Commit f2db85b6 authored by Saravana Kannan's avatar Saravana Kannan Committed by Greg Kroah-Hartman
Browse files

driver core: Avoid pointless deferred probe attempts 



There's no point in adding a device to the deferred probe list if we
know for sure that it doesn't have a matching driver. So, check if a
device can match with a driver before adding it to the deferred probe
list.

Signed-off-by: default avatarSaravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20210302211133.2244281-2-saravanak@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 01085e24

drivers/base/dd.c

+6 −0
Original line number Diff line number Diff line
@@ -122,6 +122,9 @@ static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func); 


void driver_deferred_probe_add(struct device *dev)

{

	if (!dev->can_match)

		return;



	mutex_lock(&deferred_probe_mutex);

	if (list_empty(&dev->p->deferred_probe)) {

		dev_dbg(dev, "Added to deferred list\n");
@@ -725,6 +728,7 @@ static int driver_probe_device(struct device_driver *drv, struct device *dev) 
	if (!device_is_registered(dev))

		return -ENODEV;



	dev->can_match = true;

	pr_debug("bus: '%s': %s: matched device %s with driver %s\n",

		 drv->bus->name, __func__, dev_name(dev), drv->name);
@@ -828,6 +832,7 @@ static int __device_attach_driver(struct device_driver *drv, void *_data) 
		return 0;

	} else if (ret == -EPROBE_DEFER) {

		dev_dbg(dev, "Device match requests probe deferral\n");

		dev->can_match = true;

		driver_deferred_probe_add(dev);

	} else if (ret < 0) {

		dev_dbg(dev, "Bus failed to match device: %d\n", ret);
@@ -1063,6 +1068,7 @@ static int __driver_attach(struct device *dev, void *data) 
		return 0;

	} else if (ret == -EPROBE_DEFER) {

		dev_dbg(dev, "Device match requests probe deferral\n");

		dev->can_match = true;

		driver_deferred_probe_add(dev);

	} else if (ret < 0) {

		dev_dbg(dev, "Bus failed to match device: %d\n", ret);

include/linux/device.h

+4 −0
Original line number Diff line number Diff line
@@ -439,6 +439,9 @@ struct dev_links_info { 
 * @state_synced: The hardware state of this device has been synced to match

 *		  the software state of this device by calling the driver/bus

 *		  sync_state() callback.

 * @can_match:	The device has matched with a driver at least once or it is in

 *		a bus (like AMBA) which can't check for matching drivers until

 *		other devices probe successfully.

 * @dma_coherent: this particular device is dma coherent, even if the

 *		architecture supports non-coherent devices.

 * @dma_ops_bypass: If set to %true then the dma_ops are bypassed for the
@@ -545,6 +548,7 @@ struct device { 
	bool			offline:1;

	bool			of_node_reused:1;

	bool			state_synced:1;

	bool			can_match:1;

#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \

    defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \

    defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)