devres: introduce API "devm_kmemdup

Introduce devm_kmemdup, which uses resource managed kmalloc.
There are several request from maintainers to add this instead
of using kmemdup.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Documentation/driver-model/devres.txt

@@ -236,6 +236,7 @@ certainly invest a bit more effort into libata core layer).
 MEM
   devm_kzalloc()
   devm_kfree()
+  devm_kmemdup()
 
 IIO
   devm_iio_device_alloc()

drivers/base/devres.c

@@ -831,3 +831,24 @@ void devm_kfree(struct device *dev, void *p)
 	WARN_ON(rc);
 }
 EXPORT_SYMBOL_GPL(devm_kfree);
+
+/**
+ * devm_kmemdup - Resource-managed kmemdup
+ * @dev: Device this memory belongs to
+ * @src: Memory region to duplicate
+ * @len: Memory region length
+ * @gfp: GFP mask to use
+ *
+ * Duplicate region of a memory using resource managed kmalloc
+ */
+void *devm_kmemdup(struct device *dev, const void *src, size_t len, gfp_t gfp)
+{
+	void *p;
+
+	p = devm_kmalloc(dev, len, gfp);
+	if (p)
+		memcpy(p, src, len);
+
+	return p;
+}
+EXPORT_SYMBOL_GPL(devm_kmemdup);

include/linux/device.h

@@ -623,6 +623,8 @@ static inline void *devm_kcalloc(struct device *dev,
 }
 extern void devm_kfree(struct device *dev, void *p);
 extern char *devm_kstrdup(struct device *dev, const char *s, gfp_t gfp);
+extern void *devm_kmemdup(struct device *dev, const void *src, size_t len,
+			  gfp_t gfp);
 
 void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res);
 void __iomem *devm_request_and_ioremap(struct device *dev,