linux-kernel - [PATCH] compiler_attribute: remove CONFIG_ENABLE_MUST

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Date:   Sun, 22 Nov 2020 04:43:39 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
Cc:     Masahiro Yamada <masahiroy@...nel.org>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Shuah Khan <shuah@...nel.org>, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, netdev@...r.kernel.org,
        wireguard@...ts.zx2c4.com
Subject: [PATCH] compiler_attribute: remove CONFIG_ENABLE_MUST_CHECK

Revert commit cebc04ba9aeb ("add CONFIG_ENABLE_MUST_CHECK").

A lot of warn_unused_result warnings existed in 2006, but until now
they have been fixed thanks to people doing allmodconfig tests.

Our goal is to always enable __must_check where appreciate, so this
CONFIG option is no longer needed.

I see a lot of defconfig (arch/*/configs/*_defconfig) files having:

    # CONFIG_ENABLE_MUST_CHECK is not set

I did not touch them for now since it would be a big churn. If arch
maintainers want to clean them up, please go ahead.

Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
---

 include/linux/compiler_types.h                      | 4 ----
 lib/Kconfig.debug                                   | 8 --------
 tools/testing/selftests/wireguard/qemu/debug.config | 1 -
 3 files changed, 13 deletions(-)

diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index ac3fa37a84f9..02f6d3fbad9d 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -110,11 +110,7 @@ struct ftrace_likely_data {
 	unsigned long			constant;
 };
 
-#ifdef CONFIG_ENABLE_MUST_CHECK
 #define __must_check		__attribute__((__warn_unused_result__))
-#else
-#define __must_check
-#endif
 
 #if defined(CC_USING_HOTPATCH)
 #define notrace			__attribute__((hotpatch(0, 0)))
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index c789b39ed527..cb8ef4fd0d02 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -286,14 +286,6 @@ config GDB_SCRIPTS
 
 endif # DEBUG_INFO
 
-config ENABLE_MUST_CHECK
-	bool "Enable __must_check logic"
-	default y
-	help
-	  Enable the __must_check logic in the kernel build.  Disable this to
-	  suppress the "warning: ignoring return value of 'foo', declared with
-	  attribute warn_unused_result" messages.
-
 config FRAME_WARN
 	int "Warn for stack frames larger than"
 	range 0 8192
diff --git a/tools/testing/selftests/wireguard/qemu/debug.config b/tools/testing/selftests/wireguard/qemu/debug.config
index b50c2085c1ac..fe07d97df9fa 100644
--- a/tools/testing/selftests/wireguard/qemu/debug.config
+++ b/tools/testing/selftests/wireguard/qemu/debug.config
@@ -1,5 +1,4 @@
 CONFIG_LOCALVERSION="-debug"
-CONFIG_ENABLE_MUST_CHECK=y
 CONFIG_FRAME_POINTER=y
 CONFIG_STACK_VALIDATION=y
 CONFIG_DEBUG_KERNEL=y
-- 
2.25.1