On 2017-06-22 02:43, Mark Rutland wrote:
On Tue, Jun 20, 2017 at 04:12:32PM -0700, David Rientjes wrote:
On Tue, 20 Jun 2017, Mark Rutland wrote:

> As with my reply to David, my preference would be that we:
>
> 1) Align compiler-clang.h with the compiler-gcc.h inlining behaviour, so
>    that things work by default.
>
> 2) Fix up the arm64 core code (and drivers for architected / common
>    peripherals) to use __always_inline where we always require inlining.
>
> 3) Have arm64 select CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING, and have
>    people test-build configurations with CONFIG_OPTIMIZE_INLINING, with
>    both GCC and clang.
>
> 4) Fix up drivers, etc, as appropriate.
>
> 5) Once that's largely stable, and if there's a benefit, have arm64
>    select CONFIG_OPTIMIZE_INLINING by default.
>
> That should avoid undue breakage, while enabling this ASAP.
>

Sounds good, but I think we should simply deal with the
__attribute__((unused)) needed for clang as part of compiler-gcc.h by
simply adding it to the inline override there to avoid duplicated code.

Agreed. That looks much better.

Thanks,
Mark.


diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
--- a/include/linux/compiler-clang.h
+++ b/include/linux/compiler-clang.h
@@ -15,11 +15,3 @@
  * with any version that can compile the kernel
  */
#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
-
-/*
- * GCC does not warn about unused static inline functions for
- * -Wunused-function. This turns out to avoid the need for complex #ifdef
- * directives.  Suppress the warning in clang as well.
- */
-#undef inline
-#define inline inline __attribute__((unused)) notrace
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 0efef9cf014f..71fe0994cf1a 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -66,18 +66,22 @@

 /*
  * Force always-inline if the user requests it so via the .config,
- * or if gcc is too old:
+ * or if gcc is too old.
+ * GCC does not warn about unused static inline functions for
+ * -Wunused-function. This turns out to avoid the need for complex #ifdef + * directives. Suppress the warning in clang as well by using "unused"
+ * function attribute, which is redundant but not harmful for gcc.
  */
 #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) ||               \
     !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
-#define inline         inline          __attribute__((always_inline)) notrace
-#define __inline__     __inline__      __attribute__((always_inline)) notrace
-#define __inline       __inline        __attribute__((always_inline)) notrace
+#define inline inline          __attribute__((always_inline,unused)) notrace
+#define __inline__ __inline__ __attribute__((always_inline,unused)) notrace +#define __inline __inline __attribute__((always_inline,unused)) notrace
 #else
 /* A lot of inline functions can cause havoc with function tracing */
-#define inline         inline          notrace
-#define __inline__     __inline__      notrace
-#define __inline       __inline        notrace
+#define inline inline          __attribute__((unused)) notrace
+#define __inline__ __inline__  __attribute__((unused)) notrace
+#define __inline __inline      __attribute__((unused)) notrace
 #endif

 #define __always_inline        inline __attribute__((always_inline))
Hi David,

I just want to cross check with you.
Do you want me to update this change in next patch set ? Or are you going to add this ?

-Thanks, Prasad
--
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