[PATCH 51/76] tty: kref the tty driver object

Alan Cox
2008-10-05T16:23:36Z

drivers/char/ip2/ip2main.c | 6 +-
drivers/char/pty.c | 5 ++
drivers/char/tty_io.c | 110 ++++++++++++++++++++++++--------------------
drivers/net/wan/Kconfig | 2 -
include/linux/tty_driver.h | 15 ++++--
5 files changed, 80 insertions(+), 58 deletions(-)

diff --git a/drivers/char/ip2/ip2main.c b/drivers/char/ip2/ip2main.c
index 66f52a2..6774572 100644
--- a/drivers/char/ip2/ip2main.c
+++ b/drivers/char/ip2/ip2main.c
@@ -264,8 +264,8 @@ static int tracewrap;
/**********/

#if defined(MODULE) && defined(IP2DEBUG_OPEN)
-#define DBG_CNT(s) printk(KERN_DEBUG "(%s): [%x] refc=%d, ttyc=%d, modc=%x -> %s\n", \
- tty->name,(pCh->flags),ip2_tty_driver->refcount, \
+#define DBG_CNT(s) printk(KERN_DEBUG "(%s): [%x] ttyc=%d, modc=%x -> %s\n", \
+ tty->name,(pCh->flags), \
tty->count,/*GET_USE_COUNT(module)*/0,s)
#else
#define DBG_CNT(s)
@@ -2893,7 +2893,7 @@ ip2_ipl_ioctl (struct file *pFile, UINT cmd, ULONG arg )
case 13:
switch ( cmd ) {
case 64: /* Driver - ip2stat */
- rc = put_user(ip2_tty_driver->refcount, pIndex++ );
+ rc = put_user(-1, pIndex++ );
rc = put_user(irq_counter, pIndex++ );
rc = put_user(bh_counter, pIndex++ );
break;
diff --git a/drivers/char/pty.c b/drivers/char/pty.c
index 6e148ad..0fdfa05 100644
--- a/drivers/char/pty.c
+++ b/drivers/char/pty.c
@@ -571,8 +571,11 @@ static void __init unix98_pty_init(void)
if (tty_register_driver(pts_driver))
panic("Couldn't register Unix98 pts driver");

+ /* FIXME: WTF */
+#if 0
pty_table[1].data = &ptm_driver->refcount;
- register_sysctl_table(pty_root_table);
+#endif
+ register_sysctl_table(pty_root_table);

/* Now create the /dev/ptmx special device */
tty_default_fops(&ptmx_fops);
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index ac41af8..47aa437 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -276,7 +276,7 @@ static struct tty_driver *get_tty_driver(dev_t device, int *index)
if (device < base || device >= base + p->num)
continue;
*index = device - base;
- return p;
+ return tty_driver_kref_get(p);
}
return NULL;
}
@@ -320,7 +320,7 @@ struct tty_driver *tty_find_polling_driver(char *name, int *line)

if (tty_line >= 0 && tty_line <= p->num && p->ops &&
p->ops->poll_init && !p->ops->poll_init(p, tty_line, str)) {
- res = p;
+ res = tty_driver_kref_get(p);
*line = tty_line;
break;
}
@@ -1410,7 +1410,7 @@ int tty_init_dev(struct tty_driver *driver, int idx,
*o_ltp_loc = o_ltp;
o_tty->termios = *o_tp_loc;
o_tty->termios_locked = *o_ltp_loc;
- driver->other->refcount++;
+ tty_driver_kref_get(driver->other);
if (driver->subtype == PTY_TYPE_MASTER)
o_tty->count++;

@@ -1438,7 +1438,7 @@ int tty_init_dev(struct tty_driver *driver, int idx,
/* Compatibility until drivers always set this */
tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
- driver->refcount++;
+ tty_driver_kref_get(driver);
tty->count++;

/*
@@ -1530,8 +1530,7 @@ static void release_one_tty(struct kref *kref)
else
tty_shutdown(tty);
tty->magic = 0;
- /* FIXME: locking on tty->driver->refcount */
- tty->driver->refcount--;
+ tty_driver_kref_put(driver);
module_put(driver->owner);

file_list_lock();
@@ -1854,7 +1853,7 @@ retry_open:
mutex_unlock(&tty_mutex);
return -ENXIO;
}
- driver = tty->driver;
+ driver = tty_driver_kref_get(tty->driver);
index = tty->index;
filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
/* noctty = 1; */
@@ -1865,14 +1864,14 @@ retry_open:
#ifdef CONFIG_VT
if (device == MKDEV(TTY_MAJOR, 0)) {
extern struct tty_driver *console_driver;
- driver = console_driver;
+ driver = tty_driver_kref_get(console_driver);
index = fg_console;
noctty = 1;
goto got_driver;
}
#endif
if (device == MKDEV(TTYAUX_MAJOR, 1)) {
- driver = console_device(&index);
+ driver = tty_driver_kref_get(console_device(&index));
if (driver) {
/* Don't let /dev/console block */
filp->f_flags |= O_NONBLOCK;
@@ -1891,6 +1890,7 @@ retry_open:
got_driver:
retval = tty_init_dev(driver, index, &tty, 0);
mutex_unlock(&tty_mutex);
+ tty_driver_kref_put(driver);
if (retval)
return retval;

@@ -2866,7 +2866,6 @@ int tty_put_char(struct tty_struct *tty, unsigned char ch)
return tty->ops->put_char(tty, ch);
return tty->ops->write(tty, &ch, 1);
}
-
EXPORT_SYMBOL_GPL(tty_put_char);

struct class *tty_class;
@@ -2909,6 +2908,7 @@ struct device *tty_register_device(struct tty_driver *driver, unsigned index,

return device_create_drvdata(tty_class, device, dev, NULL, name);
}
+EXPORT_SYMBOL(tty_register_device);

/**
* tty_unregister_device - unregister a tty device
@@ -2926,8 +2926,6 @@ void tty_unregister_device(struct tty_driver *driver, unsigned index)
device_destroy(tty_class,
MKDEV(driver->major, driver->minor_start) + index);
}
-
-EXPORT_SYMBOL(tty_register_device);
EXPORT_SYMBOL(tty_unregister_device);

struct tty_driver *alloc_tty_driver(int lines)
@@ -2936,27 +2934,70 @@ struct tty_driver *alloc_tty_driver(int lines)

driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
if (driver) {
+ kref_init(&driver->kref);
driver->magic = TTY_DRIVER_MAGIC;
driver->num = lines;
/* later we'll move allocation of tables here */
}
return driver;
}
+EXPORT_SYMBOL(alloc_tty_driver);

-void put_tty_driver(struct tty_driver *driver)
+static void destruct_tty_driver(struct kref *kref)
{
+ struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
+ int i;
+ struct ktermios *tp;
+ void *p;
+
+ if (driver->flags & TTY_DRIVER_INSTALLED) {
+ /*
+ * Free the termios and termios_locked structures because
+ * we don't want to get memory leaks when modular tty
+ * drivers are removed from the kernel.
+ */
+ for (i = 0; i < driver->num; i++) {
+ tp = driver->termios[i];
+ if (tp) {
+ driver->termios[i] = NULL;
+ kfree(tp);
+ }
+ tp = driver->termios_locked[i];
+ if (tp) {
+ driver->termios_locked[i] = NULL;
+ kfree(tp);
+ }
+ if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
+ tty_unregister_device(driver, i);
+ }
+ p = driver->ttys;
+ proc_tty_unregister_driver(driver);
+ driver->ttys = NULL;
+ driver->termios = driver->termios_locked = NULL;
+ kfree(p);
+ cdev_del(&driver->cdev);
+ }
kfree(driver);
}

+void tty_driver_kref_put(struct tty_driver *driver)
+{
+ kref_put(&driver->kref, destruct_tty_driver);
+}
+EXPORT_SYMBOL(tty_driver_kref_put);
+
void tty_set_operations(struct tty_driver *driver,
const struct tty_operations *op)
{
driver->ops = op;
};
+EXPORT_SYMBOL(tty_set_operations);

-EXPORT_SYMBOL(alloc_tty_driver);
+void put_tty_driver(struct tty_driver *d)
+{
+ tty_driver_kref_put(d);
+}
EXPORT_SYMBOL(put_tty_driver);
-EXPORT_SYMBOL(tty_set_operations);

/*
* Called by a tty driver to register itself.
@@ -2968,9 +3009,6 @@ int tty_register_driver(struct tty_driver *driver)
dev_t dev;
void **p = NULL;

- if (driver->flags & TTY_DRIVER_INSTALLED)
- return 0;
-
if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
p = kzalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL);
if (!p)
@@ -3024,6 +3062,7 @@ int tty_register_driver(struct tty_driver *driver)
tty_register_device(driver, i, NULL);
}
proc_tty_register_driver(driver);
+ driver->flags |= TTY_DRIVER_INSTALLED;
return 0;
}

@@ -3034,46 +3073,19 @@ EXPORT_SYMBOL(tty_register_driver);
*/
int tty_unregister_driver(struct tty_driver *driver)
{
- int i;
- struct ktermios *tp;
- void *p;
-
+#if 0
+ /* FIXME */
if (driver->refcount)
return -EBUSY;
-
+#endif
unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
driver->num);
mutex_lock(&tty_mutex);
list_del(&driver->tty_drivers);
mutex_unlock(&tty_mutex);
-
- /*
- * Free the termios and termios_locked structures because
- * we don't want to get memory leaks when modular tty
- * drivers are removed from the kernel.
- */
- for (i = 0; i < driver->num; i++) {
- tp = driver->termios[i];
- if (tp) {
- driver->termios[i] = NULL;
- kfree(tp);
- }
- tp = driver->termios_locked[i];
- if (tp) {
- driver->termios_locked[i] = NULL;
- kfree(tp);
- }
- if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
- tty_unregister_device(driver, i);
- }
- p = driver->ttys;
- proc_tty_unregister_driver(driver);
- driver->ttys = NULL;
- driver->termios = driver->termios_locked = NULL;
- kfree(p);
- cdev_del(&driver->cdev);
return 0;
}
+
EXPORT_SYMBOL(tty_unregister_driver);

dev_t tty_devnum(struct tty_struct *tty)
diff --git a/drivers/net/wan/Kconfig b/drivers/net/wan/Kconfig
index 2ae2ec4..21efd99 100644
--- a/drivers/net/wan/Kconfig
+++ b/drivers/net/wan/Kconfig
@@ -205,7 +205,7 @@ config WANXL_BUILD_FIRMWARE

config PC300
tristate "Cyclades-PC300 support (RS-232/V.35, X.21, T1/E1 boards)"
- depends on HDLC && PCI
+ depends on HDLC && PCI && BROKEN
---help---
Driver for the Cyclades-PC300 synchronous communication boards.

diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index 2c5c35c..ba891dd 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -253,6 +253,7 @@ struct tty_operations {

struct tty_driver {
int magic; /* magic number for this structure */
+ struct kref kref; /* Reference management */
struct cdev cdev;
struct module *owner;
const char *driver_name;
@@ -266,7 +267,6 @@ struct tty_driver {
short subtype; /* subtype of tty driver */
struct ktermios init_termios; /* Initial termios */
int flags; /* tty driver flags */
- int refcount; /* for loadable tty drivers */
struct proc_dir_entry *proc_entry; /* /proc fs entry */
struct tty_driver *other; /* only used for the PTY driver */

@@ -288,12 +288,19 @@ struct tty_driver {

extern struct list_head tty_drivers;

-struct tty_driver *alloc_tty_driver(int lines);
-void put_tty_driver(struct tty_driver *driver);
-void tty_set_operations(struct tty_driver *driver,
+extern struct tty_driver *alloc_tty_driver(int lines);
+extern void put_tty_driver(struct tty_driver *driver);
+extern void tty_set_operations(struct tty_driver *driver,
const struct tty_operations *op);
extern struct tty_driver *tty_find_polling_driver(char *name, int *line);

+extern void tty_driver_kref_put(struct tty_driver *driver);
+extern inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
+{
+ kref_get(&d->kref);
+ return d;
+}
+
/* tty driver magic number */
#define TTY_DRIVER_MAGIC 0x5402