Re: [Intel-gfx] [PATCH v2 3/3] Move IS_CONFIG_NONZERO() to kconfig.h
On Fri, Oct 1, 2021 at 12:55 AM Lucas De Marchi
wrote:
>
> On Thu, Sep 30, 2021 at 11:01:36PM +0900, Masahiro Yamada wrote:
> >On Thu, Sep 30, 2021 at 3:34 AM Lucas De Marchi
> > wrote:
> >>
> >> 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
> >
> >
> >Hypothetical "it would be nice to have ..." is really unneeded.
> >
> > if (context && CONFIG_DRM_I915_FENCE_TIMEOUT > 0)
> > return
> >msecs_to_jiffies_timeout(CONFIG_DRM_I915_FENCE_TIMEOUT);
> >
> >
> >is enough, and much cleaner.
> >
> >
> >
> >This warning is shown only when a constant is used
> >together with '&&'.
> >
> >Most of IS_ACTIVE can go away.
> >
> >Given that, there are not many places where the IS_ACTIVE macro
> >is useful, even in the i915 driver.
> >
> >For a few sources of the warnings,
> >replacing it with != 0 or > 0 is just fine.
>
> humn... maybe. Let me do a conversion in that direction and see what is
> the outcome.
>
> My original intention was to make IS_ENABLED() even uglier to cover the
> int case, but after some tries it seems impossible to do on preprocessor
> context, so I thought maybe it would be ok as a separate one.
>
> >
> >Of course, such an ugly macro is not worth being moved to
>
> if we don't handle the undefined case and only worry about encapsulating
> it inside a boolean predicate, the macro would be very simple. Would
> that be worth having in kconfig.h maybe?
I do not think so.
#define IS_CONFIG_NONZERO(config) ((config) != 0)
seems like a stupid macro.
What is bad about writing the direct code?
if (x && CONFIG_FOO > 0)
>
>
> thanks
> Lucas De Marchi
--
Best Regards
Masahiro Yamada
Re: [Intel-gfx] [PATCH v2 3/3] Move IS_CONFIG_NONZERO() to kconfig.h
On Thu, Sep 30, 2021 at 11:01:36PM +0900, Masahiro Yamada wrote:
On Thu, Sep 30, 2021 at 3:34 AM Lucas De Marchi
wrote:
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
Hypothetical "it would be nice to have ..." is really unneeded.
if (context && CONFIG_DRM_I915_FENCE_TIMEOUT > 0)
return
msecs_to_jiffies_timeout(CONFIG_DRM_I915_FENCE_TIMEOUT);
is enough, and much cleaner.
This warning is shown only when a constant is used
together with '&&'.
Most of IS_ACTIVE can go away.
Given that, there are not many places where the IS_ACTIVE macro
is useful, even in the i915 driver.
For a few sources of the warnings,
replacing it with != 0 or > 0 is just fine.
humn... maybe. Let me do a conversion in that direction and see what is
the outcome.
My original intention was to make IS_ENABLED() even uglier to cover the
int case, but after some tries it seems impossible to do on preprocessor
context, so I thought maybe it would be ok as a separate one.
Of course, such an ugly macro is not worth being moved to
if we don't handle the undefined case and only worry about encapsulating
it inside a boolean predicate, the macro would be very simple. Would
that be worth having in kconfig.h maybe?
thanks
Lucas De Marchi
Re: [Intel-gfx] [PATCH v2 3/3] Move IS_CONFIG_NONZERO() to kconfig.h
On Thu, Sep 30, 2021 at 3:34 AM Lucas De Marchi
wrote:
>
> 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
Hypothetical "it would be nice to have ..." is really unneeded.
if (context && CONFIG_DRM_I915_FENCE_TIMEOUT > 0)
return
msecs_to_jiffies_timeout(CONFIG_DRM_I915_FENCE_TIMEOUT);
is enough, and much cleaner.
This warning is shown only when a constant is used
together with '&&'.
Most of IS_ACTIVE can go away.
Given that, there are not many places where the IS_ACTIVE macro
is useful, even in the i915 driver.
For a few sources of the warnings,
replacing it with != 0 or > 0 is just fine.
Of course, such an ugly macro is not worth being moved to
--
Best Regards
Masahiro Yamada
[Intel-gfx] [PATCH v2 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
---
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
#include
#include
-#include
#include
#include
@@ -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
#include
#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
