Commit d29f3ef3 authored by Alan Cox's avatar Alan Cox Committed by Greg Kroah-Hartman

tty_lock: Localise the lock

In each remaining case the tty_lock is associated with a specific tty. This
means we can now lock on a per tty basis. We do need tty_lock_pair() for
the pty case. Uglier but still a step in the right direction.

[fixed up calls in 3 missing drivers - gregkh]
Signed-off-by: default avatarAlan Cox <alan@linux.intel.com>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d739e65b
......@@ -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",
info->line, state->count);
#endif
tty_unlock();
tty_unlock(tty);
schedule();
tty_lock();
tty_lock(tty);
}
current->state = TASK_RUNNING;
remove_wait_queue(&info->open_wait, &wait);
......
......@@ -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;
}
......@@ -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;
}
......
......@@ -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;
}
......
......@@ -1065,7 +1065,8 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
TRACE_L("read()");
tty_lock();
/* FIXME: should use a private lock */
tty_lock(tty);
pClient = findClient(pInfo, task_pid(current));
if (pClient) {
......@@ -1077,7 +1078,7 @@ 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 +1108,7 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
}
ret = -EPERM;
unlock:
tty_unlock();
tty_unlock(tty);
return ret;
}
......@@ -1156,7 +1157,7 @@ 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 +1176,7 @@ 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;
}
......
......@@ -47,6 +47,7 @@ static void pty_close(struct tty_struct *tty, struct file *filp)
wake_up_interruptible(&tty->read_wait);
wake_up_interruptible(&tty->write_wait);
tty->packet = 0;
/* Review - krefs on tty_link ?? */
if (!tty->link)
return;
tty->link->packet = 0;
......@@ -62,9 +63,7 @@ static void pty_close(struct tty_struct *tty, struct file *filp)
mutex_unlock(&devpts_mutex);
}
#endif
tty_unlock();
tty_vhangup(tty->link);
tty_lock();
}
}
......@@ -622,26 +621,29 @@ static int ptmx_open(struct inode *inode, struct file *filp)
return retval;
/* find a device that is not in use. */
tty_lock();
mutex_lock(&devpts_mutex);
index = devpts_new_index(inode);
tty_unlock();
if (index < 0) {
retval = index;
goto err_file;
}
mutex_unlock(&devpts_mutex);
mutex_lock(&tty_mutex);
mutex_lock(&devpts_mutex);
tty = tty_init_dev(ptm_driver, index);
mutex_unlock(&devpts_mutex);
tty_lock();
mutex_unlock(&tty_mutex);
if (IS_ERR(tty)) {
retval = PTR_ERR(tty);
goto out;
}
/* The tty returned here is locked so we can safely
drop the mutex */
mutex_unlock(&devpts_mutex);
mutex_unlock(&tty_mutex);
set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
tty_add_file(tty, filp);
......@@ -654,16 +656,17 @@ static int ptmx_open(struct inode *inode, struct file *filp)
if (retval)
goto err_release;
tty_unlock();
tty_unlock(tty);
return 0;
err_release:
tty_unlock();
tty_unlock(tty);
tty_release(inode, filp);
return retval;
out:
mutex_unlock(&tty_mutex);
devpts_kill_index(inode, index);
tty_unlock();
err_file:
mutex_unlock(&devpts_mutex);
tty_free_file(filp);
return retval;
}
......
......@@ -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);
......
......@@ -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);
......
......@@ -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);
......
......@@ -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);
......
......@@ -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;
......@@ -1415,9 +1417,11 @@ 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:
......@@ -1426,6 +1430,7 @@ 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);
......@@ -1628,7 +1633,7 @@ 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);
......@@ -1637,10 +1642,11 @@ 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;
}
......@@ -1652,7 +1658,7 @@ 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
......@@ -1675,7 +1681,7 @@ 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));
......@@ -1706,7 +1712,7 @@ 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();
}
......@@ -1769,7 +1775,7 @@ 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;
}
......@@ -1782,14 +1788,16 @@ 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;
}
......@@ -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.
* 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)
......@@ -1916,8 +1927,7 @@ 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);
......@@ -1938,17 +1948,19 @@ 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;
}
......@@ -1977,7 +1989,7 @@ 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;
......@@ -1989,17 +2001,15 @@ 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 &&
......@@ -2007,11 +2017,10 @@ 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))
......@@ -2094,10 +2103,13 @@ 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;
}
......@@ -2934,6 +2946,7 @@ 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);
......
......@@ -567,7 +567,7 @@ 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.
......@@ -581,12 +581,12 @@ 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
......@@ -594,7 +594,7 @@ 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);
/*
......@@ -604,10 +604,10 @@ 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);
}
......@@ -622,7 +622,7 @@ 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
......@@ -649,7 +649,7 @@ 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 */
......@@ -664,7 +664,7 @@ 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;
}
......@@ -707,7 +707,7 @@ enable:
if (o_work)
schedule_work(&o_tty->buf.work);
mutex_unlock(&tty->ldisc_mutex);
tty_unlock();
tty_unlock(tty);
return retval;
}
......@@ -815,11 +815,11 @@ 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
......@@ -830,7 +830,7 @@ 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;
......@@ -911,10 +911,10 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
* race with the set_ldisc code path.
*/
tty_unlock();
tty_unlock(tty);
tty_ldisc_halt(tty);
tty_ldisc_flush_works(tty);
tty_lock();
tty_lock(tty);
mutex_lock(&tty->ldisc_mutex);
/*
......
......@@ -4,29 +4,59 @@
#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 */
/*
* 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);
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(tty2);
} else {
if (tty2 && tty2 != tty)
tty_lock(tty2);