linux-kernel - [PATCH] LoongArch: Mark __xchg() and __cmpxchg() as __always

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Date:   Mon, 10 Oct 2022 19:56:20 +0800
From:   Huacai Chen <chenhuacai@...ngson.cn>
To:     Arnd Bergmann <arnd@...db.de>, Huacai Chen <chenhuacai@...nel.org>
Cc:     loongarch@...ts.linux.dev, linux-arch@...r.kernel.org,
        Xuefeng Li <lixuefeng@...ngson.cn>,
        Guo Ren <guoren@...nel.org>, Xuerui Wang <kernel@...0n.name>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        linux-kernel@...r.kernel.org, Huacai Chen <chenhuacai@...ngson.cn>
Subject: [PATCH] LoongArch: Mark __xchg() and __cmpxchg() as __always_inline

Commit ac7c3e4ff401 ("compiler: enable CONFIG_OPTIMIZE_INLINING
forcibly") allows compiler to uninline functions marked as 'inline'.
In case of __xchg()/__cmpxchg() this would cause to reference
BUILD_BUG(), which is an error case for catching bugs and will not
happen for correct code, if __xchg()/__cmpxchg() is inlined.

This bug can be produced with CONFIG_DEBUG_SECTION_MISMATCH enabled,
and the solution is similar to below commits:
46f1619500d0225 ("MIPS: include: Mark __xchg as __always_inline"),
88356d09904bc60 ("MIPS: include: Mark __cmpxchg as __always_inline").

Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
---
 arch/loongarch/include/asm/cmpxchg.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/loongarch/include/asm/cmpxchg.h b/arch/loongarch/include/asm/cmpxchg.h
index ae19e33c7754..ecfa6cf79806 100644
--- a/arch/loongarch/include/asm/cmpxchg.h
+++ b/arch/loongarch/include/asm/cmpxchg.h
@@ -61,8 +61,8 @@ static inline unsigned int __xchg_small(volatile void *ptr, unsigned int val,
 	return (old32 & mask) >> shift;
 }
 
-static inline unsigned long __xchg(volatile void *ptr, unsigned long x,
-				   int size)
+static __always_inline unsigned long
+__xchg(volatile void *ptr, unsigned long x, int size)
 {
 	switch (size) {
 	case 1:
@@ -159,8 +159,8 @@ static inline unsigned int __cmpxchg_small(volatile void *ptr, unsigned int old,
 	return (old32 & mask) >> shift;
 }
 
-static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
-				      unsigned long new, unsigned int size)
+static __always_inline unsigned long
+__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, unsigned int size)
 {
 	switch (size) {
 	case 1:
-- 
2.31.1