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| author |   David Rientjes <rientjes@google.com> | 2017-07-06 15:35:24 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-06 16:24:29 -0700 |
| commit | 9a04dbcfb33b4012d0ce8c0282f1e3ca694675b1 (patch) | |
| tree | ec802cb076b875d2e8259de087d8cd186cfce70f /include/linux/compiler-gcc.h | |
| parent | Merge branch 'for-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup (diff) | |
| download | linux-dev-9a04dbcfb33b4012d0ce8c0282f1e3ca694675b1.tar.xz linux-dev-9a04dbcfb33b4012d0ce8c0282f1e3ca694675b1.zip | |
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/alpine.DEB.2.10.1706261552200.1075@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: Sodagudi Prasad <psodagud@codeaurora.org>
Tested-by: Sodagudi Prasad <psodagud@codeaurora.org>
Tested-by: Matthias Kaehlcke <mka@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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)) |