linux-kernel - [PATCH 3/3] Move IS_CONFIG

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Message-Id: <20210929181632.1489847-4-lucas.demarchi@intel.com>
Date:   Wed, 29 Sep 2021 11:16:32 -0700
From:   Lucas De Marchi <lucas.demarchi@...el.com>
To:     gfx-internal-devel@...ists.intel.com
Cc:     Daniel Vetter <daniel.vetter@...el.com>,
        dri-devel@...ts.freedesktop.org,
        Masahiro Yamada <masahiroy@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] Move IS_CONFIG_NONZERO() to kconfig.h

The check for config value doesn't really belong to i915_utils.h - we
are trying to eliminate that utils helper and share them when possible
with other drivers and subsystems.

Rationale for having such macro is in commit
babaab2f4738 ("drm/i915: Encapsulate kconfig constant values inside boolean predicates")
whereas later it is improved to not break the build if used with
undefined configs. The caveat is detailed in the documentation: unlike
IS_ENABLED(): it's not preprocessor-only logic so can't be used for
things like `#if IS_CONFIG_NONZERO(...)`

Signed-off-by: Lucas De Marchi <lucas.demarchi@...el.com>
---
 drivers/gpu/drm/i915/i915_utils.h | 17 -----------------
 include/linux/kconfig.h           | 16 ++++++++++++++--
 2 files changed, 14 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
index 436ce612c46a..62f189e064a9 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -28,7 +28,6 @@
 #include <linux/list.h>
 #include <linux/overflow.h>
 #include <linux/sched.h>
-#include <linux/stringify.h>
 #include <linux/types.h>
 #include <linux/workqueue.h>
 
@@ -459,20 +458,4 @@ static inline bool timer_expired(const struct timer_list *t)
 	return timer_active(t) && !timer_pending(t);
 }
 
-/*
- * This is a lookalike for IS_ENABLED() that takes a kconfig value,
- * e.g. CONFIG_DRM_I915_SPIN_REQUEST, and evaluates whether it is non-zero
- * i.e. whether the configuration is active. Wrapping up the config inside
- * a boolean context prevents clang and smatch from complaining about potential
- * issues in confusing logical-&& with bitwise-& for constants.
- *
- * Sadly IS_ENABLED() itself does not work with kconfig values.
- *
- * Returns 0 if @config is 0, 1 if set to any value.
- */
-#define IS_CONFIG_NONZERO(config) (						\
-	(__stringify_1(config)[0] > '0' && __stringify_1(config)[0] < '9') ||	\
-	__stringify_1(config)[0] == '-'						\
-)
-
 #endif /* !__I915_UTILS_H */
diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h
index 20d1079e92b4..e84f7c1c8e26 100644
--- a/include/linux/kconfig.h
+++ b/include/linux/kconfig.h
@@ -2,6 +2,7 @@
 #ifndef __LINUX_KCONFIG_H
 #define __LINUX_KCONFIG_H
 
+#include <linux/stringify.h>
 #include <generated/autoconf.h>
 
 #ifdef CONFIG_CPU_BIG_ENDIAN
@@ -26,8 +27,8 @@
 #define ____or(arg1_or_junk, y)		__take_second_arg(arg1_or_junk 1, y)
 
 /*
- * Helper macros to use CONFIG_ options in C/CPP expressions. Note that
- * these only work with boolean and tristate options.
+ * Helper macros to use CONFIG_ options in C/CPP expressions. Note that except
+ * for IS_CONFIG_NONZERO, these only work with boolean and tristate options.
  */
 
 /*
@@ -72,4 +73,15 @@
  */
 #define IS_ENABLED(option) __or(IS_BUILTIN(option), IS_MODULE(option))
 
+/*
+ * This is a lookalike for IS_ENABLED(), but works with int kconfig options
+ * with the caveat that it can't be used on preprocessor checks.
+ *
+ * Returns 0 if @config is 0 or undefined, 1 if set to any value.
+ */
+#define IS_CONFIG_NONZERO(config) (						\
+	(__stringify_1(config)[0] > '0' && __stringify_1(config)[0] < '9') ||	\
+	__stringify_1(config)[0] == '-'						\
+)
+
 #endif /* __LINUX_KCONFIG_H */
-- 
2.33.0