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Commit 86cf4134 authored by Saravana Kannan's avatar Saravana Kannan
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BACKPORT: driver core: Add waiting_for_supplier sysfs file for devices 



This would be useful to check if a device is not probing because it's
waiting for a supplier to be added and then linked to before it can
probe.

To reduce sysfs clutter, this file is added only if it can ever be 1.
So, if fw_devlink is disabled or set to permissive, this file is not
added. Also, this file is removed once the device probes as it's no
longer relevant.

Signed-off-by: default avatarSaravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20200521191800.136035-4-saravanak@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit da6d647598a6d182eb6a0344a7b14ae005244399)
[Conflicts due to missing fw_devlink_is_permissive() and fw_devlink_flags]
Signed-off-by: default avatarSaravana Kannan <saravanak@google.com>
Bug: 163090256
Change-Id: Ief4b9e35aff600f2eb88d15839e98a610f1c252f
parent e157d387

Documentation/ABI/testing/sysfs-devices-waiting_for_supplier

0 → 100644
+17 −0
Original line number Diff line number Diff line 
What:		/sys/devices/.../waiting_for_supplier

Date:		May 2020

Contact:	Saravana Kannan <saravanak@google.com>

Description:

		The /sys/devices/.../waiting_for_supplier attribute is only

		present when fw_devlink kernel command line option is enabled

		and is set to something stricter than "permissive".  It is

		removed once a device probes successfully (because the

		information is no longer relevant). The number read from it (0

		or 1) reflects whether the device is waiting for one or more

		suppliers to be added and then linked to using device links

		before the device can probe.



		A value of 0 means the device is not waiting for any suppliers

		to be added before it can probe.  A value of 1 means the device

		is waiting for one or more suppliers to be added before it can

		probe.

drivers/base/core.c

+24 −0
Original line number Diff line number Diff line
@@ -1041,6 +1041,22 @@ static void device_link_drop_managed(struct device_link *link) 
	kref_put(&link->kref, __device_link_del);

}



static ssize_t waiting_for_supplier_show(struct device *dev,

					 struct device_attribute *attr,

					 char *buf)

{

	bool val;



	device_lock(dev);

	mutex_lock(&wfs_lock);

	val = !list_empty(&dev->links.needs_suppliers)

	      && dev->links.need_for_probe;

	mutex_unlock(&wfs_lock);

	device_unlock(dev);

	return sprintf(buf, "%u\n", val);

}

static DEVICE_ATTR_RO(waiting_for_supplier);



/**

 * device_links_driver_bound - Update device links after probing its driver.

 * @dev: Device to update the links for.
@@ -1065,6 +1081,7 @@ void device_links_driver_bound(struct device *dev) 
	mutex_lock(&wfs_lock);

	list_del_init(&dev->links.needs_suppliers);

	mutex_unlock(&wfs_lock);

	device_remove_file(dev, &dev_attr_waiting_for_supplier);



	device_links_write_lock();
@@ -2128,8 +2145,14 @@ static int device_add_attrs(struct device *dev) 
			goto err_remove_dev_groups;

	}



	error = device_create_file(dev, &dev_attr_waiting_for_supplier);

	if (error)

		goto err_remove_dev_online;



	return 0;



 err_remove_dev_online:

	device_remove_file(dev, &dev_attr_online);

 err_remove_dev_groups:

	device_remove_groups(dev, dev->groups);

 err_remove_type_groups:
@@ -2147,6 +2170,7 @@ static void device_remove_attrs(struct device *dev) 
	struct class *class = dev->class;

	const struct device_type *type = dev->type;



	device_remove_file(dev, &dev_attr_waiting_for_supplier);

	device_remove_file(dev, &dev_attr_online);

	device_remove_groups(dev, dev->groups);