linux-kernel - [PATCH v2 09/10] asm-generic: percpu: Add assembly guard

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Message-Id: <20250810055136.897712-10-tiwei.bie@linux.dev>
Date: Sun, 10 Aug 2025 13:51:35 +0800
From: Tiwei Bie <tiwei.bie@...ux.dev>
To: richard@....at,
	anton.ivanov@...bridgegreys.com,
	johannes@...solutions.net
Cc: linux-um@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	benjamin@...solutions.net,
	arnd@...db.de,
	tiwei.btw@...group.com,
	tiwei.bie@...ux.dev,
	linux-arch@...r.kernel.org
Subject: [PATCH v2 09/10] asm-generic: percpu: Add assembly guard

From: Tiwei Bie <tiwei.btw@...group.com>

Currently, asm/percpu.h is directly or indirectly included by
some assembly files on x86. Some of them (e.g., checksum_32.S)
are also used on um. But x86 and um provide different versions
of asm/percpu.h -- um uses asm-generic/percpu.h directly.

When SMP is enabled, asm-generic/percpu.h will introduce C code
that cannot be assembled. Since asm-generic/percpu.h currently
is not designed for use in assembly, and these assembly files
do not actually need asm/percpu.h on um, let's add the assembly
guard in asm-generic/percpu.h to fix this issue.

Cc: Arnd Bergmann <arnd@...db.de>
Cc: linux-arch@...r.kernel.org
Signed-off-by: Tiwei Bie <tiwei.btw@...group.com>
---
 include/asm-generic/percpu.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h
index 02aeca21479a..6628670bcb90 100644
--- a/include/asm-generic/percpu.h
+++ b/include/asm-generic/percpu.h
@@ -2,6 +2,8 @@
 #ifndef _ASM_GENERIC_PERCPU_H_
 #define _ASM_GENERIC_PERCPU_H_

+#ifndef __ASSEMBLER__
+
 #include <linux/compiler.h>
 #include <linux/threads.h>
 #include <linux/percpu-defs.h>
@@ -557,4 +559,5 @@ do {									\
 	this_cpu_generic_cmpxchg(pcp, oval, nval)
 #endif

+#endif /* __ASSEMBLER__ */
 #endif /* _ASM_GENERIC_PERCPU_H_ */
-- 
2.34.1