diff options
| author | David Rientjes <[email protected]> | 2017-07-06 15:35:24 -0700 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2017-07-06 16:24:29 -0700 |
| commit | 9a04dbcfb33b4012d0ce8c0282f1e3ca694675b1 (patch) | |
| tree | ec802cb076b875d2e8259de087d8cd186cfce70f /include/linux/compiler-gcc.h | |
| parent | 9ced560b82606b35adb33a27012a148d418a4c1f (diff) | |
compiler, clang: always inline when CONFIG_OPTIMIZE_INLINING is disabled
The motivation for commit abb2ea7dfd82 ("compiler, clang: suppress
warning for unused static inline functions") was to suppress clang's
warnings about unused static inline functions.
For configs without CONFIG_OPTIMIZE_INLINING enabled, such as any non-x86
architecture, `inline' in the kernel implies that
__attribute__((always_inline)) is used.
Some code depends on that behavior, see
https://lkml.org/lkml/2017/6/13/918:
net/built-in.o: In function `__xchg_mb':
arch/arm64/include/asm/cmpxchg.h:99: undefined reference to `__compiletime_assert_99'
arch/arm64/include/asm/cmpxchg.h:99: undefined reference to `__compiletime_assert_99
The full fix would be to identify these breakages and annotate the
functions with __always_inline instead of `inline'. But since we are
late in the 4.12-rc cycle, simply carry forward the forced inlining
behavior and work toward moving arm64, and other architectures, toward
CONFIG_OPTIMIZE_INLINING behavior.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: David Rientjes <[email protected]>
Reported-by: Sodagudi Prasad <[email protected]>
Tested-by: Sodagudi Prasad <[email protected]>
Tested-by: Matthias Kaehlcke <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Diffstat (limited to 'include/linux/compiler-gcc.h')
| -rw-r--r-- | include/linux/compiler-gcc.h | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 7deaae3dc87d..cd4bbe8242bd 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)) |