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tty_lock: Localise the lock

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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>
This commit is contained in:
Alan Cox 2012-05-03 22:24:08 +01:00 committed by Greg Kroah-Hartman
parent d739e65bb2
commit d29f3ef39b
15 changed files with 155 additions and 103 deletions
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4
drivers/staging/serial/68360serial.c
View file

@ -1859,9 +1859,9 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp,
printk("block_til_ready blocking: ttys%d, count = %d\n", printk("block_til_ready blocking: ttys%d, count = %d\n",
info->line, state->count); info->line, state->count);
#endif #endif
tty_unlock(); tty_unlock(tty);
schedule(); schedule();
tty_lock(); tty_lock(tty);
} }
current->state = TASK_RUNNING; current->state = TASK_RUNNING;
remove_wait_queue(&info->open_wait, &wait); remove_wait_queue(&info->open_wait, &wait);

12
drivers/tty/amiserial.c
View file

@ -1033,7 +1033,7 @@ static int get_serial_info(struct tty_struct *tty, struct serial_state *state,
if (!retinfo) if (!retinfo)
return -EFAULT; return -EFAULT;
memset(&tmp, 0, sizeof(tmp)); memset(&tmp, 0, sizeof(tmp));
tty_lock(); tty_lock(tty);
tmp.line = tty->index; tmp.line = tty->index;
tmp.port = state->port; tmp.port = state->port;
tmp.flags = state->tport.flags; 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.close_delay = state->tport.close_delay;
tmp.closing_wait = state->tport.closing_wait; tmp.closing_wait = state->tport.closing_wait;
tmp.custom_divisor = state->custom_divisor; tmp.custom_divisor = state->custom_divisor;
tty_unlock(); tty_unlock(tty);
if (copy_to_user(retinfo,&tmp,sizeof(*retinfo))) if (copy_to_user(retinfo,&tmp,sizeof(*retinfo)))
return -EFAULT; return -EFAULT;
return 0; 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))) if (copy_from_user(&new_serial,new_info,sizeof(new_serial)))
return -EFAULT; return -EFAULT;
tty_lock(); tty_lock(tty);
change_spd = ((new_serial.flags ^ port->flags) & ASYNC_SPD_MASK) || change_spd = ((new_serial.flags ^ port->flags) & ASYNC_SPD_MASK) ||
new_serial.custom_divisor != state->custom_divisor; new_serial.custom_divisor != state->custom_divisor;
if (new_serial.irq || new_serial.port != state->port || if (new_serial.irq || new_serial.port != state->port ||
new_serial.xmit_fifo_size != state->xmit_fifo_size) { new_serial.xmit_fifo_size != state->xmit_fifo_size) {
tty_unlock(); tty_unlock(tty);
return -EINVAL; return -EINVAL;
} }
@ -1084,7 +1084,7 @@ static int set_serial_info(struct tty_struct *tty, struct serial_state *state,
} }
if (new_serial.baud_base < 9600) { if (new_serial.baud_base < 9600) {
tty_unlock(); tty_unlock(tty);
return -EINVAL; return -EINVAL;
} }
@ -1116,7 +1116,7 @@ static int set_serial_info(struct tty_struct *tty, struct serial_state *state,
} }
} else } else
retval = startup(tty, state); retval = startup(tty, state);
tty_unlock(); tty_unlock(tty);
return retval; return retval;
} }

2
drivers/tty/cyclades.c
View 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 the port is the middle of closing, bail out now
*/ */
if (tty_hung_up_p(filp) || (info->port.flags & ASYNC_CLOSING)) { 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)); !(info->port.flags & ASYNC_CLOSING));
return (info->port.flags & ASYNC_HUP_NOTIFY) ? -EAGAIN: -ERESTARTSYS; return (info->port.flags & ASYNC_HUP_NOTIFY) ? -EAGAIN: -ERESTARTSYS;
} }

11
drivers/tty/n_r3964.c
View file

@ -1065,7 +1065,8 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
TRACE_L("read()"); TRACE_L("read()");
tty_lock(); /* FIXME: should use a private lock */
tty_lock(tty);
pClient = findClient(pInfo, task_pid(current)); pClient = findClient(pInfo, task_pid(current));
if (pClient) { if (pClient) {
@ -1077,7 +1078,7 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
goto unlock; goto unlock;
} }
/* block until there is a message: */ /* 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))); (pMsg = remove_msg(pInfo, pClient)));
} }
@ -1107,7 +1108,7 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
} }
ret = -EPERM; ret = -EPERM;
unlock: unlock:
tty_unlock(); tty_unlock(tty);
return ret; return ret;
} }
@ -1156,7 +1157,7 @@ static ssize_t r3964_write(struct tty_struct *tty, struct file *file,
pHeader->locks = 0; pHeader->locks = 0;
pHeader->owner = NULL; pHeader->owner = NULL;
tty_lock(); tty_lock(tty);
pClient = findClient(pInfo, task_pid(current)); pClient = findClient(pInfo, task_pid(current));
if (pClient) { if (pClient) {
@ -1175,7 +1176,7 @@ static ssize_t r3964_write(struct tty_struct *tty, struct file *file,
add_tx_queue(pInfo, pHeader); add_tx_queue(pInfo, pHeader);
trigger_transmit(pInfo); trigger_transmit(pInfo);
tty_unlock(); tty_unlock(tty);
return 0; return 0;
} }

23
drivers/tty/pty.c
View file

@ -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->read_wait);
wake_up_interruptible(&tty->write_wait); wake_up_interruptible(&tty->write_wait);
tty->packet = 0; tty->packet = 0;
/* Review - krefs on tty_link ?? */
if (!tty->link) if (!tty->link)
return; return;
tty->link->packet = 0; tty->link->packet = 0;
@ -62,9 +63,7 @@ static void pty_close(struct tty_struct *tty, struct file *filp)
mutex_unlock(&devpts_mutex); mutex_unlock(&devpts_mutex);
} }
#endif #endif
tty_unlock();
tty_vhangup(tty->link); tty_vhangup(tty->link);
tty_lock();
} }
} }
@ -622,26 +621,29 @@ static int ptmx_open(struct inode *inode, struct file *filp)
return retval; return retval;
/* find a device that is not in use. */ /* find a device that is not in use. */
tty_lock(); mutex_lock(&devpts_mutex);
index = devpts_new_index(inode); index = devpts_new_index(inode);
tty_unlock();
if (index < 0) { if (index < 0) {
retval = index; retval = index;
goto err_file; goto err_file;
} }
mutex_unlock(&devpts_mutex);
mutex_lock(&tty_mutex); mutex_lock(&tty_mutex);
mutex_lock(&devpts_mutex); mutex_lock(&devpts_mutex);
tty = tty_init_dev(ptm_driver, index); tty = tty_init_dev(ptm_driver, index);
mutex_unlock(&devpts_mutex);
tty_lock();
mutex_unlock(&tty_mutex);
if (IS_ERR(tty)) { if (IS_ERR(tty)) {
retval = PTR_ERR(tty); retval = PTR_ERR(tty);
goto out; 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 */ set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
tty_add_file(tty, filp); tty_add_file(tty, filp);
@ -654,16 +656,17 @@ static int ptmx_open(struct inode *inode, struct file *filp)
if (retval) if (retval)
goto err_release; goto err_release;
tty_unlock(); tty_unlock(tty);
return 0; return 0;
err_release: err_release:
tty_unlock(); tty_unlock(tty);
tty_release(inode, filp); tty_release(inode, filp);
return retval; return retval;
out: out:
mutex_unlock(&tty_mutex);
devpts_kill_index(inode, index); devpts_kill_index(inode, index);
tty_unlock();
err_file: err_file:
mutex_unlock(&devpts_mutex);
tty_free_file(filp); tty_free_file(filp);
return retval; return retval;
} }

4
drivers/tty/serial/crisv10.c
View file

@ -4052,9 +4052,9 @@ block_til_ready(struct tty_struct *tty, struct file * filp,
printk("block_til_ready blocking: ttyS%d, count = %d\n", printk("block_til_ready blocking: ttyS%d, count = %d\n",
info->line, info->count); info->line, info->count);
#endif #endif
tty_unlock(); tty_unlock(tty);
schedule(); schedule();
tty_lock(); tty_lock(tty);
} }
set_current_state(TASK_RUNNING); set_current_state(TASK_RUNNING);
remove_wait_queue(&info->open_wait, &wait); remove_wait_queue(&info->open_wait, &wait);

4
drivers/tty/synclink.c
View 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", printk("%s(%d):block_til_ready blocking on %s count=%d\n",
__FILE__,__LINE__, tty->driver->name, port->count ); __FILE__,__LINE__, tty->driver->name, port->count );
tty_unlock(); tty_unlock(tty);
schedule(); schedule();
tty_lock(); tty_lock(tty);
} }
set_current_state(TASK_RUNNING); set_current_state(TASK_RUNNING);

4
drivers/tty/synclink_gt.c
View 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)); DBGINFO(("%s block_til_ready wait\n", tty->driver->name));
tty_unlock(); tty_unlock(tty);
schedule(); schedule();
tty_lock(); tty_lock(tty);
} }
set_current_state(TASK_RUNNING); set_current_state(TASK_RUNNING);

4
drivers/tty/synclinkmp.c
View 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", printk("%s(%d):%s block_til_ready() count=%d\n",
__FILE__,__LINE__, tty->driver->name, port->count ); __FILE__,__LINE__, tty->driver->name, port->count );
tty_unlock(); tty_unlock(tty);
schedule(); schedule();
tty_lock(); tty_lock(tty);
} }
set_current_state(TASK_RUNNING); set_current_state(TASK_RUNNING);

67
drivers/tty/tty_io.c
View file

@ -185,6 +185,7 @@ void free_tty_struct(struct tty_struct *tty)
put_device(tty->dev); put_device(tty->dev);
kfree(tty->write_buf); kfree(tty->write_buf);
tty_buffer_free_all(tty); tty_buffer_free_all(tty);
tty->magic = 0xDEADDEAD;
kfree(tty); kfree(tty);
} }
@ -573,7 +574,7 @@ void __tty_hangup(struct tty_struct *tty)
} }
spin_unlock(&redirect_lock); spin_unlock(&redirect_lock);
tty_lock(); tty_lock(tty);
/* some functions below drop BTM, so we need this bit */ /* some functions below drop BTM, so we need this bit */
set_bit(TTY_HUPPING, &tty->flags); set_bit(TTY_HUPPING, &tty->flags);
@ -666,7 +667,7 @@ void __tty_hangup(struct tty_struct *tty)
clear_bit(TTY_HUPPING, &tty->flags); clear_bit(TTY_HUPPING, &tty->flags);
tty_ldisc_enable(tty); tty_ldisc_enable(tty);
tty_unlock(); tty_unlock(tty);
if (f) if (f)
fput(f); fput(f);
@ -1103,12 +1104,12 @@ void tty_write_message(struct tty_struct *tty, char *msg)
{ {
if (tty) { if (tty) {
mutex_lock(&tty->atomic_write_lock); mutex_lock(&tty->atomic_write_lock);
tty_lock(); tty_lock(tty);
if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags)) { if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags)) {
tty_unlock(); tty_unlock(tty);
tty->ops->write(tty, msg, strlen(msg)); tty->ops->write(tty, msg, strlen(msg));
} else } else
tty_unlock(); tty_unlock(tty);
tty_write_unlock(tty); tty_write_unlock(tty);
} }
return; return;
@ -1403,6 +1404,7 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
} }
initialize_tty_struct(tty, driver, idx); initialize_tty_struct(tty, driver, idx);
tty_lock(tty);
retval = tty_driver_install_tty(driver, tty); retval = tty_driver_install_tty(driver, tty);
if (retval < 0) if (retval < 0)
goto err_deinit_tty; goto err_deinit_tty;
@ -1415,9 +1417,11 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
retval = tty_ldisc_setup(tty, tty->link); retval = tty_ldisc_setup(tty, tty->link);
if (retval) if (retval)
goto err_release_tty; goto err_release_tty;
/* Return the tty locked so that it cannot vanish under the caller */
return tty; return tty;
err_deinit_tty: err_deinit_tty:
tty_unlock(tty);
deinitialize_tty_struct(tty); deinitialize_tty_struct(tty);
free_tty_struct(tty); free_tty_struct(tty);
err_module_put: err_module_put:
@ -1426,6 +1430,7 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
/* call the tty release_tty routine to clean out this slot */ /* call the tty release_tty routine to clean out this slot */
err_release_tty: err_release_tty:
tty_unlock(tty);
printk_ratelimited(KERN_INFO "tty_init_dev: ldisc open failed, " printk_ratelimited(KERN_INFO "tty_init_dev: ldisc open failed, "
"clearing slot %d\n", idx); "clearing slot %d\n", idx);
release_tty(tty, idx); release_tty(tty, idx);
@ -1628,7 +1633,7 @@ int tty_release(struct inode *inode, struct file *filp)
if (tty_paranoia_check(tty, inode, __func__)) if (tty_paranoia_check(tty, inode, __func__))
return 0; return 0;
tty_lock(); tty_lock(tty);
check_tty_count(tty, __func__); check_tty_count(tty, __func__);
__tty_fasync(-1, filp, 0); __tty_fasync(-1, filp, 0);
@ -1637,10 +1642,11 @@ int tty_release(struct inode *inode, struct file *filp)
pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY && pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER); tty->driver->subtype == PTY_TYPE_MASTER);
devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0; devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
/* Review: parallel close */
o_tty = tty->link; o_tty = tty->link;
if (tty_release_checks(tty, o_tty, idx)) { if (tty_release_checks(tty, o_tty, idx)) {
tty_unlock(); tty_unlock(tty);
return 0; return 0;
} }
@ -1652,7 +1658,7 @@ int tty_release(struct inode *inode, struct file *filp)
if (tty->ops->close) if (tty->ops->close)
tty->ops->close(tty, filp); tty->ops->close(tty, filp);
tty_unlock(); tty_unlock(tty);
/* /*
* Sanity check: if tty->count is going to zero, there shouldn't be * 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 * any waiters on tty->read_wait or tty->write_wait. We test the
@ -1675,7 +1681,7 @@ int tty_release(struct inode *inode, struct file *filp)
opens on /dev/tty */ opens on /dev/tty */
mutex_lock(&tty_mutex); mutex_lock(&tty_mutex);
tty_lock(); tty_lock_pair(tty, o_tty);
tty_closing = tty->count <= 1; tty_closing = tty->count <= 1;
o_tty_closing = o_tty && o_tty_closing = o_tty &&
(o_tty->count <= (pty_master ? 1 : 0)); (o_tty->count <= (pty_master ? 1 : 0));
@ -1706,7 +1712,7 @@ int tty_release(struct inode *inode, struct file *filp)
printk(KERN_WARNING "%s: %s: read/write wait queue active!\n", printk(KERN_WARNING "%s: %s: read/write wait queue active!\n",
__func__, tty_name(tty, buf)); __func__, tty_name(tty, buf));
tty_unlock(); tty_unlock_pair(tty, o_tty);
mutex_unlock(&tty_mutex); mutex_unlock(&tty_mutex);
schedule(); schedule();
} }
@ -1769,7 +1775,7 @@ int tty_release(struct inode *inode, struct file *filp)
/* check whether both sides are closing ... */ /* check whether both sides are closing ... */
if (!tty_closing || (o_tty && !o_tty_closing)) { if (!tty_closing || (o_tty && !o_tty_closing)) {
tty_unlock(); tty_unlock_pair(tty, o_tty);
return 0; return 0;
} }
@ -1782,14 +1788,16 @@ int tty_release(struct inode *inode, struct file *filp)
tty_ldisc_release(tty, o_tty); tty_ldisc_release(tty, o_tty);
/* /*
* The release_tty function takes care of the details of clearing * 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); release_tty(tty, idx);
tty_unlock_pair(tty, o_tty);
/* Make this pty number available for reallocation */ /* Make this pty number available for reallocation */
if (devpts) if (devpts)
devpts_kill_index(inode, idx); devpts_kill_index(inode, idx);
tty_unlock();
return 0; return 0;
} }
@ -1893,6 +1901,9 @@ 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. * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
* tty->count should protect the rest. * tty->count should protect the rest.
* ->siglock protects ->signal/->sighand * ->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) static int tty_open(struct inode *inode, struct file *filp)
@ -1916,8 +1927,7 @@ static int tty_open(struct inode *inode, struct file *filp)
retval = 0; retval = 0;
mutex_lock(&tty_mutex); mutex_lock(&tty_mutex);
tty_lock(); /* This is protected by the tty_mutex */
tty = tty_open_current_tty(device, filp); tty = tty_open_current_tty(device, filp);
if (IS_ERR(tty)) { if (IS_ERR(tty)) {
retval = PTR_ERR(tty); retval = PTR_ERR(tty);
@ -1938,17 +1948,19 @@ static int tty_open(struct inode *inode, struct file *filp)
} }
if (tty) { if (tty) {
tty_lock(tty);
retval = tty_reopen(tty); retval = tty_reopen(tty);
if (retval) if (retval < 0) {
tty_unlock(tty);
tty = ERR_PTR(retval); tty = ERR_PTR(retval);
} else }
} else /* Returns with the tty_lock held for now */
tty = tty_init_dev(driver, index); tty = tty_init_dev(driver, index);
mutex_unlock(&tty_mutex); mutex_unlock(&tty_mutex);
if (driver) if (driver)
tty_driver_kref_put(driver); tty_driver_kref_put(driver);
if (IS_ERR(tty)) { if (IS_ERR(tty)) {
tty_unlock();
retval = PTR_ERR(tty); retval = PTR_ERR(tty);
goto err_file; goto err_file;
} }
@ -1977,7 +1989,7 @@ static int tty_open(struct inode *inode, struct file *filp)
printk(KERN_DEBUG "%s: error %d in opening %s...\n", __func__, printk(KERN_DEBUG "%s: error %d in opening %s...\n", __func__,
retval, tty->name); retval, tty->name);
#endif #endif
tty_unlock(); /* need to call tty_release without BTM */ tty_unlock(tty); /* need to call tty_release without BTM */
tty_release(inode, filp); tty_release(inode, filp);
if (retval != -ERESTARTSYS) if (retval != -ERESTARTSYS)
return retval; return retval;
@ -1989,17 +2001,15 @@ static int tty_open(struct inode *inode, struct file *filp)
/* /*
* Need to reset f_op in case a hangup happened. * Need to reset f_op in case a hangup happened.
*/ */
tty_lock();
if (filp->f_op == &hung_up_tty_fops) if (filp->f_op == &hung_up_tty_fops)
filp->f_op = &tty_fops; filp->f_op = &tty_fops;
tty_unlock();
goto retry_open; goto retry_open;
} }
tty_unlock(); tty_unlock(tty);
mutex_lock(&tty_mutex); mutex_lock(&tty_mutex);
tty_lock(); tty_lock(tty);
spin_lock_irq(&current->sighand->siglock); spin_lock_irq(&current->sighand->siglock);
if (!noctty && if (!noctty &&
current->signal->leader && current->signal->leader &&
@ -2007,11 +2017,10 @@ static int tty_open(struct inode *inode, struct file *filp)
tty->session == NULL) tty->session == NULL)
__proc_set_tty(current, tty); __proc_set_tty(current, tty);
spin_unlock_irq(&current->sighand->siglock); spin_unlock_irq(&current->sighand->siglock);
tty_unlock(); tty_unlock(tty);
mutex_unlock(&tty_mutex); mutex_unlock(&tty_mutex);
return 0; return 0;
err_unlock: err_unlock:
tty_unlock();
mutex_unlock(&tty_mutex); mutex_unlock(&tty_mutex);
/* after locks to avoid deadlock */ /* after locks to avoid deadlock */
if (!IS_ERR_OR_NULL(driver)) if (!IS_ERR_OR_NULL(driver))
@ -2094,10 +2103,13 @@ static int __tty_fasync(int fd, struct file *filp, int on)
static int tty_fasync(int fd, struct file *filp, int on) static int tty_fasync(int fd, struct file *filp, int on)
{ {
struct tty_struct *tty = file_tty(filp);
int retval; int retval;
tty_lock();
tty_lock(tty);
retval = __tty_fasync(fd, filp, on); retval = __tty_fasync(fd, filp, on);
tty_unlock(); tty_unlock(tty);
return retval; return retval;
} }
@ -2934,6 +2946,7 @@ void initialize_tty_struct(struct tty_struct *tty,
tty->pgrp = NULL; tty->pgrp = NULL;
tty->overrun_time = jiffies; tty->overrun_time = jiffies;
tty_buffer_init(tty); tty_buffer_init(tty);
mutex_init(&tty->legacy_mutex);
mutex_init(&tty->termios_mutex); mutex_init(&tty->termios_mutex);
mutex_init(&tty->ldisc_mutex); mutex_init(&tty->ldisc_mutex);
init_waitqueue_head(&tty->write_wait); init_waitqueue_head(&tty->write_wait);

30
drivers/tty/tty_ldisc.c
View file

@ -567,7 +567,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
if (IS_ERR(new_ldisc)) if (IS_ERR(new_ldisc))
return PTR_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 * We need to look at the tty locking here for pty/tty pairs
* when both sides try to change in parallel. * when both sides try to change in parallel.
@ -581,12 +581,12 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
*/ */
if (tty->ldisc->ops->num == ldisc) { if (tty->ldisc->ops->num == ldisc) {
tty_unlock(); tty_unlock(tty);
tty_ldisc_put(new_ldisc); tty_ldisc_put(new_ldisc);
return 0; return 0;
} }
tty_unlock(); tty_unlock(tty);
/* /*
* Problem: What do we do if this blocks ? * Problem: What do we do if this blocks ?
* We could deadlock here * We could deadlock here
@ -594,7 +594,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
tty_wait_until_sent(tty, 0); tty_wait_until_sent(tty, 0);
tty_lock(); tty_lock(tty);
mutex_lock(&tty->ldisc_mutex); mutex_lock(&tty->ldisc_mutex);
/* /*
@ -604,10 +604,10 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
while (test_bit(TTY_LDISC_CHANGING, &tty->flags)) { while (test_bit(TTY_LDISC_CHANGING, &tty->flags)) {
mutex_unlock(&tty->ldisc_mutex); mutex_unlock(&tty->ldisc_mutex);
tty_unlock(); tty_unlock(tty);
wait_event(tty_ldisc_wait, wait_event(tty_ldisc_wait,
test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0); test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0);
tty_lock(); tty_lock(tty);
mutex_lock(&tty->ldisc_mutex); mutex_lock(&tty->ldisc_mutex);
} }
@ -622,7 +622,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
o_ldisc = tty->ldisc; o_ldisc = tty->ldisc;
tty_unlock(); tty_unlock(tty);
/* /*
* Make sure we don't change while someone holds a * Make sure we don't change while someone holds a
* reference to the line discipline. The TTY_LDISC bit * reference to the line discipline. The TTY_LDISC bit
@ -649,7 +649,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
retval = tty_ldisc_wait_idle(tty, 5 * HZ); retval = tty_ldisc_wait_idle(tty, 5 * HZ);
tty_lock(); tty_lock(tty);
mutex_lock(&tty->ldisc_mutex); mutex_lock(&tty->ldisc_mutex);
/* handle wait idle failure locked */ /* handle wait idle failure locked */
@ -664,7 +664,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
clear_bit(TTY_LDISC_CHANGING, &tty->flags); clear_bit(TTY_LDISC_CHANGING, &tty->flags);
mutex_unlock(&tty->ldisc_mutex); mutex_unlock(&tty->ldisc_mutex);
tty_ldisc_put(new_ldisc); tty_ldisc_put(new_ldisc);
tty_unlock(); tty_unlock(tty);
return -EIO; return -EIO;
} }
@ -707,7 +707,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
if (o_work) if (o_work)
schedule_work(&o_tty->buf.work); schedule_work(&o_tty->buf.work);
mutex_unlock(&tty->ldisc_mutex); mutex_unlock(&tty->ldisc_mutex);
tty_unlock(); tty_unlock(tty);
return retval; return retval;
} }
@ -815,11 +815,11 @@ void tty_ldisc_hangup(struct tty_struct *tty)
* need to wait for another function taking the BTM * need to wait for another function taking the BTM
*/ */
clear_bit(TTY_LDISC, &tty->flags); clear_bit(TTY_LDISC, &tty->flags);
tty_unlock(); tty_unlock(tty);
cancel_work_sync(&tty->buf.work); cancel_work_sync(&tty->buf.work);
mutex_unlock(&tty->ldisc_mutex); mutex_unlock(&tty->ldisc_mutex);
retry: retry:
tty_lock(); tty_lock(tty);
mutex_lock(&tty->ldisc_mutex); mutex_lock(&tty->ldisc_mutex);
/* At this point we have a closed ldisc and we want to /* At this point we have a closed ldisc and we want to
@ -830,7 +830,7 @@ void tty_ldisc_hangup(struct tty_struct *tty)
if (atomic_read(&tty->ldisc->users) != 1) { if (atomic_read(&tty->ldisc->users) != 1) {
char cur_n[TASK_COMM_LEN], tty_n[64]; char cur_n[TASK_COMM_LEN], tty_n[64];
long timeout = 3 * HZ; long timeout = 3 * HZ;
tty_unlock(); tty_unlock(tty);
while (tty_ldisc_wait_idle(tty, timeout) == -EBUSY) { while (tty_ldisc_wait_idle(tty, timeout) == -EBUSY) {
timeout = MAX_SCHEDULE_TIMEOUT; timeout = MAX_SCHEDULE_TIMEOUT;
@ -911,10 +911,10 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
* race with the set_ldisc code path. * race with the set_ldisc code path.
*/ */
tty_unlock(); tty_unlock(tty);
tty_ldisc_halt(tty); tty_ldisc_halt(tty);
tty_ldisc_flush_works(tty); tty_ldisc_flush_works(tty);
tty_lock(); tty_lock(tty);
mutex_lock(&tty->ldisc_mutex); mutex_lock(&tty->ldisc_mutex);
/* /*

60
drivers/tty/tty_mutex.c
View file

@ -4,29 +4,59 @@
#include <linux/semaphore.h> #include <linux/semaphore.h>
#include <linux/sched.h> #include <linux/sched.h>
/* /* Legacy tty mutex glue */
* 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. * Getting the big tty mutex.
*/ */
void __lockfunc tty_lock(void)
void __lockfunc tty_lock(struct tty_struct *tty)
{ {
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(&tty->legacy_mutex);
} }
EXPORT_SYMBOL(tty_lock); 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); 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(tty2);
} else {
if (tty2 && tty2 != tty)
tty_lock(tty2);
tty_lock(tty);
}
}
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);

6
drivers/tty/tty_port.c
View 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 */ /* block if port is in the process of being closed */
if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) { 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)); !(port->flags & ASYNC_CLOSING));
if (port->flags & ASYNC_HUP_NOTIFY) if (port->flags & ASYNC_HUP_NOTIFY)
return -EAGAIN; return -EAGAIN;
@ -296,9 +296,9 @@ int tty_port_block_til_ready(struct tty_port *port,
retval = -ERESTARTSYS; retval = -ERESTARTSYS;
break; break;
} }
tty_unlock(); tty_unlock(tty);
schedule(); schedule();
tty_lock(); tty_lock(tty);
} }
finish_wait(&port->open_wait, &wait); finish_wait(&port->open_wait, &wait);

23
include/linux/tty.h
View file

@ -268,6 +268,7 @@ struct tty_struct {
struct mutex ldisc_mutex; struct mutex ldisc_mutex;
struct tty_ldisc *ldisc; struct tty_ldisc *ldisc;
struct mutex legacy_mutex;
struct mutex termios_mutex; struct mutex termios_mutex;
spinlock_t ctrl_lock; spinlock_t ctrl_lock;
/* Termios values are protected by the termios mutex */ /* Termios values are protected by the termios mutex */
@ -605,8 +606,12 @@ extern long vt_compat_ioctl(struct tty_struct *tty,
/* tty_mutex.c */ /* tty_mutex.c */
/* functions for preparation of BKL removal */ /* functions for preparation of BKL removal */
extern void __lockfunc tty_lock(void) __acquires(tty_lock); extern void __lockfunc tty_lock(struct tty_struct *tty);
extern void __lockfunc tty_unlock(void) __releases(tty_lock); 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) * this shall be called only from where BTM is held (like close)
@ -621,9 +626,9 @@ extern void __lockfunc tty_unlock(void) __releases(tty_lock);
static inline void tty_wait_until_sent_from_close(struct tty_struct *tty, static inline void tty_wait_until_sent_from_close(struct tty_struct *tty,
long timeout) 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_wait_until_sent(tty, timeout);
tty_lock(); tty_lock(tty);
} }
/* /*
@ -638,16 +643,16 @@ static inline void tty_wait_until_sent_from_close(struct tty_struct *tty,
* *
* Do not use in new code. * Do not use in new code.
*/ */
#define wait_event_interruptible_tty(wq, condition) \ #define wait_event_interruptible_tty(tty, wq, condition) \
({ \ ({ \
int __ret = 0; \ int __ret = 0; \
if (!(condition)) { \ if (!(condition)) { \
__wait_event_interruptible_tty(wq, condition, __ret); \ __wait_event_interruptible_tty(tty, wq, condition, __ret); \
} \ } \
__ret; \ __ret; \
}) })
#define __wait_event_interruptible_tty(wq, condition, ret) \ #define __wait_event_interruptible_tty(tty, wq, condition, ret) \
do { \ do { \
DEFINE_WAIT(__wait); \ DEFINE_WAIT(__wait); \
\ \
@ -656,9 +661,9 @@ do { \
if (condition) \ if (condition) \
break; \ break; \
if (!signal_pending(current)) { \ if (!signal_pending(current)) { \
tty_unlock(); \ tty_unlock(tty); \
schedule(); \ schedule(); \
tty_lock(); \ tty_lock(tty); \
continue; \ continue; \
} \ } \
ret = -ERESTARTSYS; \ ret = -ERESTARTSYS; \

4
net/bluetooth/rfcomm/tty.c
View file

@ -710,9 +710,9 @@ static int rfcomm_tty_open(struct tty_struct *tty, struct file *filp)
break; break;
} }
tty_unlock(); tty_unlock(tty);
schedule(); schedule();
tty_lock(); tty_lock(tty);
} }
set_current_state(TASK_RUNNING); set_current_state(TASK_RUNNING);
remove_wait_queue(&dev->wait, &wait); remove_wait_queue(&dev->wait, &wait);