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tty: push the BKL down into the handlers a bit
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Start trying to untangle the remaining BKL mess

Updated to fix missing unlock_kernel noted by Dan Carpenter

Signed-off-by: Alan "I must be out of my tree" Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Alan Cox authored and Greg Kroah-Hartman committed Dec 11, 2009
1 parent e8c6210 commit eeb89d9
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Showing 4 changed files with 95 additions and 63 deletions.
2 changes: 1 addition & 1 deletion drivers/char/pty.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -659,7 +659,7 @@ static int __ptmx_open(struct inode *inode, struct file *filp)
if (!retval)
return 0;
out1:
tty_release_dev(filp);
tty_release(inode, filp);
return retval;
out:
devpts_kill_index(inode, index);
Expand Down
141 changes: 80 additions & 61 deletions drivers/char/tty_io.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -142,7 +142,6 @@ ssize_t redirected_tty_write(struct file *, const char __user *,
size_t, loff_t *);
static unsigned int tty_poll(struct file *, poll_table *);
static int tty_open(struct inode *, struct file *);
static int tty_release(struct inode *, struct file *);
long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
#ifdef CONFIG_COMPAT
static long tty_compat_ioctl(struct file *file, unsigned int cmd,
Expand Down Expand Up @@ -1017,14 +1016,16 @@ static inline ssize_t do_tty_write(

void tty_write_message(struct tty_struct *tty, char *msg)
{
lock_kernel();
if (tty) {
mutex_lock(&tty->atomic_write_lock);
if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags))
lock_kernel();
if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags)) {
unlock_kernel();
tty->ops->write(tty, msg, strlen(msg));
} else
unlock_kernel();
tty_write_unlock(tty);
}
unlock_kernel();
return;
}

Expand Down Expand Up @@ -1202,14 +1203,21 @@ static int tty_driver_install_tty(struct tty_driver *driver,
struct tty_struct *tty)
{
int idx = tty->index;
int ret;

if (driver->ops->install)
return driver->ops->install(driver, tty);
if (driver->ops->install) {
lock_kernel();
ret = driver->ops->install(driver, tty);
unlock_kernel();
return ret;
}

if (tty_init_termios(tty) == 0) {
lock_kernel();
tty_driver_kref_get(driver);
tty->count++;
driver->ttys[idx] = tty;
unlock_kernel();
return 0;
}
return -ENOMEM;
Expand Down Expand Up @@ -1302,10 +1310,14 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
struct tty_struct *tty;
int retval;

lock_kernel();
/* Check if pty master is being opened multiple times */
if (driver->subtype == PTY_TYPE_MASTER &&
(driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok)
(driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
unlock_kernel();
return ERR_PTR(-EIO);
}
unlock_kernel();

/*
* First time open is complex, especially for PTY devices.
Expand Down Expand Up @@ -1335,8 +1347,9 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
* If we fail here just call release_tty to clean up. No need
* to decrement the use counts, as release_tty doesn't care.
*/

lock_kernel();
retval = tty_ldisc_setup(tty, tty->link);
unlock_kernel();
if (retval)
goto release_mem_out;
return tty;
Expand All @@ -1350,7 +1363,9 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
if (printk_ratelimit())
printk(KERN_INFO "tty_init_dev: ldisc open failed, "
"clearing slot %d\n", idx);
lock_kernel();
release_tty(tty, idx);
unlock_kernel();
return ERR_PTR(retval);
}

Expand Down Expand Up @@ -1464,28 +1479,38 @@ static void release_tty(struct tty_struct *tty, int idx)
tty_kref_put(tty);
}

/*
/**
* tty_release - vfs callback for close
* @inode: inode of tty
* @filp: file pointer for handle to tty
*
* Called the last time each file handle is closed that references
* this tty. There may however be several such references.
*
* Locking:
* Takes bkl. See tty_release_dev
*
* Even releasing the tty structures is a tricky business.. We have
* to be very careful that the structures are all released at the
* same time, as interrupts might otherwise get the wrong pointers.
*
* WSH 09/09/97: rewritten to avoid some nasty race conditions that could
* lead to double frees or releasing memory still in use.
*/
void tty_release_dev(struct file *filp)

int tty_release(struct inode *inode, struct file *filp)
{
struct tty_struct *tty, *o_tty;
int pty_master, tty_closing, o_tty_closing, do_sleep;
int devpts;
int idx;
char buf[64];
struct inode *inode;

inode = filp->f_path.dentry->d_inode;
tty = (struct tty_struct *)filp->private_data;
if (tty_paranoia_check(tty, inode, "tty_release_dev"))
return;
return 0;

lock_kernel();
check_tty_count(tty, "tty_release_dev");

tty_fasync(-1, filp, 0);
Expand All @@ -1500,19 +1525,22 @@ void tty_release_dev(struct file *filp)
if (idx < 0 || idx >= tty->driver->num) {
printk(KERN_DEBUG "tty_release_dev: bad idx when trying to "
"free (%s)\n", tty->name);
return;
unlock_kernel();
return 0;
}
if (!devpts) {
if (tty != tty->driver->ttys[idx]) {
unlock_kernel();
printk(KERN_DEBUG "tty_release_dev: driver.table[%d] not tty "
"for (%s)\n", idx, tty->name);
return;
return 0;
}
if (tty->termios != tty->driver->termios[idx]) {
unlock_kernel();
printk(KERN_DEBUG "tty_release_dev: driver.termios[%d] not termios "
"for (%s)\n",
idx, tty->name);
return;
return 0;
}
}
#endif
Expand All @@ -1526,26 +1554,30 @@ void tty_release_dev(struct file *filp)
if (tty->driver->other &&
!(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
if (o_tty != tty->driver->other->ttys[idx]) {
unlock_kernel();
printk(KERN_DEBUG "tty_release_dev: other->table[%d] "
"not o_tty for (%s)\n",
idx, tty->name);
return;
return 0 ;
}
if (o_tty->termios != tty->driver->other->termios[idx]) {
unlock_kernel();
printk(KERN_DEBUG "tty_release_dev: other->termios[%d] "
"not o_termios for (%s)\n",
idx, tty->name);
return;
return 0;
}
if (o_tty->link != tty) {
unlock_kernel();
printk(KERN_DEBUG "tty_release_dev: bad pty pointers\n");
return;
return 0;
}
}
#endif
if (tty->ops->close)
tty->ops->close(tty, filp);

unlock_kernel();
/*
* 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
Expand All @@ -1568,6 +1600,7 @@ void tty_release_dev(struct file *filp)
opens on /dev/tty */

mutex_lock(&tty_mutex);
lock_kernel();
tty_closing = tty->count <= 1;
o_tty_closing = o_tty &&
(o_tty->count <= (pty_master ? 1 : 0));
Expand Down Expand Up @@ -1598,6 +1631,7 @@ void tty_release_dev(struct file *filp)

printk(KERN_WARNING "tty_release_dev: %s: read/write wait queue "
"active!\n", tty_name(tty, buf));
unlock_kernel();
mutex_unlock(&tty_mutex);
schedule();
}
Expand Down Expand Up @@ -1661,8 +1695,10 @@ void tty_release_dev(struct file *filp)
mutex_unlock(&tty_mutex);

/* check whether both sides are closing ... */
if (!tty_closing || (o_tty && !o_tty_closing))
return;
if (!tty_closing || (o_tty && !o_tty_closing)) {
unlock_kernel();
return 0;
}

#ifdef TTY_DEBUG_HANGUP
printk(KERN_DEBUG "freeing tty structure...");
Expand All @@ -1680,10 +1716,12 @@ void tty_release_dev(struct file *filp)
/* Make this pty number available for reallocation */
if (devpts)
devpts_kill_index(inode, idx);
unlock_kernel();
return 0;
}

/**
* __tty_open - open a tty device
* tty_open - open a tty device
* @inode: inode of device file
* @filp: file pointer to tty
*
Expand All @@ -1703,7 +1741,7 @@ void tty_release_dev(struct file *filp)
* ->siglock protects ->signal/->sighand
*/

static int __tty_open(struct inode *inode, struct file *filp)
static int tty_open(struct inode *inode, struct file *filp)
{
struct tty_struct *tty = NULL;
int noctty, retval;
Expand All @@ -1720,10 +1758,12 @@ static int __tty_open(struct inode *inode, struct file *filp)
retval = 0;

mutex_lock(&tty_mutex);
lock_kernel();

if (device == MKDEV(TTYAUX_MAJOR, 0)) {
tty = get_current_tty();
if (!tty) {
unlock_kernel();
mutex_unlock(&tty_mutex);
return -ENXIO;
}
Expand Down Expand Up @@ -1755,12 +1795,14 @@ static int __tty_open(struct inode *inode, struct file *filp)
goto got_driver;
}
}
unlock_kernel();
mutex_unlock(&tty_mutex);
return -ENODEV;
}

driver = get_tty_driver(device, &index);
if (!driver) {
unlock_kernel();
mutex_unlock(&tty_mutex);
return -ENODEV;
}
Expand All @@ -1770,6 +1812,7 @@ static int __tty_open(struct inode *inode, struct file *filp)
tty = tty_driver_lookup_tty(driver, inode, index);

if (IS_ERR(tty)) {
unlock_kernel();
mutex_unlock(&tty_mutex);
return PTR_ERR(tty);
}
Expand All @@ -1784,8 +1827,10 @@ static int __tty_open(struct inode *inode, struct file *filp)

mutex_unlock(&tty_mutex);
tty_driver_kref_put(driver);
if (IS_ERR(tty))
if (IS_ERR(tty)) {
unlock_kernel();
return PTR_ERR(tty);
}

filp->private_data = tty;
file_move(filp, &tty->tty_files);
Expand Down Expand Up @@ -1813,11 +1858,15 @@ static int __tty_open(struct inode *inode, struct file *filp)
printk(KERN_DEBUG "error %d in opening %s...", retval,
tty->name);
#endif
tty_release_dev(filp);
if (retval != -ERESTARTSYS)
tty_release(inode, filp);
if (retval != -ERESTARTSYS) {
unlock_kernel();
return retval;
if (signal_pending(current))
}
if (signal_pending(current)) {
unlock_kernel();
return retval;
}
schedule();
/*
* Need to reset f_op in case a hangup happened.
Expand All @@ -1826,53 +1875,25 @@ static int __tty_open(struct inode *inode, struct file *filp)
filp->f_op = &tty_fops;
goto retry_open;
}
unlock_kernel();


mutex_lock(&tty_mutex);
lock_kernel();
spin_lock_irq(&current->sighand->siglock);
if (!noctty &&
current->signal->leader &&
!current->signal->tty &&
tty->session == NULL)
__proc_set_tty(current, tty);
spin_unlock_irq(&current->sighand->siglock);
unlock_kernel();
mutex_unlock(&tty_mutex);
return 0;
}

/* BKL pushdown: scary code avoidance wrapper */
static int tty_open(struct inode *inode, struct file *filp)
{
int ret;

lock_kernel();
ret = __tty_open(inode, filp);
unlock_kernel();
return ret;
}




/**
* tty_release - vfs callback for close
* @inode: inode of tty
* @filp: file pointer for handle to tty
*
* Called the last time each file handle is closed that references
* this tty. There may however be several such references.
*
* Locking:
* Takes bkl. See tty_release_dev
*/

static int tty_release(struct inode *inode, struct file *filp)
{
lock_kernel();
tty_release_dev(filp);
unlock_kernel();
return 0;
}

/**
* tty_poll - check tty status
* @filp: file being polled
Expand Down Expand Up @@ -2317,9 +2338,7 @@ static int tiocsetd(struct tty_struct *tty, int __user *p)
if (get_user(ldisc, p))
return -EFAULT;

lock_kernel();
ret = tty_set_ldisc(tty, ldisc);
unlock_kernel();

return ret;
}
Expand Down
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