Commit 47eba33a authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman
Browse files

w1: remove race with sysfs file creation 



W1 slave sysfs files are created _after_ userspace is notified that the
device has been added to the system.  Fix that race by moving the
creation/remove of the files to the bus notifier that is there for doing
this type of thing.

Acked-by: default avatarEvgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 3e1026b3

drivers/w1/w1.c

+73 −38
Original line number Diff line number Diff line
@@ -587,6 +587,73 @@ end: 
	return err;

}



/*

 * Handle sysfs file creation and removal here, before userspace is told that

 * the device is added / removed from the system

 */

static int w1_bus_notify(struct notifier_block *nb, unsigned long action,

			 void *data)

{

	struct device *dev = data;

	struct w1_slave *sl;

	int err;



	/*

	 * Only care about slave devices at the moment.  Yes, we should use a

	 * separate "type" for this, but for now, look at the release function

	 * to know which type it is...

	 */

	if (dev->release != w1_slave_release)

		return 0;



	sl = dev_to_w1_slave(dev);



	switch (action) {

	case BUS_NOTIFY_ADD_DEVICE:

		/* Create our sysfs files before userspace is told about it */

		/* Create "name" entry */

		err = device_create_file(&sl->dev, &w1_slave_attr_name);

		if (err < 0) {

			dev_err(&sl->dev,

				"sysfs file creation for [%s] failed. err=%d\n",

				dev_name(&sl->dev), err);

			return err;

		}



		/* Create "id" entry */

		err = device_create_file(&sl->dev, &w1_slave_attr_id);

		if (err < 0) {

			dev_err(&sl->dev,

				"sysfs file creation for [%s] failed. err=%d\n",

				dev_name(&sl->dev), err);

			return err;

		}



		/* if the family driver needs to initialize something... */

		if (sl->family->fops && sl->family->fops->add_slave &&

		    ((err = sl->family->fops->add_slave(sl)) < 0)) {

			dev_err(&sl->dev,

				"sysfs file creation for [%s] failed. err=%d\n",

				dev_name(&sl->dev), err);

			return err;

		}



		break;

	case BUS_NOTIFY_DEL_DEVICE:

		/* Remove our sysfs files */

		if (sl->family->fops && sl->family->fops->remove_slave)

			sl->family->fops->remove_slave(sl);

		device_remove_file(&sl->dev, &w1_slave_attr_id);

		device_remove_file(&sl->dev, &w1_slave_attr_name);

		break;

	}

	return 0;

}



static struct notifier_block w1_bus_nb = {

	.notifier_call = w1_bus_notify,

};



static int __w1_attach_slave_device(struct w1_slave *sl)

{

	int err;
@@ -615,44 +682,13 @@ static int __w1_attach_slave_device(struct w1_slave *sl) 
		return err;

	}



	/* Create "name" entry */

	err = device_create_file(&sl->dev, &w1_slave_attr_name);

	if (err < 0) {

		dev_err(&sl->dev,

			"sysfs file creation for [%s] failed. err=%d\n",

			dev_name(&sl->dev), err);

		goto out_unreg;

	}



	/* Create "id" entry */

	err = device_create_file(&sl->dev, &w1_slave_attr_id);

	if (err < 0) {

		dev_err(&sl->dev,

			"sysfs file creation for [%s] failed. err=%d\n",

			dev_name(&sl->dev), err);

		goto out_rem1;

	}



	/* if the family driver needs to initialize something... */

	if (sl->family->fops && sl->family->fops->add_slave &&

	    ((err = sl->family->fops->add_slave(sl)) < 0)) {

		dev_err(&sl->dev,

			"sysfs file creation for [%s] failed. err=%d\n",

			dev_name(&sl->dev), err);

		goto out_rem2;

	}

	dev_set_uevent_suppress(&sl->dev, false);

	kobject_uevent(&sl->dev.kobj, KOBJ_ADD);



	list_add_tail(&sl->w1_slave_entry, &sl->master->slist);



	return 0;



out_rem2:

	device_remove_file(&sl->dev, &w1_slave_attr_id);

out_rem1:

	device_remove_file(&sl->dev, &w1_slave_attr_name);

out_unreg:

	device_unregister(&sl->dev);

	return err;

}



static int w1_attach_slave_device(struct w1_master *dev, struct w1_reg_num *rn)
@@ -723,16 +759,11 @@ void w1_slave_detach(struct w1_slave *sl) 


	list_del(&sl->w1_slave_entry);



	if (sl->family->fops && sl->family->fops->remove_slave)

		sl->family->fops->remove_slave(sl);



	memset(&msg, 0, sizeof(msg));

	memcpy(msg.id.id, &sl->reg_num, sizeof(msg.id));

	msg.type = W1_SLAVE_REMOVE;

	w1_netlink_send(sl->master, &msg);



	device_remove_file(&sl->dev, &w1_slave_attr_id);

	device_remove_file(&sl->dev, &w1_slave_attr_name);

	device_unregister(&sl->dev);



	wait_for_completion(&sl->released);
@@ -1017,6 +1048,10 @@ static int __init w1_init(void) 
		goto err_out_exit_init;

	}



	retval = bus_register_notifier(&w1_bus_type, &w1_bus_nb);

	if (retval)

		goto err_out_bus_unregister;



	retval = driver_register(&w1_master_driver);

	if (retval) {

		printk(KERN_ERR

CRA Git | Maintained and supported by SUSTech CRA and CCSE