[PATCH v3 1/2] drm: enable (most) W=1 warnings by default across the subsystem

[Danilo Krummrich]

On 2/1/24 15:33, Jani Nikula wrote:
> At least the i915 and amd drivers enable a bunch more compiler warnings
> than the kernel defaults.
> 
> Extend most of the W=1 warnings to the entire drm subsystem by
> default. Use the copy-pasted warnings from scripts/Makefile.extrawarn
> with s/KBUILD_CFLAGS/subdir-ccflags-y/ to make it easier to compare and
> keep up with them in the future.
> 
> This is similar to the approach currently used in i915.
> 
> Some of the -Wextra warnings do need to be disabled, just like in
> Makefile.extrawarn, but take care to not disable them for W=2 or W=3
> builds, depending on the warning.
> 
> There are too many -Wformat-truncation warnings to cleanly fix up front;
> leave that warning disabled for now.
> 
> v3:
> - Drop -Wmissing-declarations (already enabled by default)
> - Drop -Wmissing-prototypes (already enabled by default)
> 
> v2:
> - Drop -Wformat-truncation (too many warnings)
> - Drop -Wstringop-overflow (already enabled by default)
> 
> Cc: David Airlie <airlied at gmail.com>
> Cc: Daniel Vetter <daniel at ffwll.ch>
> Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Cc: Maxime Ripard <mripard at kernel.org>
> Cc: Thomas Zimmermann <tzimmermann at suse.de>
> Cc: Alex Deucher <alexander.deucher at amd.com>
> Cc: Christian König <christian.koenig at amd.com>
> Cc: Pan, Xinhui <Xinhui.Pan at amd.com>
> Cc: Karol Herbst <kherbst at redhat.com>
> Cc: Lyude Paul <lyude at redhat.com>
> Cc: Danilo Krummrich <dakr at redhat.com>
> Cc: Rob Clark <robdclark at gmail.com>
> Cc: Abhinav Kumar <quic_abhinavk at quicinc.com>
> Cc: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> Cc: Sean Paul <sean at poorly.run>
> Cc: Marijn Suijten <marijn.suijten at somainline.org>
> Cc: Hamza Mahfooz <hamza.mahfooz at amd.com>
> Acked-by: Javier Martinez Canillas <javierm at redhat.com>
> Acked-by: Thomas Zimmermann <tzimmermann at suse.de>
> Acked-by: Sui Jingfeng <sui.jingfeng at linux.dev>
> Signed-off-by: Jani Nikula <jani.nikula at intel.com>

Acked-by: Danilo Krummrich <dakr at redhat.com>

> ---
>   drivers/gpu/drm/Makefile | 25 +++++++++++++++++++++++++
>   1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index 104b42df2e95..04722a5dfb78 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -5,6 +5,31 @@
>   
>   CFLAGS-$(CONFIG_DRM_USE_DYNAMIC_DEBUG)	+= -DDYNAMIC_DEBUG_MODULE
>   
> +# Unconditionally enable W=1 warnings locally
> +# --- begin copy-paste W=1 warnings from scripts/Makefile.extrawarn
> +subdir-ccflags-y += -Wextra -Wunused -Wno-unused-parameter
> +subdir-ccflags-y += $(call cc-option, -Wrestrict)
> +subdir-ccflags-y += -Wmissing-format-attribute
> +subdir-ccflags-y += -Wold-style-definition
> +subdir-ccflags-y += -Wmissing-include-dirs
> +subdir-ccflags-y += $(call cc-option, -Wunused-but-set-variable)
> +subdir-ccflags-y += $(call cc-option, -Wunused-const-variable)
> +subdir-ccflags-y += $(call cc-option, -Wpacked-not-aligned)
> +subdir-ccflags-y += $(call cc-option, -Wformat-overflow)
> +# FIXME: fix -Wformat-truncation warnings and uncomment
> +#subdir-ccflags-y += $(call cc-option, -Wformat-truncation)
> +subdir-ccflags-y += $(call cc-option, -Wstringop-truncation)
> +# The following turn off the warnings enabled by -Wextra
> +ifeq ($(findstring 2, $(KBUILD_EXTRA_WARN)),)
> +subdir-ccflags-y += -Wno-missing-field-initializers
> +subdir-ccflags-y += -Wno-type-limits
> +subdir-ccflags-y += -Wno-shift-negative-value
> +endif
> +ifeq ($(findstring 3, $(KBUILD_EXTRA_WARN)),)
> +subdir-ccflags-y += -Wno-sign-compare
> +endif
> +# --- end copy-paste
> +
>   drm-y := \
>   	drm_aperture.o \
>   	drm_atomic.o \