linux/drivers/video/backlight/lcd.c
Andrea Righi 513adb5868 fbdev: fix info->lock deadlock in fbcon_event_notify()
fb_notifier_call_chain() is called with info->lock held, i.e.  in
do_fb_ioctl() => FBIOPUT_VSCREENINFO => fb_set_var() and the some
notifier callbacks, like fbcon_event_notify(), try to re-acquire
info->lock again.

Remove the lock/unlock_fb_info() in all the framebuffer notifier
callbacks' and be sure to always call fb_notifier_call_chain() with
info->lock held.

Reported-by: Pavel Roskin <proski@gnu.org>
Reported-by: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-13 15:04:28 -07:00

279 lines
6.6 KiB
C

/*
* LCD Lowlevel Control Abstraction
*
* Copyright (C) 2003,2004 Hewlett-Packard Company
*
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/lcd.h>
#include <linux/notifier.h>
#include <linux/ctype.h>
#include <linux/err.h>
#include <linux/fb.h>
#if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
defined(CONFIG_LCD_CLASS_DEVICE_MODULE))
/* This callback gets called when something important happens inside a
* framebuffer driver. We're looking if that important event is blanking,
* and if it is, we're switching lcd power as well ...
*/
static int fb_notifier_callback(struct notifier_block *self,
unsigned long event, void *data)
{
struct lcd_device *ld;
struct fb_event *evdata = data;
/* If we aren't interested in this event, skip it immediately ... */
switch (event) {
case FB_EVENT_BLANK:
case FB_EVENT_MODE_CHANGE:
case FB_EVENT_MODE_CHANGE_ALL:
break;
default:
return 0;
}
ld = container_of(self, struct lcd_device, fb_notif);
if (!ld->ops)
return 0;
mutex_lock(&ld->ops_lock);
if (!ld->ops->check_fb || ld->ops->check_fb(ld, evdata->info)) {
if (event == FB_EVENT_BLANK) {
if (ld->ops->set_power)
ld->ops->set_power(ld, *(int *)evdata->data);
} else {
if (ld->ops->set_mode)
ld->ops->set_mode(ld, evdata->data);
}
}
mutex_unlock(&ld->ops_lock);
return 0;
}
static int lcd_register_fb(struct lcd_device *ld)
{
memset(&ld->fb_notif, 0, sizeof(&ld->fb_notif));
ld->fb_notif.notifier_call = fb_notifier_callback;
return fb_register_client(&ld->fb_notif);
}
static void lcd_unregister_fb(struct lcd_device *ld)
{
fb_unregister_client(&ld->fb_notif);
}
#else
static int lcd_register_fb(struct lcd_device *ld)
{
return 0;
}
static inline void lcd_unregister_fb(struct lcd_device *ld)
{
}
#endif /* CONFIG_FB */
static ssize_t lcd_show_power(struct device *dev, struct device_attribute *attr,
char *buf)
{
int rc;
struct lcd_device *ld = to_lcd_device(dev);
mutex_lock(&ld->ops_lock);
if (ld->ops && ld->ops->get_power)
rc = sprintf(buf, "%d\n", ld->ops->get_power(ld));
else
rc = -ENXIO;
mutex_unlock(&ld->ops_lock);
return rc;
}
static ssize_t lcd_store_power(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
int rc = -ENXIO;
char *endp;
struct lcd_device *ld = to_lcd_device(dev);
int power = simple_strtoul(buf, &endp, 0);
size_t size = endp - buf;
if (*endp && isspace(*endp))
size++;
if (size != count)
return -EINVAL;
mutex_lock(&ld->ops_lock);
if (ld->ops && ld->ops->set_power) {
pr_debug("lcd: set power to %d\n", power);
ld->ops->set_power(ld, power);
rc = count;
}
mutex_unlock(&ld->ops_lock);
return rc;
}
static ssize_t lcd_show_contrast(struct device *dev,
struct device_attribute *attr, char *buf)
{
int rc = -ENXIO;
struct lcd_device *ld = to_lcd_device(dev);
mutex_lock(&ld->ops_lock);
if (ld->ops && ld->ops->get_contrast)
rc = sprintf(buf, "%d\n", ld->ops->get_contrast(ld));
mutex_unlock(&ld->ops_lock);
return rc;
}
static ssize_t lcd_store_contrast(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
int rc = -ENXIO;
char *endp;
struct lcd_device *ld = to_lcd_device(dev);
int contrast = simple_strtoul(buf, &endp, 0);
size_t size = endp - buf;
if (*endp && isspace(*endp))
size++;
if (size != count)
return -EINVAL;
mutex_lock(&ld->ops_lock);
if (ld->ops && ld->ops->set_contrast) {
pr_debug("lcd: set contrast to %d\n", contrast);
ld->ops->set_contrast(ld, contrast);
rc = count;
}
mutex_unlock(&ld->ops_lock);
return rc;
}
static ssize_t lcd_show_max_contrast(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct lcd_device *ld = to_lcd_device(dev);
return sprintf(buf, "%d\n", ld->props.max_contrast);
}
static struct class *lcd_class;
static void lcd_device_release(struct device *dev)
{
struct lcd_device *ld = to_lcd_device(dev);
kfree(ld);
}
static struct device_attribute lcd_device_attributes[] = {
__ATTR(lcd_power, 0644, lcd_show_power, lcd_store_power),
__ATTR(contrast, 0644, lcd_show_contrast, lcd_store_contrast),
__ATTR(max_contrast, 0444, lcd_show_max_contrast, NULL),
__ATTR_NULL,
};
/**
* lcd_device_register - register a new object of lcd_device class.
* @name: the name of the new object(must be the same as the name of the
* respective framebuffer device).
* @devdata: an optional pointer to be stored in the device. The
* methods may retrieve it by using lcd_get_data(ld).
* @ops: the lcd operations structure.
*
* Creates and registers a new lcd device. Returns either an ERR_PTR()
* or a pointer to the newly allocated device.
*/
struct lcd_device *lcd_device_register(const char *name, struct device *parent,
void *devdata, struct lcd_ops *ops)
{
struct lcd_device *new_ld;
int rc;
pr_debug("lcd_device_register: name=%s\n", name);
new_ld = kzalloc(sizeof(struct lcd_device), GFP_KERNEL);
if (!new_ld)
return ERR_PTR(-ENOMEM);
mutex_init(&new_ld->ops_lock);
mutex_init(&new_ld->update_lock);
new_ld->dev.class = lcd_class;
new_ld->dev.parent = parent;
new_ld->dev.release = lcd_device_release;
dev_set_name(&new_ld->dev, name);
dev_set_drvdata(&new_ld->dev, devdata);
rc = device_register(&new_ld->dev);
if (rc) {
kfree(new_ld);
return ERR_PTR(rc);
}
rc = lcd_register_fb(new_ld);
if (rc) {
device_unregister(&new_ld->dev);
return ERR_PTR(rc);
}
new_ld->ops = ops;
return new_ld;
}
EXPORT_SYMBOL(lcd_device_register);
/**
* lcd_device_unregister - unregisters a object of lcd_device class.
* @ld: the lcd device object to be unregistered and freed.
*
* Unregisters a previously registered via lcd_device_register object.
*/
void lcd_device_unregister(struct lcd_device *ld)
{
if (!ld)
return;
mutex_lock(&ld->ops_lock);
ld->ops = NULL;
mutex_unlock(&ld->ops_lock);
lcd_unregister_fb(ld);
device_unregister(&ld->dev);
}
EXPORT_SYMBOL(lcd_device_unregister);
static void __exit lcd_class_exit(void)
{
class_destroy(lcd_class);
}
static int __init lcd_class_init(void)
{
lcd_class = class_create(THIS_MODULE, "lcd");
if (IS_ERR(lcd_class)) {
printk(KERN_WARNING "Unable to create backlight class; errno = %ld\n",
PTR_ERR(lcd_class));
return PTR_ERR(lcd_class);
}
lcd_class->dev_attrs = lcd_device_attributes;
return 0;
}
/*
* if this is compiled into the kernel, we need to ensure that the
* class is registered before users of the class try to register lcd's
*/
postcore_initcall(lcd_class_init);
module_exit(lcd_class_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
MODULE_DESCRIPTION("LCD Lowlevel Control Abstraction");