tty: kref the tty driver object

Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tty: kref the tty driver object
Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Alan Cox · Linus Torvalds
1 parent 99f1fe189d
Showing 5 changed files with 80 additions and 58 deletions Side-by-side Diff
drivers/char/ip2/ip2main.c
drivers/char/pty.c
drivers/char/tty_io.c
drivers/net/wan/Kconfig
include/linux/tty_driver.h
@@ -264,8 +264,8 @@
 /**********/
  
 #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 @@
 	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;
@@ -571,8 +571,11 @@
 	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);
@@ -276,7 +276,7 @@
 		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 @@
  
 		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 @@
 			*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 @@
 	/* 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 @@
 	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 @@
 			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 @@
 #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 @@
 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 @@
 		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 @@
  
 	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 @@
 	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 @@
  
 	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 @@
 	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 @@
 		    tty_register_device(driver, i, NULL);
 	}
 	proc_tty_register_driver(driver);
+	driver->flags |= TTY_DRIVER_INSTALLED;
 	return 0;
 }
  
  
  
  
@@ -3034,46 +3073,19 @@
  */
 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)
@@ -205,7 +205,7 @@
  
 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.
  
@@ -253,6 +253,7 @@
  
 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 @@
 	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 */
  
  
@@ -288,11 +288,18 @@
  
 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
...	...	@@ -264,8 +264,8 @@
264	264	/**********/
265	265
266	266	#if defined(MODULE) && defined(IP2DEBUG_OPEN)
267		-#define DBG_CNT(s) printk(KERN_DEBUG "(%s): [%x] refc=%d, ttyc=%d, modc=%x -> %s\n", \
268		- tty->name,(pCh->flags),ip2_tty_driver->refcount, \
	267	+#define DBG_CNT(s) printk(KERN_DEBUG "(%s): [%x] ttyc=%d, modc=%x -> %s\n", \
	268	+ tty->name,(pCh->flags), \
269	269	tty->count,/GET_USE_COUNT(module)/0,s)
270	270	#else
271	271	#define DBG_CNT(s)
...	...	@@ -2893,7 +2893,7 @@
2893	2893	case 13:
2894	2894	switch ( cmd ) {
2895	2895	case 64: /* Driver - ip2stat */
2896		- rc = put_user(ip2_tty_driver->refcount, pIndex++ );
	2896	+ rc = put_user(-1, pIndex++ );
2897	2897	rc = put_user(irq_counter, pIndex++ );
2898	2898	rc = put_user(bh_counter, pIndex++ );
2899	2899	break;
...	...	@@ -571,8 +571,11 @@
571	571	if (tty_register_driver(pts_driver))
572	572	panic("Couldn't register Unix98 pts driver");
573	573
	574	+ /* FIXME: WTF */
	575	+#if 0
574	576	pty_table[1].data = &ptm_driver->refcount;
575		- register_sysctl_table(pty_root_table);
	577	+#endif
	578	+ register_sysctl_table(pty_root_table);
576	579
577	580	/* Now create the /dev/ptmx special device */
578	581	tty_default_fops(&ptmx_fops);
...	...	@@ -276,7 +276,7 @@
276	276	if (device < base \|\| device >= base + p->num)
277	277	continue;
278	278	*index = device - base;
279		- return p;
	279	+ return tty_driver_kref_get(p);
280	280	}
281	281	return NULL;
282	282	}
...	...	@@ -320,7 +320,7 @@
320	320
321	321	if (tty_line >= 0 && tty_line <= p->num && p->ops &&
322	322	p->ops->poll_init && !p->ops->poll_init(p, tty_line, str)) {
323		- res = p;
	323	+ res = tty_driver_kref_get(p);
324	324	*line = tty_line;
325	325	break;
326	326	}
...	...	@@ -1410,7 +1410,7 @@
1410	1410	*o_ltp_loc = o_ltp;
1411	1411	o_tty->termios = *o_tp_loc;
1412	1412	o_tty->termios_locked = *o_ltp_loc;
1413		- driver->other->refcount++;
	1413	+ tty_driver_kref_get(driver->other);
1414	1414	if (driver->subtype == PTY_TYPE_MASTER)
1415	1415	o_tty->count++;
1416	1416
...	...	@@ -1438,7 +1438,7 @@
1438	1438	/* Compatibility until drivers always set this */
1439	1439	tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
1440	1440	tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
1441		- driver->refcount++;
	1441	+ tty_driver_kref_get(driver);
1442	1442	tty->count++;
1443	1443
1444	1444	/*
...	...	@@ -1530,8 +1530,7 @@
1530	1530	else
1531	1531	tty_shutdown(tty);
1532	1532	tty->magic = 0;
1533		- /* FIXME: locking on tty->driver->refcount */
1534		- tty->driver->refcount--;
	1533	+ tty_driver_kref_put(driver);
1535	1534	module_put(driver->owner);
1536	1535
1537	1536	file_list_lock();
...	...	@@ -1854,7 +1853,7 @@
1854	1853	mutex_unlock(&tty_mutex);
1855	1854	return -ENXIO;
1856	1855	}
1857		- driver = tty->driver;
	1856	+ driver = tty_driver_kref_get(tty->driver);
1858	1857	index = tty->index;
1859	1858	filp->f_flags \|= O_NONBLOCK; /* Don't let /dev/tty block */
1860	1859	/* noctty = 1; */
1861	1860
...	...	@@ -1865,14 +1864,14 @@
1865	1864	#ifdef CONFIG_VT
1866	1865	if (device == MKDEV(TTY_MAJOR, 0)) {
1867	1866	extern struct tty_driver *console_driver;
1868		- driver = console_driver;
	1867	+ driver = tty_driver_kref_get(console_driver);
1869	1868	index = fg_console;
1870	1869	noctty = 1;
1871	1870	goto got_driver;
1872	1871	}
1873	1872	#endif
1874	1873	if (device == MKDEV(TTYAUX_MAJOR, 1)) {
1875		- driver = console_device(&index);
	1874	+ driver = tty_driver_kref_get(console_device(&index));
1876	1875	if (driver) {
1877	1876	/* Don't let /dev/console block */
1878	1877	filp->f_flags \|= O_NONBLOCK;
...	...	@@ -1891,6 +1890,7 @@
1891	1890	got_driver:
1892	1891	retval = tty_init_dev(driver, index, &tty, 0);
1893	1892	mutex_unlock(&tty_mutex);
	1893	+ tty_driver_kref_put(driver);
1894	1894	if (retval)
1895	1895	return retval;
1896	1896
...	...	@@ -2866,7 +2866,6 @@
2866	2866	return tty->ops->put_char(tty, ch);
2867	2867	return tty->ops->write(tty, &ch, 1);
2868	2868	}
2869		-
2870	2869	EXPORT_SYMBOL_GPL(tty_put_char);
2871	2870
2872	2871	struct class *tty_class;
...	...	@@ -2909,6 +2908,7 @@
2909	2908
2910	2909	return device_create_drvdata(tty_class, device, dev, NULL, name);
2911	2910	}
	2911	+EXPORT_SYMBOL(tty_register_device);
2912	2912
2913	2913	/**
2914	2914	* tty_unregister_device - unregister a tty device
...	...	@@ -2926,8 +2926,6 @@
2926	2926	device_destroy(tty_class,
2927	2927	MKDEV(driver->major, driver->minor_start) + index);
2928	2928	}
2929		-
2930		-EXPORT_SYMBOL(tty_register_device);
2931	2929	EXPORT_SYMBOL(tty_unregister_device);
2932	2930
2933	2931	struct tty_driver *alloc_tty_driver(int lines)
2934	2932
2935	2933
2936	2934
2937	2935
2938	2936
2939	2937
2940	2938
...	...	@@ -2936,27 +2934,70 @@
2936	2934
2937	2935	driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
2938	2936	if (driver) {
	2937	+ kref_init(&driver->kref);
2939	2938	driver->magic = TTY_DRIVER_MAGIC;
2940	2939	driver->num = lines;
2941	2940	/* later we'll move allocation of tables here */
2942	2941	}
2943	2942	return driver;
2944	2943	}
	2944	+EXPORT_SYMBOL(alloc_tty_driver);
2945	2945
2946		-void put_tty_driver(struct tty_driver *driver)
	2946	+static void destruct_tty_driver(struct kref *kref)
2947	2947	{
	2948	+ struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
	2949	+ int i;
	2950	+ struct ktermios *tp;
	2951	+ void *p;
	2952	+
	2953	+ if (driver->flags & TTY_DRIVER_INSTALLED) {
	2954	+ /*
	2955	+ * Free the termios and termios_locked structures because
	2956	+ * we don't want to get memory leaks when modular tty
	2957	+ * drivers are removed from the kernel.
	2958	+ */
	2959	+ for (i = 0; i < driver->num; i++) {
	2960	+ tp = driver->termios[i];
	2961	+ if (tp) {
	2962	+ driver->termios[i] = NULL;
	2963	+ kfree(tp);
	2964	+ }
	2965	+ tp = driver->termios_locked[i];
	2966	+ if (tp) {
	2967	+ driver->termios_locked[i] = NULL;
	2968	+ kfree(tp);
	2969	+ }
	2970	+ if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
	2971	+ tty_unregister_device(driver, i);
	2972	+ }
	2973	+ p = driver->ttys;
	2974	+ proc_tty_unregister_driver(driver);
	2975	+ driver->ttys = NULL;
	2976	+ driver->termios = driver->termios_locked = NULL;
	2977	+ kfree(p);
	2978	+ cdev_del(&driver->cdev);
	2979	+ }
2948	2980	kfree(driver);
2949	2981	}
2950	2982
	2983	+void tty_driver_kref_put(struct tty_driver *driver)
	2984	+{
	2985	+ kref_put(&driver->kref, destruct_tty_driver);
	2986	+}
	2987	+EXPORT_SYMBOL(tty_driver_kref_put);
	2988	+
2951	2989	void tty_set_operations(struct tty_driver *driver,
2952	2990	const struct tty_operations *op)
2953	2991	{
2954	2992	driver->ops = op;
2955	2993	};
	2994	+EXPORT_SYMBOL(tty_set_operations);
2956	2995
2957		-EXPORT_SYMBOL(alloc_tty_driver);
	2996	+void put_tty_driver(struct tty_driver *d)
	2997	+{
	2998	+ tty_driver_kref_put(d);
	2999	+}
2958	3000	EXPORT_SYMBOL(put_tty_driver);
2959		-EXPORT_SYMBOL(tty_set_operations);
2960	3001
2961	3002	/*
2962	3003	* Called by a tty driver to register itself.
...	...	@@ -2968,9 +3009,6 @@
2968	3009	dev_t dev;
2969	3010	void **p = NULL;
2970	3011
2971		- if (driver->flags & TTY_DRIVER_INSTALLED)
2972		- return 0;
2973		-
2974	3012	if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
2975	3013	p = kzalloc(driver->num * 3 * sizeof(void *), GFP_KERNEL);
2976	3014	if (!p)
...	...	@@ -3024,6 +3062,7 @@
3024	3062	tty_register_device(driver, i, NULL);
3025	3063	}
3026	3064	proc_tty_register_driver(driver);
	3065	+ driver->flags \|= TTY_DRIVER_INSTALLED;
3027	3066	return 0;
3028	3067	}
3029	3068
3030	3069
3031	3070
3032	3071
...	...	@@ -3034,46 +3073,19 @@
3034	3073	*/
3035	3074	int tty_unregister_driver(struct tty_driver *driver)
3036	3075	{
3037		- int i;
3038		- struct ktermios *tp;
3039		- void *p;
3040		-
	3076	+#if 0
	3077	+ /* FIXME */
3041	3078	if (driver->refcount)
3042	3079	return -EBUSY;
3043		-
	3080	+#endif
3044	3081	unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3045	3082	driver->num);
3046	3083	mutex_lock(&tty_mutex);
3047	3084	list_del(&driver->tty_drivers);
3048	3085	mutex_unlock(&tty_mutex);
3049		-
3050		- /*
3051		- * Free the termios and termios_locked structures because
3052		- * we don't want to get memory leaks when modular tty
3053		- * drivers are removed from the kernel.
3054		- */
3055		- for (i = 0; i < driver->num; i++) {
3056		- tp = driver->termios[i];
3057		- if (tp) {
3058		- driver->termios[i] = NULL;
3059		- kfree(tp);
3060		- }
3061		- tp = driver->termios_locked[i];
3062		- if (tp) {
3063		- driver->termios_locked[i] = NULL;
3064		- kfree(tp);
3065		- }
3066		- if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3067		- tty_unregister_device(driver, i);
3068		- }
3069		- p = driver->ttys;
3070		- proc_tty_unregister_driver(driver);
3071		- driver->ttys = NULL;
3072		- driver->termios = driver->termios_locked = NULL;
3073		- kfree(p);
3074		- cdev_del(&driver->cdev);
3075	3086	return 0;
3076	3087	}
	3088	+
3077	3089	EXPORT_SYMBOL(tty_unregister_driver);
3078	3090
3079	3091	dev_t tty_devnum(struct tty_struct *tty)
...	...	@@ -205,7 +205,7 @@
205	205
206	206	config PC300
207	207	tristate "Cyclades-PC300 support (RS-232/V.35, X.21, T1/E1 boards)"
208		- depends on HDLC && PCI
	208	+ depends on HDLC && PCI && BROKEN
209	209	---help---
210	210	Driver for the Cyclades-PC300 synchronous communication boards.
211	211
...	...	@@ -253,6 +253,7 @@
253	253
254	254	struct tty_driver {
255	255	int magic; /* magic number for this structure */
	256	+ struct kref kref; /* Reference management */
256	257	struct cdev cdev;
257	258	struct module *owner;
258	259	const char *driver_name;
...	...	@@ -266,7 +267,6 @@
266	267	short subtype; /* subtype of tty driver */
267	268	struct ktermios init_termios; /* Initial termios */
268	269	int flags; /* tty driver flags */
269		- int refcount; /* for loadable tty drivers */
270	270	struct proc_dir_entry proc_entry; / /proc fs entry */
271	271	struct tty_driver other; / only used for the PTY driver */
272	272
273	273
...	...	@@ -288,11 +288,18 @@
288	288
289	289	extern struct list_head tty_drivers;
290	290
291		-struct tty_driver *alloc_tty_driver(int lines);
292		-void put_tty_driver(struct tty_driver *driver);
293		-void tty_set_operations(struct tty_driver *driver,
	291	+extern struct tty_driver *alloc_tty_driver(int lines);
	292	+extern void put_tty_driver(struct tty_driver *driver);
	293	+extern void tty_set_operations(struct tty_driver *driver,
294	294	const struct tty_operations *op);
295	295	extern struct tty_driver tty_find_polling_driver(char name, int *line);
	296	+
	297	+extern void tty_driver_kref_put(struct tty_driver *driver);
	298	+extern inline struct tty_driver tty_driver_kref_get(struct tty_driver d)
	299	+{
	300	+ kref_get(&d->kref);
	301	+ return d;
	302	+}
296	303
297	304	/* tty driver magic number */
298	305	#define TTY_DRIVER_MAGIC 0x5402