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-rw-r--r--include/linux/compiler-gcc.h29
1 files changed, 22 insertions, 7 deletions
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index f43113b8890b..c11032b06d68 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -66,25 +66,40 @@
#endif
/*
+ * Feature detection for gnu_inline (gnu89 extern inline semantics). Either
+ * __GNUC_STDC_INLINE__ is defined (not using gnu89 extern inline semantics,
+ * and we opt in to the gnu89 semantics), or __GNUC_STDC_INLINE__ is not
+ * defined so the gnu89 semantics are the default.
+ */
+#ifdef __GNUC_STDC_INLINE__
+# define __gnu_inline __attribute__((gnu_inline))
+#else
+# define __gnu_inline
+#endif
+
+/*
* Force always-inline if the user requests it so via the .config,
* 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.
+ * Prefer gnu_inline, so that extern inline functions do not emit an
+ * externally visible function. This makes extern inline behave as per gnu89
+ * semantics rather than c99. This prevents multiple symbol definition errors
+ * of extern inline functions at link time.
+ * A lot of inline functions can cause havoc with function tracing.
*/
#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
!defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
-#define inline inline __attribute__((always_inline,unused)) 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 __gnu_inline
#else
-/* A lot of inline functions can cause havoc with function tracing */
-#define inline inline __attribute__((unused)) notrace
-#define __inline__ __inline__ __attribute__((unused)) notrace
-#define __inline __inline __attribute__((unused)) notrace
+#define inline inline __attribute__((unused)) notrace __gnu_inline
#endif
+#define __inline__ inline
+#define __inline inline
#define __always_inline inline __attribute__((always_inline))
#define noinline __attribute__((noinline))