Commit 68eeb087 authored by Hans de Goede's avatar Hans de Goede Committed by Helge Deller
Browse files

fbdev: Use device_create_with_groups() to fix sysfs groups registration race 



The fbdev sysfs attributes are registered after sending the uevent for
the device creation, leaving a race window where e.g. udev rules may
not be able to access the sysfs attributes because the registration is
not done yet.

Fix this by switching to device_create_with_groups(). This also results in
a nice cleanup. After switching to device_create_with_groups() all that
is left of fb_init_device() is setting the drvdata and that can be passed
to device_create[_with_groups]() too. After which fb_init_device() can
be completely removed.

Dropping fb_init_device() + fb_cleanup_device() in turn allows removing
fb_info.class_flag as they were the only user of this field.

Fixes: 5fc830d6 ("fbdev: Register sysfs groups through device_add_group")
Cc: stable@vger.kernel.org
Cc: Shixiong Ou <oushixiong@kylinos.cn>
Signed-off-by: default avatarHans de Goede <johannes.goede@oss.qualcomm.com>
Signed-off-by: default avatarHelge Deller <deller@gmx.de>
parent 120adae7

drivers/video/fbdev/core/fbsysfs.c

+3 −33
Original line number Diff line number Diff line
@@ -12,8 +12,6 @@ 


#include "fb_internal.h"



#define FB_SYSFS_FLAG_ATTR 1



static int activate(struct fb_info *fb_info, struct fb_var_screeninfo *var)

{

	int err;
@@ -451,33 +449,7 @@ static struct attribute *fb_device_attrs[] = { 
	NULL,

};



static const struct attribute_group fb_device_attr_group = {

	.attrs          = fb_device_attrs,

};



static int fb_init_device(struct fb_info *fb_info)

{

	int ret;



	dev_set_drvdata(fb_info->dev, fb_info);



	fb_info->class_flag |= FB_SYSFS_FLAG_ATTR;



	ret = device_add_group(fb_info->dev, &fb_device_attr_group);

	if (ret)

		fb_info->class_flag &= ~FB_SYSFS_FLAG_ATTR;



	return 0;

}



static void fb_cleanup_device(struct fb_info *fb_info)

{

	if (fb_info->class_flag & FB_SYSFS_FLAG_ATTR) {

		device_remove_group(fb_info->dev, &fb_device_attr_group);



		fb_info->class_flag &= ~FB_SYSFS_FLAG_ATTR;

	}

}

ATTRIBUTE_GROUPS(fb_device);



int fb_device_create(struct fb_info *fb_info)

{
@@ -485,14 +457,13 @@ int fb_device_create(struct fb_info *fb_info) 
	dev_t devt = MKDEV(FB_MAJOR, node);

	int ret;



	fb_info->dev = device_create(fb_class, fb_info->device, devt, NULL, "fb%d", node);

	fb_info->dev = device_create_with_groups(fb_class, fb_info->device, devt, fb_info,

						 fb_device_groups, "fb%d", node);

	if (IS_ERR(fb_info->dev)) {

		/* Not fatal */

		ret = PTR_ERR(fb_info->dev);

		pr_warn("Unable to create device for framebuffer %d; error %d\n", node, ret);

		fb_info->dev = NULL;

	} else {

		fb_init_device(fb_info);

	}



	return 0;
@@ -505,7 +476,6 @@ void fb_device_destroy(struct fb_info *fb_info) 
	if (!fb_info->dev)

		return;



	fb_cleanup_device(fb_info);

	device_destroy(fb_class, devt);

	fb_info->dev = NULL;

}

include/linux/fb.h

+0 −1
Original line number Diff line number Diff line
@@ -493,7 +493,6 @@ struct fb_info { 
#if defined(CONFIG_FB_DEVICE)

	struct device *dev;		/* This is this fb device */

#endif

	int class_flag;                    /* private sysfs flags */

#ifdef CONFIG_FB_TILEBLITTING

	struct fb_tile_ops *tileops;    /* Tile Blitting */

#endif