From: Nathan Chancellor <natechancellor@xxxxxxxxx> [ Upstream commit b5bb425871186303e6936fa2581521bdd1964a58 ] Clang warns that if the default case is taken, ret will be uninitialized. ./arch/arm64/include/asm/percpu.h:196:2: warning: variable 'ret' is used uninitialized whenever switch default is taken [-Wsometimes-uninitialized] default: ^~~~~~~ ./arch/arm64/include/asm/percpu.h:200:9: note: uninitialized use occurs here return ret; ^~~ ./arch/arm64/include/asm/percpu.h:157:19: note: initialize the variable 'ret' to silence this warning unsigned long ret, loop; ^ = 0 This warning appears several times while building the erofs filesystem. While it's not strictly wrong, the BUILD_BUG will prevent this from becoming a true problem. Initialize ret to 0 in the default case right before the BUILD_BUG to silence all of these warnings. Reported-by: Prasad Sodagudi <psodagud@xxxxxxxxxxxxxx> Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx> Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> Signed-off-by: Dennis Zhou <dennis@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- arch/arm64/include/asm/percpu.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h index 0d551576eb57..4724b8f0b625 100644 --- a/arch/arm64/include/asm/percpu.h +++ b/arch/arm64/include/asm/percpu.h @@ -92,6 +92,7 @@ static inline unsigned long __percpu_##op(void *ptr, \ : [val] "Ir" (val)); \ break; \ default: \ + ret = 0; \ BUILD_BUG(); \ } \ \ @@ -121,6 +122,7 @@ static inline unsigned long __percpu_read(void *ptr, int size) ret = ACCESS_ONCE(*(u64 *)ptr); break; default: + ret = 0; BUILD_BUG(); } @@ -190,6 +192,7 @@ static inline unsigned long __percpu_xchg(void *ptr, unsigned long val, : [val] "r" (val)); break; default: + ret = 0; BUILD_BUG(); } -- 2.17.1