Commit 6a6dfdf8 authored by Saravana Kannan's avatar Saravana Kannan Committed by Greg Kroah-Hartman
Browse files

driver core: fw_devlink: Allow marking a fwnode link as being part of a cycle 



To improve detection and handling of dependency cycles, we need to be
able to mark fwnode links as being part of cycles. fwnode links marked
as being part of a cycle should not block their consumers from probing.

Fixes: 2de9d8e0 ("driver core: fw_devlink: Improve handling of cyclic dependencies")
Signed-off-by: default avatarSaravana Kannan <saravanak@google.com>
Tested-by: default avatarColin Foster <colin.foster@in-advantage.com>
Tested-by: default avatarSudeep Holla <sudeep.holla@arm.com>
Tested-by: default avatarDouglas Anderson <dianders@chromium.org>
Tested-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Luca Weiss <luca.weiss@fairphone.com> # qcom/sm7225-fairphone-fp4
Link: https://lore.kernel.org/r/20230207014207.1678715-7-saravanak@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 67cad5c6

drivers/base/core.c

+40 −10
Original line number Diff line number Diff line
@@ -76,13 +76,15 @@ static bool fw_devlink_best_effort; 
 * are ignored and there is no reference counting.

 */

static int __fwnode_link_add(struct fwnode_handle *con,

			     struct fwnode_handle *sup)

			     struct fwnode_handle *sup, u8 flags)

{

	struct fwnode_link *link;



	list_for_each_entry(link, &sup->consumers, s_hook)

		if (link->consumer == con)

		if (link->consumer == con) {

			link->flags |= flags;

			return 0;

		}



	link = kzalloc(sizeof(*link), GFP_KERNEL);

	if (!link)
@@ -92,6 +94,7 @@ static int __fwnode_link_add(struct fwnode_handle *con, 
	INIT_LIST_HEAD(&link->s_hook);

	link->consumer = con;

	INIT_LIST_HEAD(&link->c_hook);

	link->flags = flags;



	list_add(&link->s_hook, &sup->consumers);

	list_add(&link->c_hook, &con->suppliers);
@@ -106,7 +109,7 @@ int fwnode_link_add(struct fwnode_handle *con, struct fwnode_handle *sup) 
	int ret;



	mutex_lock(&fwnode_link_lock);

	ret = __fwnode_link_add(con, sup);

	ret = __fwnode_link_add(con, sup, 0);

	mutex_unlock(&fwnode_link_lock);

	return ret;

}
@@ -126,6 +129,19 @@ static void __fwnode_link_del(struct fwnode_link *link) 
	kfree(link);

}



/**

 * __fwnode_link_cycle - Mark a fwnode link as being part of a cycle.

 * @link: the fwnode_link to be marked

 *

 * The fwnode_link_lock needs to be held when this function is called.

 */

static void __fwnode_link_cycle(struct fwnode_link *link)

{

	pr_debug("%pfwf: Relaxing link with %pfwf\n",

		 link->consumer, link->supplier);

	link->flags |= FWLINK_FLAG_CYCLE;

}



/**

 * fwnode_links_purge_suppliers - Delete all supplier links of fwnode_handle.

 * @fwnode: fwnode whose supplier links need to be deleted
@@ -199,7 +215,7 @@ static void __fwnode_links_move_consumers(struct fwnode_handle *from, 
	struct fwnode_link *link, *tmp;



	list_for_each_entry_safe(link, tmp, &from->consumers, s_hook) {

		__fwnode_link_add(link->consumer, to);

		__fwnode_link_add(link->consumer, to, link->flags);

		__fwnode_link_del(link);

	}

}
@@ -1041,6 +1057,21 @@ static bool dev_is_best_effort(struct device *dev) 
		(dev->fwnode && (dev->fwnode->flags & FWNODE_FLAG_BEST_EFFORT));

}



static struct fwnode_handle *fwnode_links_check_suppliers(

						struct fwnode_handle *fwnode)

{

	struct fwnode_link *link;



	if (!fwnode || fw_devlink_is_permissive())

		return NULL;



	list_for_each_entry(link, &fwnode->suppliers, c_hook)

		if (!(link->flags & FWLINK_FLAG_CYCLE))

			return link->supplier;



	return NULL;

}



/**

 * device_links_check_suppliers - Check presence of supplier drivers.

 * @dev: Consumer device.
@@ -1068,11 +1099,8 @@ int device_links_check_suppliers(struct device *dev) 
	 * probe.

	 */

	mutex_lock(&fwnode_link_lock);

	if (dev->fwnode && !list_empty(&dev->fwnode->suppliers) &&

	    !fw_devlink_is_permissive()) {

		sup_fw = list_first_entry(&dev->fwnode->suppliers,

					  struct fwnode_link,

					  c_hook)->supplier;

	sup_fw = fwnode_links_check_suppliers(dev->fwnode);

	if (sup_fw) {

		if (!dev_is_best_effort(dev)) {

			fwnode_ret = -EPROBE_DEFER;

			dev_err_probe(dev, -EPROBE_DEFER,
@@ -1261,7 +1289,9 @@ static ssize_t waiting_for_supplier_show(struct device *dev, 
	bool val;



	device_lock(dev);

	val = !list_empty(&dev->fwnode->suppliers);

	mutex_lock(&fwnode_link_lock);

	val = !!fwnode_links_check_suppliers(dev->fwnode);

	mutex_unlock(&fwnode_link_lock);

	device_unlock(dev);

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

}

include/linux/fwnode.h

+10 −1
Original line number Diff line number Diff line
@@ -18,7 +18,7 @@ struct fwnode_operations; 
struct device;



/*

 * fwnode link flags

 * fwnode flags

 *

 * LINKS_ADDED:	The fwnode has already be parsed to add fwnode links.

 * NOT_DEVICE:	The fwnode will never be populated as a struct device.
@@ -36,6 +36,7 @@ struct device; 
#define FWNODE_FLAG_INITIALIZED			BIT(2)

#define FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD	BIT(3)

#define FWNODE_FLAG_BEST_EFFORT			BIT(4)

#define FWNODE_FLAG_VISITED			BIT(5)



struct fwnode_handle {

	struct fwnode_handle *secondary;
@@ -46,11 +47,19 @@ struct fwnode_handle { 
	u8 flags;

};



/*

 * fwnode link flags

 *

 * CYCLE:	The fwnode link is part of a cycle. Don't defer probe.

 */

#define FWLINK_FLAG_CYCLE			BIT(0)



struct fwnode_link {

	struct fwnode_handle *supplier;

	struct list_head s_hook;

	struct fwnode_handle *consumer;

	struct list_head c_hook;

	u8 flags;

};



/**