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staging: android: timed_output: fix sysfs file creation race 

The sysfs file for the driver was being created _after_ the device was
announced to userspace, causing a race with any tools looking for sysfs
files.

Fix the race by using the default attribute group for the class.

Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Greg Kroah-Hartman 2013-08-24 10:27:29 -07:00
parent 76e1f486b2
commit 9d3ab80174
1 changed files with 10 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
drivers/staging/android/timed_output.c
View File

@ -28,7 +28,7 @@ static struct class *timed_output_class;
static atomic_t device_count;
static ssize_t enable_show(struct device *dev, struct device_attribute *attr,
char *buf)
char *buf)
{
struct timed_output_dev *tdev = dev_get_drvdata(dev);
int remaining = tdev->get_time(tdev);
@ -36,9 +36,8 @@ static ssize_t enable_show(struct device *dev, struct device_attribute *attr,
return sprintf(buf, "%d\n", remaining);
}
static ssize_t enable_store(
struct device *dev, struct device_attribute *attr,
const char *buf, size_t size)
static ssize_t enable_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t size)
{
struct timed_output_dev *tdev = dev_get_drvdata(dev);
int value;
@ -50,8 +49,13 @@ static ssize_t enable_store(
return size;
}
static DEVICE_ATTR_RW(enable);
static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, enable_show, enable_store);
static struct attribute *timed_output_attrs[] = {
&dev_attr_enable.attr,
NULL,
};
ATTRIBUTE_GROUPS(timed_output);
static int create_timed_output_class(void)
{
@ -60,6 +64,7 @@ static int create_timed_output_class(void)
if (IS_ERR(timed_output_class))
return PTR_ERR(timed_output_class);
atomic_set(&device_count, 0);
timed_output_class->dev_groups = timed_output_groups;
}
return 0;
@ -82,27 +87,15 @@ int timed_output_dev_register(struct timed_output_dev *tdev)
if (IS_ERR(tdev->dev))
return PTR_ERR(tdev->dev);
ret = device_create_file(tdev->dev, &dev_attr_enable);
if (ret < 0)
goto err_create_file;
dev_set_drvdata(tdev->dev, tdev);
tdev->state = 0;
return 0;
err_create_file:
device_destroy(timed_output_class, MKDEV(0, tdev->index));
pr_err("failed to register driver %s\n",
tdev->name);
return ret;
}
EXPORT_SYMBOL_GPL(timed_output_dev_register);
void timed_output_dev_unregister(struct timed_output_dev *tdev)
{
tdev->enable(tdev, 0);
device_remove_file(tdev->dev, &dev_attr_enable);
device_destroy(timed_output_class, MKDEV(0, tdev->index));
dev_set_drvdata(tdev->dev, NULL);
}