Commit 2451e746 authored by Saravana Kannan's avatar Saravana Kannan Committed by Greg Kroah-Hartman
Browse files

driver core: Avoid deferred probe due to fw_devlink_pause/resume() 



With the earlier patch in this series, all devices that deferred probe
due to fw_devlink_pause() will have their probes delayed till the
deferred probe thread is kicked off during late_initcall. This will also
affect all their consumers.

This delayed probing in unnecessary. So this patch just keeps track of
the devices that had their probe deferred due to fw_devlink_pause() and
attempts to probe them once during fw_devlink_resume().

Fixes: 716a7a25 ("driver core: fw_devlink: Add support for batching fwnode parsing")
Signed-off-by: default avatarSaravana Kannan <saravanak@google.com>
Tested-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200701194259.3337652-4-saravanak@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ec7bd784

drivers/base/core.c

+21 −0
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ static DEFINE_MUTEX(wfs_lock); 
static LIST_HEAD(deferred_sync);

static unsigned int defer_sync_state_count = 1;

static unsigned int defer_fw_devlink_count;

static LIST_HEAD(deferred_fw_devlink);

static DEFINE_MUTEX(defer_fw_devlink_lock);

static bool fw_devlink_is_permissive(void);
@@ -1244,6 +1245,12 @@ static void fw_devlink_link_device(struct device *dev) 
			fw_ret = -EAGAIN;

	} else {

		fw_ret = -ENODEV;

		/*

		 * defer_hook is not used to add device to deferred_sync list

		 * until device is bound. Since deferred fw devlink also blocks

		 * probing, same list hook can be used for deferred_fw_devlink.

		 */

		list_add_tail(&dev->links.defer_hook, &deferred_fw_devlink);

	}



	if (fw_ret == -ENODEV)
@@ -1312,6 +1319,9 @@ void fw_devlink_pause(void) 
 */

void fw_devlink_resume(void)

{

	struct device *dev, *tmp;

	LIST_HEAD(probe_list);



	mutex_lock(&defer_fw_devlink_lock);

	if (!defer_fw_devlink_count) {

		WARN(true, "Unmatched fw_devlink pause/resume!");
@@ -1323,8 +1333,19 @@ void fw_devlink_resume(void) 
		goto out;



	device_link_add_missing_supplier_links();

	list_splice_tail_init(&deferred_fw_devlink, &probe_list);

out:

	mutex_unlock(&defer_fw_devlink_lock);



	/*

	 * bus_probe_device() can cause new devices to get added and they'll

	 * try to grab defer_fw_devlink_lock. So, this needs to be done outside

	 * the defer_fw_devlink_lock.

	 */

	list_for_each_entry_safe(dev, tmp, &probe_list, links.defer_hook) {

		list_del_init(&dev->links.defer_hook);

		bus_probe_device(dev);

	}

}

/* Device links support end. */

include/linux/device.h

+2 −1
Original line number Diff line number Diff line
@@ -433,7 +433,8 @@ enum dl_dev_state { 
 * @suppliers: List of links to supplier devices.

 * @consumers: List of links to consumer devices.

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

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

 * @defer_hook: Hook to global list of devices that have deferred sync_state or

 *		deferred fw_devlink.

 * @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.

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