| Message ID | 20231129181219.1237887-1-jani.nikula@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [RFC] drm: enable W=1 warnings by default across the subsystem | expand |
Cc: Nathan Chancellor <nathan@kernel.org> On 11/29/23 13:12, Jani Nikula wrote: > At least the i915 and amd drivers enable a bunch more compiler warnings > than the kernel defaults. > > Extend 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. I think this should go in after drm-misc-next has a clean build (for COMPILE_TEST builds) with this patch applied. Otherwise, it will break a lot of build configs. > > Cc: David Airlie <airlied@gmail.com> > Cc: Daniel Vetter <daniel@ffwll.ch> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> > Cc: Maxime Ripard <mripard@kernel.org> > Cc: Thomas Zimmermann <tzimmermann@suse.de> > Cc: Alex Deucher <alexander.deucher@amd.com> > Cc: Christian König <christian.koenig@amd.com> > Cc: Pan, Xinhui <Xinhui.Pan@amd.com> > Cc: Karol Herbst <kherbst@redhat.com> > Cc: Lyude Paul <lyude@redhat.com> > Cc: Danilo Krummrich <dakr@redhat.com> > Cc: Rob Clark <robdclark@gmail.com> > Cc: Abhinav Kumar <quic_abhinavk@quicinc.com> > Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> > Cc: Sean Paul <sean@poorly.run> > Cc: Marijn Suijten <marijn.suijten@somainline.org> > Signed-off-by: Jani Nikula <jani.nikula@intel.com> > > --- > > With my admittedly limited and very much x86 focused kernel config, I > get some -Wunused-but-set-variable and -Wformat-truncation= warnings, > but nothing we can't handle. > > We could fix them up front, or disable the extra warnings on a per > driver basis with a FIXME comment in their respective Makefiles. > > With the experience from i915, I think this would significantly reduce > the constant loop of warnings added by people not using W=1 and > subsequently fixed by people using W=1. > > Note: I've Cc'd the maintainers of drm, drm misc and some of the biggest > drivers. > --- > drivers/gpu/drm/Makefile | 27 +++++++++++++++++++++++++++ > 1 file changed, 27 insertions(+) > > diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile > index b4cb0835620a..6939e4ea13d5 100644 > --- a/drivers/gpu/drm/Makefile > +++ b/drivers/gpu/drm/Makefile > @@ -5,6 +5,33 @@ > > 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 += -Wmissing-declarations > +subdir-ccflags-y += $(call cc-option, -Wrestrict) > +subdir-ccflags-y += -Wmissing-format-attribute > +subdir-ccflags-y += -Wmissing-prototypes > +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) > +subdir-ccflags-y += $(call cc-option, -Wformat-truncation) > +subdir-ccflags-y += $(call cc-option, -Wstringop-overflow) > +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 \
On Wed, 29 Nov 2023, Hamza Mahfooz <hamza.mahfooz@amd.com> wrote: > Cc: Nathan Chancellor <nathan@kernel.org> > > On 11/29/23 13:12, Jani Nikula wrote: >> At least the i915 and amd drivers enable a bunch more compiler warnings >> than the kernel defaults. >> >> Extend 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. > > I think this should go in after drm-misc-next has a clean build (for > COMPILE_TEST builds) with this patch applied. Otherwise, it will break a > lot of build configs. Oh, I'm absolutely not suggesting this should be merged before known warnings have been addressed one way or another. Either by fixing them or by disabling said warning in driver local Makefiles, depending on the case. While I'm suggesting this, I obviously (I hope) can't take on fixing all the warnings this exposes. One way to scale would be for folks to apply this locally, see what it uncovers in their drivers, and fix some. As an intermediate step we might also apply this to a topic branch in drm-tip, so you'd see the warnings when building drm-tip, but not in indidual branches or in anything that's merged upstream. BR, Jani. > >> >> Cc: David Airlie <airlied@gmail.com> >> Cc: Daniel Vetter <daniel@ffwll.ch> >> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> >> Cc: Maxime Ripard <mripard@kernel.org> >> Cc: Thomas Zimmermann <tzimmermann@suse.de> >> Cc: Alex Deucher <alexander.deucher@amd.com> >> Cc: Christian König <christian.koenig@amd.com> >> Cc: Pan, Xinhui <Xinhui.Pan@amd.com> >> Cc: Karol Herbst <kherbst@redhat.com> >> Cc: Lyude Paul <lyude@redhat.com> >> Cc: Danilo Krummrich <dakr@redhat.com> >> Cc: Rob Clark <robdclark@gmail.com> >> Cc: Abhinav Kumar <quic_abhinavk@quicinc.com> >> Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> >> Cc: Sean Paul <sean@poorly.run> >> Cc: Marijn Suijten <marijn.suijten@somainline.org> >> Signed-off-by: Jani Nikula <jani.nikula@intel.com> >> >> --- >> >> With my admittedly limited and very much x86 focused kernel config, I >> get some -Wunused-but-set-variable and -Wformat-truncation= warnings, >> but nothing we can't handle. >> >> We could fix them up front, or disable the extra warnings on a per >> driver basis with a FIXME comment in their respective Makefiles. >> >> With the experience from i915, I think this would significantly reduce >> the constant loop of warnings added by people not using W=1 and >> subsequently fixed by people using W=1. >> >> Note: I've Cc'd the maintainers of drm, drm misc and some of the biggest >> drivers. >> --- >> drivers/gpu/drm/Makefile | 27 +++++++++++++++++++++++++++ >> 1 file changed, 27 insertions(+) >> >> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile >> index b4cb0835620a..6939e4ea13d5 100644 >> --- a/drivers/gpu/drm/Makefile >> +++ b/drivers/gpu/drm/Makefile >> @@ -5,6 +5,33 @@ >> >> 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 += -Wmissing-declarations >> +subdir-ccflags-y += $(call cc-option, -Wrestrict) >> +subdir-ccflags-y += -Wmissing-format-attribute >> +subdir-ccflags-y += -Wmissing-prototypes >> +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) >> +subdir-ccflags-y += $(call cc-option, -Wformat-truncation) >> +subdir-ccflags-y += $(call cc-option, -Wstringop-overflow) >> +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 \
Hi, On Thu, Nov 30, 2023 at 10:52:17AM +0200, Jani Nikula wrote: > On Wed, 29 Nov 2023, Hamza Mahfooz <hamza.mahfooz@amd.com> wrote: > > Cc: Nathan Chancellor <nathan@kernel.org> > > > > On 11/29/23 13:12, Jani Nikula wrote: > >> At least the i915 and amd drivers enable a bunch more compiler warnings > >> than the kernel defaults. > >> > >> Extend 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. > > > > I think this should go in after drm-misc-next has a clean build (for > > COMPILE_TEST builds) with this patch applied. Otherwise, it will break a > > lot of build configs. > > Oh, I'm absolutely not suggesting this should be merged before known > warnings have been addressed one way or another. Either by fixing them > or by disabling said warning in driver local Makefiles, depending on the > case. I'm all for it, but yeah, we need some easy way to opt-in/opt-out. Some drivers are pretty much unmaintained now and are likely to never fix those warnings. Maxime
Maxime Ripard <mripard@kernel.org> writes: > Hi, > > On Thu, Nov 30, 2023 at 10:52:17AM +0200, Jani Nikula wrote: >> On Wed, 29 Nov 2023, Hamza Mahfooz <hamza.mahfooz@amd.com> wrote: >> > Cc: Nathan Chancellor <nathan@kernel.org> >> > >> > On 11/29/23 13:12, Jani Nikula wrote: >> >> At least the i915 and amd drivers enable a bunch more compiler warnings >> >> than the kernel defaults. >> >> >> >> Extend 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. >> > >> > I think this should go in after drm-misc-next has a clean build (for >> > COMPILE_TEST builds) with this patch applied. Otherwise, it will break a >> > lot of build configs. >> >> Oh, I'm absolutely not suggesting this should be merged before known >> warnings have been addressed one way or another. Either by fixing them >> or by disabling said warning in driver local Makefiles, depending on the >> case. > > I'm all for it, but yeah, we need some easy way to opt-in/opt-out. Some > drivers are pretty much unmaintained now and are likely to never fix > those warnings. > Maybe add a Kconfig symbol for it instead of making unconditional? Something like: +# Unconditionally enable W=1 warnings locally +# --- begin copy-paste W=1 warnings from scripts/Makefile.extrawarn +subdir-ccflags-$(CONFIG_DRM_EXTRA_CHECKS) += -Wextra -Wunused -Wno-unused-parameter ... > Maxime
On Thu, 30 Nov 2023, Javier Martinez Canillas <javierm@redhat.com> wrote: > Maxime Ripard <mripard@kernel.org> writes: > >> Hi, >> >> On Thu, Nov 30, 2023 at 10:52:17AM +0200, Jani Nikula wrote: >>> On Wed, 29 Nov 2023, Hamza Mahfooz <hamza.mahfooz@amd.com> wrote: >>> > Cc: Nathan Chancellor <nathan@kernel.org> >>> > >>> > On 11/29/23 13:12, Jani Nikula wrote: >>> >> At least the i915 and amd drivers enable a bunch more compiler warnings >>> >> than the kernel defaults. >>> >> >>> >> Extend 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. >>> > >>> > I think this should go in after drm-misc-next has a clean build (for >>> > COMPILE_TEST builds) with this patch applied. Otherwise, it will break a >>> > lot of build configs. >>> >>> Oh, I'm absolutely not suggesting this should be merged before known >>> warnings have been addressed one way or another. Either by fixing them >>> or by disabling said warning in driver local Makefiles, depending on the >>> case. >> >> I'm all for it, but yeah, we need some easy way to opt-in/opt-out. Some >> drivers are pretty much unmaintained now and are likely to never fix >> those warnings. Then I'd go for enabling in drm level and disabling individual warnings in the driver Makefile level if they won't get fixed. > Maybe add a Kconfig symbol for it instead of making unconditional? > > Something like: > > +# Unconditionally enable W=1 warnings locally > +# --- begin copy-paste W=1 warnings from scripts/Makefile.extrawarn > +subdir-ccflags-$(CONFIG_DRM_EXTRA_CHECKS) += -Wextra -Wunused -Wno-unused-parameter > ... Then we'll have a ping pong of people not using W=1 or CONFIG_DRM_EXTRA_CHECKS introducing warnings, and people using them fixing the warnings... I really do think making it unconditional is the only way. BR, Jani.
Jani Nikula <jani.nikula@intel.com> writes: [...] > > Then I'd go for enabling in drm level and disabling individual warnings > in the driver Makefile level if they won't get fixed. > >> Maybe add a Kconfig symbol for it instead of making unconditional? >> >> Something like: >> >> +# Unconditionally enable W=1 warnings locally >> +# --- begin copy-paste W=1 warnings from scripts/Makefile.extrawarn >> +subdir-ccflags-$(CONFIG_DRM_EXTRA_CHECKS) += -Wextra -Wunused -Wno-unused-parameter >> ... > > Then we'll have a ping pong of people not using W=1 or > CONFIG_DRM_EXTRA_CHECKS introducing warnings, and people using them > fixing the warnings... > > I really do think making it unconditional is the only way. > Fair enough.
Am 29.11.23 um 19:12 schrieb Jani Nikula: > At least the i915 and amd drivers enable a bunch more compiler warnings > than the kernel defaults. > > Extend 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. > > Cc: David Airlie <airlied@gmail.com> > Cc: Daniel Vetter <daniel@ffwll.ch> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> > Cc: Maxime Ripard <mripard@kernel.org> > Cc: Thomas Zimmermann <tzimmermann@suse.de> > Cc: Alex Deucher <alexander.deucher@amd.com> > Cc: Christian König <christian.koenig@amd.com> > Cc: Pan, Xinhui <Xinhui.Pan@amd.com> > Cc: Karol Herbst <kherbst@redhat.com> > Cc: Lyude Paul <lyude@redhat.com> > Cc: Danilo Krummrich <dakr@redhat.com> > Cc: Rob Clark <robdclark@gmail.com> > Cc: Abhinav Kumar <quic_abhinavk@quicinc.com> > Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> > Cc: Sean Paul <sean@poorly.run> > Cc: Marijn Suijten <marijn.suijten@somainline.org> > Signed-off-by: Jani Nikula <jani.nikula@intel.com> Acked-by: Thomas Zimmermann <tzimmermann@suse.de> > > --- > > With my admittedly limited and very much x86 focused kernel config, I > get some -Wunused-but-set-variable and -Wformat-truncation= warnings, > but nothing we can't handle. > > We could fix them up front, or disable the extra warnings on a per > driver basis with a FIXME comment in their respective Makefiles. > > With the experience from i915, I think this would significantly reduce > the constant loop of warnings added by people not using W=1 and > subsequently fixed by people using W=1. > > Note: I've Cc'd the maintainers of drm, drm misc and some of the biggest > drivers. > --- > drivers/gpu/drm/Makefile | 27 +++++++++++++++++++++++++++ > 1 file changed, 27 insertions(+) > > diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile > index b4cb0835620a..6939e4ea13d5 100644 > --- a/drivers/gpu/drm/Makefile > +++ b/drivers/gpu/drm/Makefile > @@ -5,6 +5,33 @@ > > 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 += -Wmissing-declarations > +subdir-ccflags-y += $(call cc-option, -Wrestrict) > +subdir-ccflags-y += -Wmissing-format-attribute > +subdir-ccflags-y += -Wmissing-prototypes > +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) > +subdir-ccflags-y += $(call cc-option, -Wformat-truncation) > +subdir-ccflags-y += $(call cc-option, -Wstringop-overflow) > +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 \
On Thu, Nov 30, 2023 at 11:46:00AM +0200, Jani Nikula wrote: > On Thu, 30 Nov 2023, Javier Martinez Canillas <javierm@redhat.com> wrote: > > Maxime Ripard <mripard@kernel.org> writes: > > > >> Hi, > >> > >> On Thu, Nov 30, 2023 at 10:52:17AM +0200, Jani Nikula wrote: > >>> On Wed, 29 Nov 2023, Hamza Mahfooz <hamza.mahfooz@amd.com> wrote: > >>> > Cc: Nathan Chancellor <nathan@kernel.org> > >>> > > >>> > On 11/29/23 13:12, Jani Nikula wrote: > >>> >> At least the i915 and amd drivers enable a bunch more compiler warnings > >>> >> than the kernel defaults. > >>> >> > >>> >> Extend 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. > >>> > > >>> > I think this should go in after drm-misc-next has a clean build (for > >>> > COMPILE_TEST builds) with this patch applied. Otherwise, it will break a > >>> > lot of build configs. > >>> > >>> Oh, I'm absolutely not suggesting this should be merged before known > >>> warnings have been addressed one way or another. Either by fixing them > >>> or by disabling said warning in driver local Makefiles, depending on the > >>> case. > >> > >> I'm all for it, but yeah, we need some easy way to opt-in/opt-out. Some > >> drivers are pretty much unmaintained now and are likely to never fix > >> those warnings. > > Then I'd go for enabling in drm level and disabling individual warnings > in the driver Makefile level if they won't get fixed. > > > Maybe add a Kconfig symbol for it instead of making unconditional? > > > > Something like: > > > > +# Unconditionally enable W=1 warnings locally > > +# --- begin copy-paste W=1 warnings from scripts/Makefile.extrawarn > > +subdir-ccflags-$(CONFIG_DRM_EXTRA_CHECKS) += -Wextra -Wunused -Wno-unused-parameter > > ... > > Then we'll have a ping pong of people not using W=1 or > CONFIG_DRM_EXTRA_CHECKS introducing warnings, and people using them > fixing the warnings... > > I really do think making it unconditional is the only way. Yeah, I agree. Plus, if we need to have an extra Kconfig option, it's pretty equivalent to using W=1 Maxime
Maxime Ripard <mripard@kernel.org> writes: > On Thu, Nov 30, 2023 at 11:46:00AM +0200, Jani Nikula wrote: [...] >> >> Then we'll have a ping pong of people not using W=1 or >> CONFIG_DRM_EXTRA_CHECKS introducing warnings, and people using them >> fixing the warnings... >> >> I really do think making it unconditional is the only way. > > Yeah, I agree. > > Plus, if we need to have an extra Kconfig option, it's pretty equivalent > to using W=1 > Yeah, with the difference that having a Kconfig symbol allows for example distros to set it in their kernel configs. It's a fair point though that probably the only option is to enable it unconditionally. Acked-by: Javier Martinez Canillas <javierm@redhat.com>
On Thu, Nov 30, 2023 at 10:52:17AM +0200, Jani Nikula wrote: > On Wed, 29 Nov 2023, Hamza Mahfooz <hamza.mahfooz@amd.com> wrote: > > Cc: Nathan Chancellor <nathan@kernel.org> > > > > On 11/29/23 13:12, Jani Nikula wrote: > >> At least the i915 and amd drivers enable a bunch more compiler warnings > >> than the kernel defaults. > >> > >> Extend 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. > > > > I think this should go in after drm-misc-next has a clean build (for > > COMPILE_TEST builds) with this patch applied. Otherwise, it will break a > > lot of build configs. > > Oh, I'm absolutely not suggesting this should be merged before known > warnings have been addressed one way or another. Either by fixing them > or by disabling said warning in driver local Makefiles, depending on the > case. > > While I'm suggesting this, I obviously (I hope) can't take on fixing all > the warnings this exposes. One way to scale would be for folks to apply > this locally, see what it uncovers in their drivers, and fix some. > > As an intermediate step we might also apply this to a topic branch in > drm-tip, so you'd see the warnings when building drm-tip, but not in > indidual branches or in anything that's merged upstream. For what it's worth, I ran this through my personal build matrix with LLVM/clang and it only found a few instances of -Wunused-but-set-variable: drivers/gpu/drm/mediatek/mtk_disp_gamma.c:121:6: warning: variable 'cfg_val' set but not used [-Wunused-but-set-variable] drivers/gpu/drm/nouveau/nouveau_svm.c:115:24: warning: variable 'priority' set but not used [-Wunused-but-set-variable] drivers/gpu/drm/nouveau/nouveau_svm.c:929:6: warning: variable 'ret' set but not used [-Wunused-but-set-variable] drivers/gpu/drm/nouveau/nvkm/subdev/acr/lsfw.c:221:7: warning: variable 'loc' set but not used [-Wunused-but-set-variable] drivers/gpu/drm/qxl/qxl_cmd.c:424:6: warning: variable 'count' set but not used [-Wunused-but-set-variable] drivers/gpu/drm/qxl/qxl_ioctl.c:148:14: warning: variable 'num_relocs' set but not used [-Wunused-but-set-variable] I know that clang does not support all the warnings that are being enabled here but I suspect there won't be too many instances of the other warnings. -Wformat-overflow and -Wformat-truncation might be the big ones. I know -Wstringop-overflow is being turned on globally in -next so that is one that you shouldn't have to worry much about. Cheers, Nathan
Hi, I'm agree with you. On 2023/11/30 02:12, Jani Nikula wrote: > At least the i915 and amd drivers enable a bunch more compiler warnings > than the kernel defaults. > > Extend 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. > > Cc: David Airlie <airlied@gmail.com> > Cc: Daniel Vetter <daniel@ffwll.ch> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> > Cc: Maxime Ripard <mripard@kernel.org> > Cc: Thomas Zimmermann <tzimmermann@suse.de> > Cc: Alex Deucher <alexander.deucher@amd.com> > Cc: Christian König <christian.koenig@amd.com> > Cc: Pan, Xinhui <Xinhui.Pan@amd.com> > Cc: Karol Herbst <kherbst@redhat.com> > Cc: Lyude Paul <lyude@redhat.com> > Cc: Danilo Krummrich <dakr@redhat.com> > Cc: Rob Clark <robdclark@gmail.com> > Cc: Abhinav Kumar <quic_abhinavk@quicinc.com> > Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> > Cc: Sean Paul <sean@poorly.run> > Cc: Marijn Suijten <marijn.suijten@somainline.org> > Signed-off-by: Jani Nikula <jani.nikula@intel.com> > Acked-by: Thomas Zimmermann <tzimmermann@suse.de> > Acked-by: Javier Martinez Canillas <javierm@redhat.com> Acked-by: Sui Jingfeng <sui.jingfeng@linux.dev> > --- > > With my admittedly limited and very much x86 focused kernel config, I > get some -Wunused-but-set-variable and -Wformat-truncation= warnings, > but nothing we can't handle. > > We could fix them up front, or disable the extra warnings on a per > driver basis with a FIXME comment in their respective Makefiles. > > With the experience from i915, I think this would significantly reduce > the constant loop of warnings added by people not using W=1 and > subsequently fixed by people using W=1. > > Note: I've Cc'd the maintainers of drm, drm misc and some of the biggest > drivers. > --- > drivers/gpu/drm/Makefile | 27 +++++++++++++++++++++++++++ > 1 file changed, 27 insertions(+) > > diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile > index b4cb0835620a..6939e4ea13d5 100644 > --- a/drivers/gpu/drm/Makefile > +++ b/drivers/gpu/drm/Makefile > @@ -5,6 +5,33 @@ > > 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 += -Wmissing-declarations > +subdir-ccflags-y += $(call cc-option, -Wrestrict) > +subdir-ccflags-y += -Wmissing-format-attribute > +subdir-ccflags-y += -Wmissing-prototypes > +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) > +subdir-ccflags-y += $(call cc-option, -Wformat-truncation) > +subdir-ccflags-y += $(call cc-option, -Wstringop-overflow) > +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 \
On Thu, 30 Nov 2023 at 11:18, Maxime Ripard <mripard@kernel.org> wrote: > > Hi, > > On Thu, Nov 30, 2023 at 10:52:17AM +0200, Jani Nikula wrote: > > On Wed, 29 Nov 2023, Hamza Mahfooz <hamza.mahfooz@amd.com> wrote: > > > Cc: Nathan Chancellor <nathan@kernel.org> > > > > > > On 11/29/23 13:12, Jani Nikula wrote: > > >> At least the i915 and amd drivers enable a bunch more compiler warnings > > >> than the kernel defaults. > > >> > > >> Extend 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. > > > > > > I think this should go in after drm-misc-next has a clean build (for > > > COMPILE_TEST builds) with this patch applied. Otherwise, it will break a > > > lot of build configs. > > > > Oh, I'm absolutely not suggesting this should be merged before known > > warnings have been addressed one way or another. Either by fixing them > > or by disabling said warning in driver local Makefiles, depending on the > > case. > > I'm all for it, but yeah, we need some easy way to opt-in/opt-out. Some > drivers are pretty much unmaintained now and are likely to never fix > those warnings. Then maybe they should have the same fate as other undermaintained drivers: either they get fixed, or they get dropped?
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile index b4cb0835620a..6939e4ea13d5 100644 --- a/drivers/gpu/drm/Makefile +++ b/drivers/gpu/drm/Makefile @@ -5,6 +5,33 @@ 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 += -Wmissing-declarations +subdir-ccflags-y += $(call cc-option, -Wrestrict) +subdir-ccflags-y += -Wmissing-format-attribute +subdir-ccflags-y += -Wmissing-prototypes +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) +subdir-ccflags-y += $(call cc-option, -Wformat-truncation) +subdir-ccflags-y += $(call cc-option, -Wstringop-overflow) +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 \
At least the i915 and amd drivers enable a bunch more compiler warnings than the kernel defaults. Extend 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. Cc: David Airlie <airlied@gmail.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Maxime Ripard <mripard@kernel.org> Cc: Thomas Zimmermann <tzimmermann@suse.de> Cc: Alex Deucher <alexander.deucher@amd.com> Cc: Christian König <christian.koenig@amd.com> Cc: Pan, Xinhui <Xinhui.Pan@amd.com> Cc: Karol Herbst <kherbst@redhat.com> Cc: Lyude Paul <lyude@redhat.com> Cc: Danilo Krummrich <dakr@redhat.com> Cc: Rob Clark <robdclark@gmail.com> Cc: Abhinav Kumar <quic_abhinavk@quicinc.com> Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> Cc: Sean Paul <sean@poorly.run> Cc: Marijn Suijten <marijn.suijten@somainline.org> Signed-off-by: Jani Nikula <jani.nikula@intel.com> --- With my admittedly limited and very much x86 focused kernel config, I get some -Wunused-but-set-variable and -Wformat-truncation= warnings, but nothing we can't handle. We could fix them up front, or disable the extra warnings on a per driver basis with a FIXME comment in their respective Makefiles. With the experience from i915, I think this would significantly reduce the constant loop of warnings added by people not using W=1 and subsequently fixed by people using W=1. Note: I've Cc'd the maintainers of drm, drm misc and some of the biggest drivers. --- drivers/gpu/drm/Makefile | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+)