[SRU][F][PATCH 1/2] driver core: Introduce device_find_any_child() helper

[Massimiliano Pellizzer]

From: Andy Shevchenko <andriy.shevchenko at linux.intel.com>

There are several places in the kernel where this kind of functionality is
being used. Provide a generic helper for such cases.

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
Link: https://lore.kernel.org/r/20220610120219.18988-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(backported from commit 82b070beae1ef55b0049768c8dc91d87565bb191)
[mpellizzer: backported considering missing commit 67dd077239690, and
therefore keeping the attribute 'extern' in the function prototype]
CVE-2024-53237
Signed-off-by: Massimiliano Pellizzer <massimiliano.pellizzer at canonical.com>
---
 drivers/base/core.c    | 20 ++++++++++++++++++++
 include/linux/device.h |  1 +
 2 files changed, 21 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 4a69b2d177a8f..1c1556933f04b 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -2621,6 +2621,26 @@ struct device *device_find_child_by_name(struct device *parent,
 }
 EXPORT_SYMBOL_GPL(device_find_child_by_name);
 
+static int match_any(struct device *dev, void *unused)
+{
+	return 1;
+}
+
+/**
+ * device_find_any_child - device iterator for locating a child device, if any.
+ * @parent: parent struct device
+ *
+ * This is similar to the device_find_child() function above, but it
+ * returns a reference to a child device, if any.
+ *
+ * NOTE: you will need to drop the reference with put_device() after use.
+ */
+struct device *device_find_any_child(struct device *parent)
+{
+	return device_find_child(parent, NULL, match_any);
+}
+EXPORT_SYMBOL_GPL(device_find_any_child);
+
 int __init devices_init(void)
 {
 	devices_kset = kset_create_and_add("devices", &device_uevent_ops, NULL);
diff --git a/include/linux/device.h b/include/linux/device.h
index 99638b92fa5c4..f7825a8a10a1b 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -1510,6 +1510,7 @@ extern struct device *device_find_child(struct device *dev, void *data,
 				int (*match)(struct device *dev, void *data));
 extern struct device *device_find_child_by_name(struct device *parent,
 						const char *name);
+extern struct device *device_find_any_child(struct device *parent);
 extern int device_rename(struct device *dev, const char *new_name);
 extern int device_move(struct device *dev, struct device *new_parent,
 		       enum dpm_order dpm_order);
-- 
2.43.0