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[98.38.17.99]) by smtp.googlemail.com with ESMTPSA id 8926c6da1cb9f-5aea7ce584bsm1212138173.27.2025.10.25.14.15.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 25 Oct 2025 14:15:30 -0700 (PDT) From: Jim Cromie To: linux-kernel@vger.kernel.org Cc: akpm@linuxfoundation.org, Jim Cromie , Luc Van Oostenryck , 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 Message-ID: <20251025211519.1616439-4-jim.cromie@gmail.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251025211519.1616439-1-jim.cromie@gmail.com> References: <20251025211519.1616439-1-jim.cromie@gmail.com> Precedence: bulk X-Mailing-List: linux-sparse@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- 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 #endif /* __LINUX_COMPILER_H */ -- 2.51.0