devres: Add devm_kasprintf and devm_kvasprintf API

devm_kasprintf() and devm_kvasprintf() are the managed counterparts
for kasprintf() and kvasprintf().
Signed-off-by: NHimangi Saraogi <himangi774@gmail.com>
Acked-by: NJulia Lawall <julia.lawall@lip6.fr>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/devres.c

@@ -816,6 +816,61 @@ char *devm_kstrdup(struct device *dev, const char *s, gfp_t gfp)
 }
 EXPORT_SYMBOL_GPL(devm_kstrdup);
 
+/**
+ * devm_kvasprintf - Allocate resource managed space
+ *			for the formatted string.
+ * @dev: Device to allocate memory for
+ * @gfp: the GFP mask used in the devm_kmalloc() call when
+ *       allocating memory
+ * @fmt: the formatted string to duplicate
+ * @ap: the list of tokens to be placed in the formatted string
+ * RETURNS:
+ * Pointer to allocated string on success, NULL on failure.
+ */
+char *devm_kvasprintf(struct device *dev, gfp_t gfp, const char *fmt,
+		      va_list ap)
+{
+	unsigned int len;
+	char *p;
+	va_list aq;
+
+	va_copy(aq, ap);
+	len = vsnprintf(NULL, 0, fmt, aq);
+	va_end(aq);
+
+	p = devm_kmalloc(dev, len+1, gfp);
+	if (!p)
+		return NULL;
+
+	vsnprintf(p, len+1, fmt, ap);
+
+	return p;
+}
+EXPORT_SYMBOL(devm_kvasprintf);
+
+/**
+ * devm_kasprintf - Allocate resource managed space
+ *		and copy an existing formatted string into that
+ * @dev: Device to allocate memory for
+ * @gfp: the GFP mask used in the devm_kmalloc() call when
+ *       allocating memory
+ * @fmt: the string to duplicate
+ * RETURNS:
+ * Pointer to allocated string on success, NULL on failure.
+ */
+char *devm_kasprintf(struct device *dev, gfp_t gfp, const char *fmt, ...)
+{
+	va_list ap;
+	char *p;
+
+	va_start(ap, fmt);
+	p = devm_kvasprintf(dev, gfp, fmt, ap);
+	va_end(ap);
+
+	return p;
+}
+EXPORT_SYMBOL_GPL(devm_kasprintf);
+
 /**
  * devm_kfree - Resource-managed kfree
  * @dev: Device this memory belongs to

include/linux/device.h

@@ -605,6 +605,10 @@ extern int devres_release_group(struct device *dev, void *id);
 
 /* managed devm_k.alloc/kfree for device drivers */
 extern void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp);
+extern char *devm_kvasprintf(struct device *dev, gfp_t gfp, const char *fmt,
+			     va_list ap);
+extern char *devm_kasprintf(struct device *dev, gfp_t gfp,
+			    const char *fmt, ...);
 static inline void *devm_kzalloc(struct device *dev, size_t size, gfp_t gfp)
 {
 	return devm_kmalloc(dev, size, gfp | __GFP_ZERO);