driver core: Introduce device_find_any_child() helper

[ Upstream commit 82b070beae1ef55b0049768c8dc91d87565bb191 ]

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@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220610120219.18988-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 27aabf27fd01 ("Bluetooth: fix use-after-free in device_for_each_child()")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/base/core.c b/drivers/base/core.c
index d995d768c362acebcf67fc0e65f58b49909f1f23..4fc62624a95e2c152526ff8051176ec9a7eaa97b 100644 (file)
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -3829,6 +3829,26 @@ 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 3e04bd84f126498c63569c7387933f6e9d6a01a4..440c9f1a3f35010b95292934f8205332df5c25a1 100644 (file)
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -830,6 +830,8 @@ struct device *device_find_child(struct device *dev, void *data,
                                 int (*match)(struct device *dev, void *data));
 struct device *device_find_child_by_name(struct device *parent,
                                         const char *name);
+struct device *device_find_any_child(struct device *parent);
+
 int device_rename(struct device *dev, const char *new_name);
 int device_move(struct device *dev, struct device *new_parent,
                enum dpm_order dpm_order);