devres: Improve devm_kasprintf()/kvasprintf() support

- Add devm_kasprintf()/kvasprintf(), introduced by commit
    75f2a4ead5 ("devres: Add
    devm_kasprintf and devm_kvasprintf API"), to
    Documentation/driver-model/devres.txt,
  - Improve kernel doc: the string is not an existing formatted string,
    but is formatted into the newly-allocated buffer,
  - Add a __printf() annotation to devm_kasprintf(), so the compiler
    will verify the format string argument types.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/driver-model/devres.txt

@@ -293,12 +293,14 @@ MDIO
 MEM
   devm_free_pages()
   devm_get_free_pages()
+  devm_kasprintf()
   devm_kcalloc()
   devm_kfree()
   devm_kmalloc()
   devm_kmalloc_array()
   devm_kmemdup()
   devm_kstrdup()
+  devm_kvasprintf()
   devm_kzalloc()
 
 PCI

drivers/base/devres.c

@@ -817,13 +817,13 @@ 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.
+ * devm_kvasprintf - Allocate resource managed space and format a string
+ *		     into that.
  * @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
+ * @fmt: The printf()-style format string
+ * @ap: Arguments for the format string
  * RETURNS:
  * Pointer to allocated string on success, NULL on failure.
  */
@@ -849,12 +849,13 @@ char *devm_kvasprintf(struct device *dev, gfp_t gfp, const char *fmt,
 EXPORT_SYMBOL(devm_kvasprintf);
 
 /**
- * devm_kasprintf - Allocate resource managed space
- *		and copy an existing formatted string into that
+ * devm_kasprintf - Allocate resource managed space and format a 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
+ * @fmt: The printf()-style format string
+ * @...: Arguments for the format string
  * RETURNS:
  * Pointer to allocated string on success, NULL on failure.
  */

include/linux/device.h

@@ -607,8 +607,8 @@ extern int devres_release_group(struct device *dev, void *id);
 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, ...);
+extern __printf(3, 4)
+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);