Commit bcbbcfd5 authored by Saravana Kannan's avatar Saravana Kannan Committed by Greg Kroah-Hartman
Browse files

driver core: Allow a device to wait on optional suppliers 



Before this change, if a device is waiting on suppliers, it's assumed
that all those suppliers are needed for the device to probe
successfully. This change allows marking a devices as waiting only on
optional suppliers. This allows a device to wait on suppliers (and link
to them as soon as they are available) without preventing the device
from being probed.

Signed-off-by: default avatarSaravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20191028220027.251605-3-saravanak@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 05ef983e

drivers/base/core.c

+25 −3
Original line number Diff line number Diff line
@@ -480,13 +480,25 @@ EXPORT_SYMBOL_GPL(device_link_add); 
 * This function is NOT meant to be called from the probe function of the

 * consumer but rather from code that creates/adds the consumer device.

 */

static void device_link_wait_for_supplier(struct device *consumer)

static void device_link_wait_for_supplier(struct device *consumer,

					  bool need_for_probe)

{

	mutex_lock(&wfs_lock);

	list_add_tail(&consumer->links.needs_suppliers, &wait_for_suppliers);

	consumer->links.need_for_probe = need_for_probe;

	mutex_unlock(&wfs_lock);

}



static void device_link_wait_for_mandatory_supplier(struct device *consumer)

{

	device_link_wait_for_supplier(consumer, true);

}



static void device_link_wait_for_optional_supplier(struct device *consumer)

{

	device_link_wait_for_supplier(consumer, false);

}



/**

 * device_link_add_missing_supplier_links - Add links from consumer devices to

 *					    supplier devices, leaving any
@@ -656,7 +668,8 @@ int device_links_check_suppliers(struct device *dev) 
	 * probe.

	 */

	mutex_lock(&wfs_lock);

	if (!list_empty(&dev->links.needs_suppliers)) {

	if (!list_empty(&dev->links.needs_suppliers) &&

	    dev->links.need_for_probe) {

		mutex_unlock(&wfs_lock);

		return -EPROBE_DEFER;

	}
@@ -760,6 +773,15 @@ void device_links_driver_bound(struct device *dev) 
{

	struct device_link *link;



	/*

	 * If a device probes successfully, it's expected to have created all

	 * the device links it needs to or make new device links as it needs

	 * them. So, it no longer needs to wait on any suppliers.

	 */

	mutex_lock(&wfs_lock);

	list_del_init(&dev->links.needs_suppliers);

	mutex_unlock(&wfs_lock);



	device_links_write_lock();



	list_for_each_entry(link, &dev->links.consumers, s_node) {
@@ -2393,7 +2415,7 @@ int device_add(struct device *dev) 


	if (fwnode_has_op(dev->fwnode, add_links)

	    && fwnode_call_int_op(dev->fwnode, add_links, dev))

		device_link_wait_for_supplier(dev);

		device_link_wait_for_mandatory_supplier(dev, true);



	bus_probe_device(dev);

	if (parent)

include/linux/device.h

+3 −0
Original line number Diff line number Diff line
@@ -1155,6 +1155,8 @@ enum dl_dev_state { 
 * @consumers: List of links to consumer devices.

 * @needs_suppliers: Hook to global list of devices waiting for suppliers.

 * @defer_sync: Hook to global list of devices that have deferred sync_state.

 * @need_for_probe: If needs_suppliers is on a list, this indicates if the

 *		    suppliers are needed for probe or not.

 * @status: Driver status information.

 */

struct dev_links_info {
@@ -1162,6 +1164,7 @@ struct dev_links_info { 
	struct list_head consumers;

	struct list_head needs_suppliers;

	struct list_head defer_sync;

	bool need_for_probe;

	enum dl_dev_state status;

};

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