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leds: Fix led trigger locking bugs

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Convert part of the led trigger core from rw spinlocks to rw
semaphores. We're calling functions which can sleep from invalid
contexts otherwise. Fixes bug #9264.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
This commit is contained in:
Richard Purdie 2007-11-10 13:29:04 +00:00
parent f194d132e4
commit dc47206e55
3 changed files with 30 additions and 28 deletions
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6
drivers/leds/led-class.c
View file

@ -111,7 +111,7 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
write_unlock(&leds_list_lock);
#ifdef CONFIG_LEDS_TRIGGERS
rwlock_init(&led_cdev->trigger_lock);
init_rwsem(&led_cdev->trigger_lock);
rc = device_create_file(led_cdev->dev, &dev_attr_trigger);
if (rc)
@ -147,10 +147,10 @@ void led_classdev_unregister(struct led_classdev *led_cdev)
device_remove_file(led_cdev->dev, &dev_attr_brightness);
#ifdef CONFIG_LEDS_TRIGGERS
device_remove_file(led_cdev->dev, &dev_attr_trigger);
write_lock(&led_cdev->trigger_lock);
down_write(&led_cdev->trigger_lock);
if (led_cdev->trigger)
led_trigger_set(led_cdev, NULL);
write_unlock(&led_cdev->trigger_lock);
up_write(&led_cdev->trigger_lock);
#endif
device_unregister(led_cdev->dev);

49
drivers/leds/led-triggers.c
View file

@ -19,13 +19,14 @@
#include <linux/device.h>
#include <linux/sysdev.h>
#include <linux/timer.h>
#include <linux/rwsem.h>
#include <linux/leds.h>
#include "leds.h"
/*
* Nests outside led_cdev->trigger_lock
*/
static DEFINE_RWLOCK(triggers_list_lock);
static DECLARE_RWSEM(triggers_list_lock);
static LIST_HEAD(trigger_list);
ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
@ -44,24 +45,24 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
trigger_name[len - 1] = '\0';
if (!strcmp(trigger_name, "none")) {
write_lock(&led_cdev->trigger_lock);
down_write(&led_cdev->trigger_lock);
led_trigger_set(led_cdev, NULL);
write_unlock(&led_cdev->trigger_lock);
up_write(&led_cdev->trigger_lock);
return count;
}
read_lock(&triggers_list_lock);
down_read(&triggers_list_lock);
list_for_each_entry(trig, &trigger_list, next_trig) {
if (!strcmp(trigger_name, trig->name)) {
write_lock(&led_cdev->trigger_lock);
down_write(&led_cdev->trigger_lock);
led_trigger_set(led_cdev, trig);
write_unlock(&led_cdev->trigger_lock);
up_write(&led_cdev->trigger_lock);
read_unlock(&triggers_list_lock);
up_read(&triggers_list_lock);
return count;
}
}
read_unlock(&triggers_list_lock);
up_read(&triggers_list_lock);
return -EINVAL;
}
@ -74,8 +75,8 @@ ssize_t led_trigger_show(struct device *dev, struct device_attribute *attr,
struct led_trigger *trig;
int len = 0;
read_lock(&triggers_list_lock);
read_lock(&led_cdev->trigger_lock);
down_read(&triggers_list_lock);
down_read(&led_cdev->trigger_lock);
if (!led_cdev->trigger)
len += sprintf(buf+len, "[none] ");
@ -89,8 +90,8 @@ ssize_t led_trigger_show(struct device *dev, struct device_attribute *attr,
else
len += sprintf(buf+len, "%s ", trig->name);
}
read_unlock(&led_cdev->trigger_lock);
read_unlock(&triggers_list_lock);
up_read(&led_cdev->trigger_lock);
up_read(&triggers_list_lock);
len += sprintf(len+buf, "\n");
return len;
@ -145,14 +146,14 @@ void led_trigger_set_default(struct led_classdev *led_cdev)
if (!led_cdev->default_trigger)
return;
read_lock(&triggers_list_lock);
write_lock(&led_cdev->trigger_lock);
down_read(&triggers_list_lock);
down_write(&led_cdev->trigger_lock);
list_for_each_entry(trig, &trigger_list, next_trig) {
if (!strcmp(led_cdev->default_trigger, trig->name))
led_trigger_set(led_cdev, trig);
}
write_unlock(&led_cdev->trigger_lock);
read_unlock(&triggers_list_lock);
up_write(&led_cdev->trigger_lock);
up_read(&triggers_list_lock);
}
int led_trigger_register(struct led_trigger *trigger)
@ -163,18 +164,18 @@ int led_trigger_register(struct led_trigger *trigger)
INIT_LIST_HEAD(&trigger->led_cdevs);
/* Add to the list of led triggers */
write_lock(&triggers_list_lock);
down_write(&triggers_list_lock);
list_add_tail(&trigger->next_trig, &trigger_list);
write_unlock(&triggers_list_lock);
up_write(&triggers_list_lock);
/* Register with any LEDs that have this as a default trigger */
read_lock(&leds_list_lock);
list_for_each_entry(led_cdev, &leds_list, node) {
write_lock(&led_cdev->trigger_lock);
down_write(&led_cdev->trigger_lock);
if (!led_cdev->trigger && led_cdev->default_trigger &&
!strcmp(led_cdev->default_trigger, trigger->name))
led_trigger_set(led_cdev, trigger);
write_unlock(&led_cdev->trigger_lock);
up_write(&led_cdev->trigger_lock);
}
read_unlock(&leds_list_lock);
@ -206,17 +207,17 @@ void led_trigger_unregister(struct led_trigger *trigger)
struct led_classdev *led_cdev;
/* Remove from the list of led triggers */
write_lock(&triggers_list_lock);
down_write(&triggers_list_lock);
list_del(&trigger->next_trig);
write_unlock(&triggers_list_lock);
up_write(&triggers_list_lock);
/* Remove anyone actively using this trigger */
read_lock(&leds_list_lock);
list_for_each_entry(led_cdev, &leds_list, node) {
write_lock(&led_cdev->trigger_lock);
down_write(&led_cdev->trigger_lock);
if (led_cdev->trigger == trigger)
led_trigger_set(led_cdev, NULL);
write_unlock(&led_cdev->trigger_lock);
up_write(&led_cdev->trigger_lock);
}
read_unlock(&leds_list_lock);
}

3
include/linux/leds.h
View file

@ -14,6 +14,7 @@
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/rwsem.h>
struct device;
/*
@ -43,7 +44,7 @@ struct led_classdev {
#ifdef CONFIG_LEDS_TRIGGERS
/* Protects the trigger data below */
rwlock_t trigger_lock;
struct rw_semaphore trigger_lock;
struct led_trigger *trigger;
struct list_head trig_list;