Attachment 92135 Details for Bug 70523 – fix tty unregistering lockdep

[patch] fix tty unregistering lockdep

0001-tty-vt-fix-lock-dependency-during-console-unregister.patch (text/plain), 4.87 KB, created by Imre Deak on 2014-01-15 11:43:54 UTC

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Creator: Imre Deak

Created: 2014-01-15 11:43:54 UTC

Size: 4.87 KB

patch

obsolete

>From de4c13f0938fb46c21b55b328bd22132207f860b Mon Sep 17 00:00:00 2001
>From: Imre Deak <imre.deak@intel.com>
>Date: Tue, 14 Jan 2014 19:01:44 +0200
>Subject: [PATCH 1/2] tty/vt: fix lock dependency during console unregistering
>
>Signed-off-by: Imre Deak <imre.deak@intel.com>
>---
> drivers/tty/vt/vt.c           | 52 ++++++++++++++++++++++++++++++-------------
> drivers/video/console/fbcon.c |  1 +
> drivers/video/fbmem.c         |  2 ++
> include/linux/console.h       |  1 +
> 4 files changed, 40 insertions(+), 16 deletions(-)
>
>diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
>index 61b1137..44e9f9e 100644
>--- a/drivers/tty/vt/vt.c
>+++ b/drivers/tty/vt/vt.c
>@@ -108,6 +108,7 @@
> #define CON_DRIVER_FLAG_MODULE 1
> #define CON_DRIVER_FLAG_INIT   2
> #define CON_DRIVER_FLAG_ATTR   4
>+#define CON_DRIVER_FLAG_ZOMBIE 8
> 
> struct con_driver {
> 	const struct consw *con;
>@@ -3234,11 +3235,8 @@ static int vt_bind(struct con_driver *con)
> 		if (first == 0 && last == MAX_NR_CONSOLES -1)
> 			deflt = 1;
> 
>-		if (first != -1) {
>-			console_lock();
>+		if (first != -1)
> 			do_bind_con_driver(csw, first, last, deflt);
>-			console_unlock();
>-		}
> 
> 		first = -1;
> 		last = -1;
>@@ -3276,11 +3274,8 @@ static int vt_unbind(struct con_driver *con)
> 		if (first == 0 && last == MAX_NR_CONSOLES -1)
> 			deflt = 1;
> 
>-		if (first != -1) {
>-			console_lock();
>+		if (first != -1)
> 			do_unbind_con_driver(csw, first, last, deflt);
>-			console_unlock();
>-		}
> 
> 		first = -1;
> 		last = -1;
>@@ -3307,11 +3302,15 @@ static ssize_t store_bind(struct device *dev, struct device_attribute *attr,
> 	struct con_driver *con = dev_get_drvdata(dev);
> 	int bind = simple_strtoul(buf, NULL, 0);
> 
>+	console_lock();
>+
> 	if (bind)
> 		vt_bind(con);
> 	else
> 		vt_unbind(con);
> 
>+	console_unlock();
>+
> 	return count;
> }
> 
>@@ -3517,7 +3516,8 @@ static int do_register_con_driver(const struct consw *csw, int first, int last)
> 	for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
> 		con_driver = &registered_con_driver[i];
> 
>-		if (con_driver->con == NULL) {
>+		if (con_driver->con == NULL &&
>+		    !(con_driver->flag & CON_DRIVER_FLAG_ZOMBIE)) {
> 			con_driver->con = csw;
> 			con_driver->desc = desc;
> 			con_driver->node = i;
>@@ -3577,24 +3577,43 @@ int do_unregister_con_driver(const struct consw *csw)
> 
> 		if (con_driver->con == csw &&
> 		    con_driver->flag & CON_DRIVER_FLAG_MODULE) {
>+			con_driver->con = NULL;
>+			con_driver->flag = CON_DRIVER_FLAG_ZOMBIE;
>+			retval = 0;
>+			break;
>+		}
>+	}
>+err:
>+	return retval;
>+}
>+EXPORT_SYMBOL_GPL(do_unregister_con_driver);
>+
>+void prune_zombie_con_drivers(void)
>+{
>+	int i;
>+
>+	console_lock();
>+	for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
>+		struct con_driver *con_driver = &registered_con_driver[i];
>+
>+		if (con_driver->flag & CON_DRIVER_FLAG_ZOMBIE) {
>+			console_unlock();
> 			vtconsole_deinit_device(con_driver);
> 			device_destroy(vtconsole_class,
> 				       MKDEV(0, con_driver->node));
>-			con_driver->con = NULL;
>+			console_lock();
> 			con_driver->desc = NULL;
>+			con_driver->flag &= ~CON_DRIVER_FLAG_ZOMBIE;
>+			WARN_ON(con_driver->flag);
> 			con_driver->dev = NULL;
> 			con_driver->node = 0;
>-			con_driver->flag = 0;
> 			con_driver->first = 0;
> 			con_driver->last = 0;
>-			retval = 0;
>-			break;
> 		}
> 	}
>-err:
>-	return retval;
>+	console_unlock();
> }
>-EXPORT_SYMBOL_GPL(do_unregister_con_driver);
>+EXPORT_SYMBOL_GPL(prune_zombie_con_drivers);
> 
> /*
>  *	If we support more console drivers, this function is used
>@@ -3632,6 +3651,7 @@ void give_up_console(const struct consw *csw)
> 	console_lock();
> 	do_unregister_con_driver(csw);
> 	console_unlock();
>+	prune_zombie_con_drivers();
> }
> 
> static int __init vtconsole_class_init(void)
>diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
>index cd8a802..26d180c 100644
>--- a/drivers/video/console/fbcon.c
>+++ b/drivers/video/console/fbcon.c
>@@ -3623,6 +3623,7 @@ static void __exit fb_console_exit(void)
> 	fbcon_exit();
> 	do_unregister_con_driver(&fb_con);
> 	console_unlock();
>+	prune_zombie_con_drivers();
> }	
> 
> module_exit(fb_console_exit);
>diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
>index e296967..1a7cf9e 100644
>--- a/drivers/video/fbmem.c
>+++ b/drivers/video/fbmem.c
>@@ -1725,6 +1725,8 @@ static int do_unregister_framebuffer(struct fb_info *fb_info)
> 	fb_notifier_call_chain(FB_EVENT_FB_UNREGISTERED, &event);
> 	console_unlock();
> 
>+	prune_zombie_con_drivers();
>+
> 	/* this may free fb info */
> 	put_fb_info(fb_info);
> 	return 0;
>diff --git a/include/linux/console.h b/include/linux/console.h
>index 7571a16..b7bf097 100644
>--- a/include/linux/console.h
>+++ b/include/linux/console.h
>@@ -76,6 +76,7 @@ extern const struct consw prom_con;	/* SPARC PROM console */
> 
> int con_is_bound(const struct consw *csw);
> int do_unregister_con_driver(const struct consw *csw);
>+void prune_zombie_con_drivers(void);
> int do_take_over_console(const struct consw *sw, int first, int last, int deflt);
> void give_up_console(const struct consw *sw);
> #ifdef CONFIG_HW_CONSOLE
>-- 
>1.8.4
>

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Attachments on bug 70523: 87716 | 92135 | 92136 | 107602

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