       tty_lock();
+       tty_lock(tty);
 }
 
 /*
@@ -643,16 +648,16 @@ static inline void tty_wait_until_sent_from_close(struct tty_struct *tty,
  *
  * Do not use in new code.
  */
-#define wait_event_interruptible_tty(wq, condition)                    \
+#define wait_event_interruptible_tty(tty, wq, condition)               \
 ({                                                                     \
        int __ret = 0;                                                  \
        if (!(condition)) {                                             \
-               __wait_event_interruptible_tty(wq, condition, __ret);   \
+               __wait_event_interruptible_tty(tty, wq, condition, __ret);      \
        }                                                               \
        __ret;                                                          \
 })
 
-#define __wait_event_interruptible_tty(wq, condition, ret)             \
+#define __wait_event_interruptible_tty(tty, wq, condition, ret)                \
 do {                                                                   \
        DEFINE_WAIT(__wait);                                            \
                                                                        \
@@ -661,9 +666,9 @@ do {                                                                        \
                if (condition)                                          \
                        break;                                          \
                if (!signal_pending(current)) {                         \
-                       tty_unlock();                                   \
+                       tty_unlock(tty);                                        \
                        schedule();                                     \
-                       tty_lock();                                     \
+                       tty_lock(tty);                                  \
                        continue;                                       \
                }                                                       \
                ret = -ERESTARTSYS;                                     \

diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index d1820ff14aee46cfc55cd1c169495004c3130818..aa5d73b786aca23793f7691bbab7f86ceb2e96d1 100644 (file)
--- a/net/bluetooth/rfcomm/tty.c
+++ b/net/bluetooth/rfcomm/tty.c
@@ -710,9 +710,9 @@ static int rfcomm_tty_open(struct tty_struct *tty, struct file *filp)
                        break;
                }
 
-               tty_unlock();
+               tty_unlock(tty);
                schedule();
-               tty_lock();
+               tty_lock(tty);
        }
        set_current_state(TASK_RUNNING);
        remove_wait_queue(&dev->wait, &wait);