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([134.208.63.146]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-835158312c5sm5247062b3a.8.2026.05.02.00.56.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 02 May 2026 00:56:19 -0700 (PDT) From: Qian-Yu Lin To: rostedt@goodmis.org Cc: mhiramat@kernel.org, david.laight.linux@gmail.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Qian-Yu Lin Subject: [PATCH v3] trace_printk: remove local variable for argument detection Date: Sat, 2 May 2026 15:55:34 +0800 Message-ID: <20260502075535.34997-1-tiffany019230@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260429165707.7020-1-tiffany019230@gmail.com> References: <20260429165707.7020-1-tiffany019230@gmail.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The trace_printk() macro uses a local variable _______STR to detect whether variadic arguments are present. This name can shadow outer variables. Replace the local variable with sizeof applied directly to the stringified arguments: if (sizeof __stringify((__VA_ARGS__)) > 3) This eliminates the shadowing risk entirely without introducing any additional includes or local variables. Verified with objdump on samples/trace_printk that all four cases branch correctly: __trace_bputs, __trace_puts, __trace_bprintk, and __trace_printk. Suggested-by: David Laight Signed-off-by: Qian-Yu Lin --- include/linux/trace_printk.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/include/linux/trace_printk.h b/include/linux/trace_printk.h index 2670ec7f4262..3d54f440dccf 100644 --- a/include/linux/trace_printk.h +++ b/include/linux/trace_printk.h @@ -86,8 +86,7 @@ do { \ #define trace_printk(fmt, ...) \ do { \ - char _______STR[] = __stringify((__VA_ARGS__)); \ - if (sizeof(_______STR) > 3) \ + if (sizeof __stringify((__VA_ARGS__)) > 3) \ do_trace_printk(fmt, ##__VA_ARGS__); \ else \ trace_puts(fmt); \ -- 2.43.0