From: Jim Cromie <jim.cromie@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: akpm@linuxfoundation.org, Jim Cromie <jim.cromie@gmail.com>,
Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
linux-sparse@vger.kernel.org (open list:SPARSE CHECKER)
Subject: [PATCH 3/3] compiler.h: add __chkp_no_side_effects() empty hint/assertion macro
Date: Sat, 25 Oct 2025 15:15:18 -0600 [thread overview]
Message-ID: <20251025211519.1616439-4-jim.cromie@gmail.com> (raw)
In-Reply-To: <20251025211519.1616439-1-jim.cromie@gmail.com>
cpp has no intrinsic protection against macro arg side-effects, so to
compensate, checkpatch is paranoid:
CHECK: Macro argument reuse '_var' - possible side-effects?
Allow an author to suppress these warnings on _var by adding
'__chkp_no_side_effects(_var)' to the body of macros which trigger
that warning. This may reduce blowouts in CI pipelines.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
include/linux/compiler.h | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 64ff73c533e5..96f6bfbd4088 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -379,6 +379,18 @@ static inline void *offset_to_ptr(const int *off)
*/
#define prevent_tail_call_optimization() mb()
+/*
+ * tell checkpatch --strict that you know the named args (a subset of
+ * the containing macro's args) are safe for multiple expansions.
+ *
+ * Prefer ({ typeof ..}) or do{}while(0) when they work. They would
+ * not work on module_param_named(name, value, type, perm), or on a
+ * locally useful "for_simplicity()" macro.
+ *
+ * NB: use at top of macro body, omit trailing semicolon.
+ */
+#define __chkp_no_side_effects(...) /* checkpatch "annotation" helper */
+
#include <asm/rwonce.h>
#endif /* __LINUX_COMPILER_H */
--
2.51.0
next parent reply other threads:[~2025-10-25 21:15 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20251025211519.1616439-1-jim.cromie@gmail.com>
2025-10-25 21:15 ` Jim Cromie [this message]
2025-10-26 0:09 ` [PATCH 3/3] compiler.h: add __chkp_no_side_effects() empty hint/assertion macro Linus Torvalds
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