Re: [PATCH] net: bcmgenet: Fix NULL vs IS_ERR() checking

[Joe Perches <joe@perches.com>]

On Sat, 2021-12-11 at 14:01 +0000, Miaoqian Lin wrote:
> The phy_attach() function does not return NULL. It returns error pointers.

Perhaps all the functions that return error pointers rather than
NULL on error should be marked with a special attribute:

Something like:

#define __returns_nonnull	__attribute__((__returns_nonnull__))

---

 include/linux/compiler_attributes.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h
index 37e2600202216..e2351a36dda97 100644
--- a/include/linux/compiler_attributes.h
+++ b/include/linux/compiler_attributes.h
@@ -250,6 +250,18 @@
 # define __no_profile
 #endif
 
+/*
+ * Optional: only supported since GCC >= 5.x
+ *
+ *      gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-returns_005fnonnull-function-attribute
+ *    clang: https://clang.llvm.org/docs/AttributeReference.html#returns-nonnull
+ */
+#if __has_attribute(__returns_nonnull__)
+# define __returns_nonnull		__attribute__((__returns_nonnull__))
+#else
+# define __returns_nonnull
+#endif
+
 /*
  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute
  * clang: https://clang.llvm.org/docs/AttributeReference.html#noreturn