linux-kernel - [PATCH v2] compiler.h: simplify data

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Message-ID: <fb62163f-ba21-4661-be5b-bb5124abc87d@p183>
Date: Mon, 24 Jun 2024 18:39:49 +0300
From: Alexey Dobriyan <adobriyan@...il.com>
To: Marco Elver <elver@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org
Subject: [PATCH v2] compiler.h: simplify data_race() macro

-Wdeclaration-after-statement used since forever required statement
expressions to inject __kcsan_disable_current(), __kcsan_enable_current()
to mark data race. Now that it is gone, make macro expansion simpler.

__unqual_scalar_typeof() is wordy macro by itself.
"expr" is expanded twice.

Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---

 include/linux/compiler.h |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -200,10 +200,8 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
  */
 #define data_race(expr)							\
 ({									\
-	__unqual_scalar_typeof(({ expr; })) __v = ({			\
-		__kcsan_disable_current();				\
-		expr;							\
-	});								\
+	__kcsan_disable_current();					\
+	__auto_type __v = (expr);					\
 	__kcsan_enable_current();					\
 	__v;								\
 })