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Subject[PATCH] arm64: fix unreachable code issue with cmpxchg
Date
On arm64 build with clang, sometimes the __cmpxchg_mb is not inlined
when CONFIG_OPTIMIZE_INLINING is set.
Clang then fails a compile-time assertion, because it cannot tell at
compile time what the size of the argument is:

mm/memcontrol.o: In function `__cmpxchg_mb':
memcontrol.c:(.text+0x1a4c): undefined reference to `__compiletime_assert_175'
memcontrol.c:(.text+0x1a4c): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `__compiletime_assert_175'

Mark all of the cmpxchg() style functions as __always_inline to
ensure that the compiler can see the result.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
arch/arm64/include/asm/cmpxchg.h | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/cmpxchg.h b/arch/arm64/include/asm/cmpxchg.h
index a1398f2f9994..fd64dc8a235f 100644
--- a/arch/arm64/include/asm/cmpxchg.h
+++ b/arch/arm64/include/asm/cmpxchg.h
@@ -19,7 +19,7 @@
* acquire+release for the latter.
*/
#define __XCHG_CASE(w, sfx, name, sz, mb, nop_lse, acq, acq_lse, rel, cl) \
-static inline u##sz __xchg_case_##name##sz(u##sz x, volatile void *ptr) \
+static __always_inline u##sz __xchg_case_##name##sz(u##sz x, volatile void *ptr)\
{ \
u##sz ret; \
unsigned long tmp; \
@@ -62,7 +62,7 @@ __XCHG_CASE( , , mb_, 64, dmb ish, nop, , a, l, "memory")
#undef __XCHG_CASE

#define __XCHG_GEN(sfx) \
-static inline unsigned long __xchg##sfx(unsigned long x, \
+static __always_inline unsigned long __xchg##sfx(unsigned long x, \
volatile void *ptr, \
int size) \
{ \
@@ -103,8 +103,9 @@ __XCHG_GEN(_mb)
#define arch_xchg_release(...) __xchg_wrapper(_rel, __VA_ARGS__)
#define arch_xchg(...) __xchg_wrapper( _mb, __VA_ARGS__)

-#define __CMPXCHG_CASE(name, sz) \
-static inline u##sz __cmpxchg_case_##name##sz(volatile void *ptr, \
+#define __CMPXCHG_CASE(name, sz) \
+static __always_inline u##sz \
+__cmpxchg_case_##name##sz(volatile void *ptr, \
u##sz old, \
u##sz new) \
{ \
@@ -148,7 +149,7 @@ __CMPXCHG_DBL(_mb)
#undef __CMPXCHG_DBL

#define __CMPXCHG_GEN(sfx) \
-static inline unsigned long __cmpxchg##sfx(volatile void *ptr, \
+static __always_inline unsigned long __cmpxchg##sfx(volatile void *ptr, \
unsigned long old, \
unsigned long new, \
int size) \
@@ -230,7 +231,7 @@ __CMPXCHG_GEN(_mb)
})

#define __CMPWAIT_CASE(w, sfx, sz) \
-static inline void __cmpwait_case_##sz(volatile void *ptr, \
+static __always_inline void __cmpwait_case_##sz(volatile void *ptr, \
unsigned long val) \
{ \
unsigned long tmp; \
@@ -255,7 +256,7 @@ __CMPWAIT_CASE( , , 64);
#undef __CMPWAIT_CASE

#define __CMPWAIT_GEN(sfx) \
-static inline void __cmpwait##sfx(volatile void *ptr, \
+static __always_inline void __cmpwait##sfx(volatile void *ptr, \
unsigned long val, \
int size) \
{ \
--
2.20.0
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