linux-kernel - [PATCH AUTOSEL 6.12 18/29] ARC: build: Use __force to suppress per-CPU cmpxchg warnings

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Message-Id: <20241220171130.511389-18-sashal@kernel.org>
Date: Fri, 20 Dec 2024 12:11:19 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: "Paul E. McKenney" <paulmck@...nel.org>,
	kernel test robot <lkp@...el.com>,
	linux-snps-arc@...ts.infradead.org,
	Vineet Gupta <vgupta@...nel.org>,
	Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 6.12 18/29] ARC: build: Use __force to suppress per-CPU cmpxchg warnings

From: "Paul E. McKenney" <paulmck@...nel.org>

[ Upstream commit 1e8af9f04346ecc0bccf0c53b728fc8eb3490a28 ]

Currently, the cast of the first argument to cmpxchg_emu_u8() drops the
__percpu address-space designator, which results in sparse complaints
when applying cmpxchg() to per-CPU variables in ARC.  Therefore, use
__force to suppress these complaints, given that this does not pertain
to cmpxchg() semantics, which are plently well-defined on variables in
general, whether per-CPU or otherwise.

Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202409251336.ToC0TvWB-lkp@intel.com/
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
Cc: <linux-snps-arc@...ts.infradead.org>
Signed-off-by: Vineet Gupta <vgupta@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arc/include/asm/cmpxchg.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h
index 58045c898340..76f43db0890f 100644
--- a/arch/arc/include/asm/cmpxchg.h
+++ b/arch/arc/include/asm/cmpxchg.h
@@ -48,7 +48,7 @@
 									\
 	switch(sizeof((_p_))) {						\
 	case 1:								\
-		_prev_ = (__typeof__(*(ptr)))cmpxchg_emu_u8((volatile u8 *)_p_, (uintptr_t)_o_, (uintptr_t)_n_);	\
+		_prev_ = (__typeof__(*(ptr)))cmpxchg_emu_u8((volatile u8 *__force)_p_, (uintptr_t)_o_, (uintptr_t)_n_);	\
 		break;							\
 	case 4:								\
 		_prev_ = __cmpxchg(_p_, _o_, _n_);			\
-- 
2.39.5