[PATCH v2 01/32] driver core: Constify API device_find_child()

[Zijun Hu <zijun_hu@xxxxxxxxxx>]

From: Zijun Hu <quic_zijuhu@xxxxxxxxxxx>

Constify the following API:
struct device *device_find_child(struct device *dev, void *data,
		int (*match)(struct device *dev, void *data));
To :
struct device *device_find_child(struct device *dev, const void *data,
                                 device_match_t match);
typedef int (*device_match_t)(struct device *dev, const void *data);
with the following reasons:

- Protect caller's match data @*data which is for comparison and lookup
  and the API does not actually need to modify @*data.

- Make the API's parameters (@match)() and @data have the same type as
  all of other device finding APIs (bus|class|driver)_find_device().

- All kinds of existing device match functions can be directly taken
  as the API's argument, they were exported by driver core.

Now, no (*match)() argument of the API usages is modifying @*data in
current kernel tree, so it is safe to constify the API.

Signed-off-by: Zijun Hu <quic_zijuhu@xxxxxxxxxxx>
---
 drivers/base/core.c    | 11 +++--------
 include/linux/device.h |  4 ++--
 2 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 94865c9d8adcf5f2ce5002ffd7bf0ef4fc85e4d7..a122ea1d84a3b08fce16dd1abdfa7746d31dc430 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -4079,8 +4079,8 @@ EXPORT_SYMBOL_GPL(device_for_each_child_reverse_from);
  *
  * NOTE: you will need to drop the reference with put_device() after use.
  */
-struct device *device_find_child(struct device *parent, void *data,
-				 int (*match)(struct device *dev, void *data))
+struct device *device_find_child(struct device *parent, const void *data,
+				 device_match_t match)
 {
 	struct klist_iter i;
 	struct device *child;
@@ -4125,11 +4125,6 @@ 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
@@ -4141,7 +4136,7 @@ static int match_any(struct device *dev, void *unused)
  */
 struct device *device_find_any_child(struct device *parent)
 {
-	return device_find_child(parent, NULL, match_any);
+	return device_find_child(parent, NULL, device_match_any);
 }
 EXPORT_SYMBOL_GPL(device_find_any_child);
 
diff --git a/include/linux/device.h b/include/linux/device.h
index 667cb6db9019349c9db0233acf9e78ff6a6d9625..0e0bc9bfe0d15a8734bf3d34106300f4df6b5364 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -1081,8 +1081,8 @@ int device_for_each_child_reverse(struct device *dev, void *data,
 int device_for_each_child_reverse_from(struct device *parent,
 				       struct device *from, const void *data,
 				       int (*fn)(struct device *, const void *));
-struct device *device_find_child(struct device *dev, void *data,
-				 int (*match)(struct device *dev, void *data));
+struct device *device_find_child(struct device *dev, const void *data,
+				 device_match_t match);
 struct device *device_find_child_by_name(struct device *parent,
 					 const char *name);
 struct device *device_find_any_child(struct device *parent);

-- 
2.34.1