diff mbox

[4/4] component: add support for releasing match data

Message ID E1a0tZt-0006Ej-9a@rmk-PC.arm.linux.org.uk (mailing list archive)
State New, archived
Headers show

Commit Message

Russell King Nov. 23, 2015, 4:02 p.m. UTC
The component helper treats the void match data pointer as an opaque
object which needs no further management.  When device nodes being
passed, this is not true: the caller should pass its refcount to the
component helper, and there should be a way to drop the refcount when
the matching information is destroyed.

This patch provides a per-match release method in addition to the match
method to solve this issue.  Rather than using component_match_add(),
users should use component_match_add_release() which takes an additional
function pointer for releasing this reference.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 drivers/base/component.c  | 101 ++++++++++++++++++++++++++++++----------------
 include/linux/component.h |  28 +++++++++----
 2 files changed, 87 insertions(+), 42 deletions(-)
diff mbox

Patch

diff --git a/drivers/base/component.c b/drivers/base/component.c
index d99b06b341fb..89f5cf68d80a 100644
--- a/drivers/base/component.c
+++ b/drivers/base/component.c
@@ -20,15 +20,18 @@ 
 
 struct component;
 
+struct component_match_array {
+	void *data;
+	int (*compare)(struct device *, void *);
+	void (*release)(struct device *, void *);
+	struct component *component;
+	bool duplicate;
+};
+
 struct component_match {
 	size_t alloc;
 	size_t num;
-	struct {
-		void *data;
-		int (*fn)(struct device *, void *);
-		struct component *component;
-		bool duplicate;
-	} compare[0];
+	struct component_match_array *compare;
 };
 
 struct master {
@@ -92,6 +95,7 @@  static int find_components(struct master *master)
 	 * any components which are found to this master.
 	 */
 	for (i = 0; i < match->num; i++) {
+		struct component_match_array *mc = &match->compare[i];
 		struct component *c;
 
 		dev_dbg(master->dev, "Looking for component %zu\n", i);
@@ -99,8 +103,7 @@  static int find_components(struct master *master)
 		if (match->compare[i].component)
 			continue;
 
-		c = find_component(master, match->compare[i].fn,
-				   match->compare[i].data);
+		c = find_component(master, mc->compare, mc->data);
 		if (!c) {
 			ret = -ENXIO;
 			break;
@@ -192,41 +195,55 @@  static void take_down_master(struct master *master)
 	}
 }
 
-static size_t component_match_size(size_t num)
+static void component_match_release(struct device *master,
+	struct component_match *match)
+{
+	unsigned int i;
+
+	for (i = 0; i < match->num; i++) {
+		struct component_match_array *mc = &match->compare[i];
+
+		if (mc->release)
+			mc->release(master, mc->data);
+	}
+}
+
+static void devm_component_match_release(struct device *dev, void *res)
 {
-	return offsetof(struct component_match, compare[num]);
+	component_match_release(dev, res);
 }
 
-static struct component_match *component_match_realloc(struct device *dev,
+static int component_match_realloc(struct device *dev,
 	struct component_match *match, size_t num)
 {
-	struct component_match *new;
+	struct component_match_array *new;
 
-	if (match && match->alloc == num)
-		return match;
+	if (match->alloc == num)
+		return 0;
 
-	new = devm_kmalloc(dev, component_match_size(num), GFP_KERNEL);
+	new = devm_kmalloc_array(dev, num, sizeof(*new), GFP_KERNEL);
 	if (!new)
-		return ERR_PTR(-ENOMEM);
+		return -ENOMEM;
 
-	if (match) {
-		memcpy(new, match, component_match_size(min(match->num, num)));
-		devm_kfree(dev, match);
-	} else {
-		new->num = 0;
+	if (match->compare) {
+		memcpy(new, match->compare, sizeof(*new) *
+					    min(match->num, num));
+		devm_kfree(dev, match->compare);
 	}
+	match->compare = new;
+	match->alloc = num;
 
-	new->alloc = num;
-
-	return new;
+	return 0;
 }
 
 /*
- * Add a component to be matched.
+ * Add a component to be matched, with a release function.
  *
  * The match array is first created or extended if necessary.
  */
-void component_match_add(struct device *dev, struct component_match **matchptr,
+void component_match_add_release(struct device *master,
+	struct component_match **matchptr,
+	void (*release)(struct device *, void *),
 	int (*compare)(struct device *, void *), void *compare_data)
 {
 	struct component_match *match = *matchptr;
@@ -234,23 +251,37 @@  void component_match_add(struct device *dev, struct component_match **matchptr,
 	if (IS_ERR(match))
 		return;
 
-	if (!match || match->num == match->alloc) {
-		size_t new_size = match ? match->alloc + 16 : 15;
+	if (!match) {
+		match = devres_alloc(devm_component_match_release,
+				     sizeof(*match), GFP_KERNEL);
+		if (!match) {
+			*matchptr = ERR_PTR(-ENOMEM);
+			return;
+		}
 
-		match = component_match_realloc(dev, match, new_size);
+		devres_add(master, match);
 
 		*matchptr = match;
+	}
+
+	if (match->num == match->alloc) {
+		size_t new_size = match ? match->alloc + 16 : 15;
+		int ret;
 
-		if (IS_ERR(match))
+		ret = component_match_realloc(master, match, new_size);
+		if (ret) {
+			*matchptr = ERR_PTR(ret);
 			return;
+		}
 	}
 
-	match->compare[match->num].fn = compare;
+	match->compare[match->num].compare = compare;
+	match->compare[match->num].release = release;
 	match->compare[match->num].data = compare_data;
 	match->compare[match->num].component = NULL;
 	match->num++;
 }
-EXPORT_SYMBOL(component_match_add);
+EXPORT_SYMBOL(component_match_add_release);
 
 int component_master_add_with_match(struct device *dev,
 	const struct component_master_ops *ops,
@@ -260,9 +291,9 @@  int component_master_add_with_match(struct device *dev,
 	int ret;
 
 	/* Reallocate the match array for its true size */
-	match = component_match_realloc(dev, match, match->num);
-	if (IS_ERR(match))
-		return PTR_ERR(match);
+	ret = component_match_realloc(dev, match, match->num);
+	if (ret)
+		return ret;
 
 	master = kzalloc(sizeof(*master), GFP_KERNEL);
 	if (!master)
diff --git a/include/linux/component.h b/include/linux/component.h
index 71c434a6a5ee..a559eebc0e0f 100644
--- a/include/linux/component.h
+++ b/include/linux/component.h
@@ -1,24 +1,28 @@ 
 #ifndef COMPONENT_H
 #define COMPONENT_H
 
+#include <linux/stddef.h>
+
 struct device;
 
 struct component_ops {
-	int (*bind)(struct device *, struct device *, void *);
-	void (*unbind)(struct device *, struct device *, void *);
+	int (*bind)(struct device *comp, struct device *master,
+		    void *master_data);
+	void (*unbind)(struct device *comp, struct device *master,
+		       void *master_data);
 };
 
 int component_add(struct device *, const struct component_ops *);
 void component_del(struct device *, const struct component_ops *);
 
-int component_bind_all(struct device *, void *);
-void component_unbind_all(struct device *, void *);
+int component_bind_all(struct device *master, void *master_data);
+void component_unbind_all(struct device *master, void *master_data);
 
 struct master;
 
 struct component_master_ops {
-	int (*bind)(struct device *);
-	void (*unbind)(struct device *);
+	int (*bind)(struct device *master);
+	void (*unbind)(struct device *master);
 };
 
 void component_master_del(struct device *,
@@ -28,7 +32,17 @@  struct component_match;
 
 int component_master_add_with_match(struct device *,
 	const struct component_master_ops *, struct component_match *);
-void component_match_add(struct device *, struct component_match **,
+void component_match_add_release(struct device *master,
+	struct component_match **matchptr,
+	void (*release)(struct device *, void *),
 	int (*compare)(struct device *, void *), void *compare_data);
 
+static inline void component_match_add(struct device *master,
+	struct component_match **matchptr,
+	int (*compare)(struct device *, void *), void *compare_data)
+{
+	component_match_add_release(master, matchptr, NULL, compare,
+				    compare_data);
+}
+
 #endif