devres: introduce API "devm_kstrdup"

This patch introduces "devm_kstrdup" API so that the
device's driver can allocate memory and copy string.
Signed-off-by: Manish Badarkhe <badarkhe.manish@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/base/devres.c

@@ -790,6 +790,32 @@ void * devm_kmalloc(struct device *dev, size_t size, gfp_t gfp)
 }
 EXPORT_SYMBOL_GPL(devm_kmalloc);
 
+/**
+ * devm_kstrdup - Allocate resource managed space and
+ *                copy an existing string into that.
+ * @dev: Device to allocate memory for
+ * @s: the string to duplicate
+ * @gfp: the GFP mask used in the devm_kmalloc() call when
+ *       allocating memory
+ * RETURNS:
+ * Pointer to allocated string on success, NULL on failure.
+ */
+char *devm_kstrdup(struct device *dev, const char *s, gfp_t gfp)
+{
+	size_t size;
+	char *buf;
+
+	if (!s)
+		return NULL;
+
+	size = strlen(s) + 1;
+	buf = devm_kmalloc(dev, size, gfp);
+	if (buf)
+		memcpy(buf, s, size);
+	return buf;
+}
+EXPORT_SYMBOL_GPL(devm_kstrdup);
+
 /**
  * devm_kfree - Resource-managed kfree
  * @dev: Device this memory belongs to

include/linux/device.h

@@ -626,6 +626,7 @@ static inline void *devm_kcalloc(struct device *dev,
 	return devm_kmalloc_array(dev, n, size, flags | __GFP_ZERO);
 }
 extern void devm_kfree(struct device *dev, void *p);
+extern char *devm_kstrdup(struct device *dev, const char *s, gfp_t gfp);
 
 void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res);
 void __iomem *devm_request_and_ioremap(struct device *dev,