Re: [PATCH 01/12] kbuild: make -Woverride-init warnings more consistent

From: Jani Nikula <jani.nikula@linux.intel.com>
To: "Arnd Bergmann" <arnd@arndb.de>,
	"Arnd Bergmann" <arnd@kernel.org>,
	linux-kbuild@vger.kernel.org,
	"Masahiro Yamada" <masahiroy@kernel.org>,
	"Harry Wentland" <harry.wentland@amd.com>,
	"Alex Deucher" <alexander.deucher@amd.com>,
	"Christian König" <christian.koenig@amd.com>,
	"Lucas De Marchi" <lucas.demarchi@intel.com>,
	"Oded Gabbay" <ogabbay@kernel.org>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Maxime Ripard" <mripard@kernel.org>,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Andrew Jeffery" <andrew@codeconstruct.com.au>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	"Joel Stanley" <joel@jms.id.au>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Nathan Chancellor" <nathan@kernel.org>
Cc: Nicolas Schier <nicolas@fjasle.eu>,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	Netdev <netdev@vger.kernel.org>,
	linux-mm@kvack.org, llvm@lists.linux.dev
Subject: Re: [PATCH 01/12] kbuild: make -Woverride-init warnings more consistent
Date: Wed, 27 Mar 2024 09:50:05 +0200	[thread overview]
Message-ID: <87edbwglle.fsf@intel.com> (raw)
In-Reply-To: <cb853762-06d4-401c-a1c8-07a0c031b499@app.fastmail.com>

On Tue, 26 Mar 2024, "Arnd Bergmann" <arnd@arndb.de> wrote:
> On Tue, Mar 26, 2024, at 21:24, Jani Nikula wrote:
>> On Tue, 26 Mar 2024, Arnd Bergmann <arnd@kernel.org> wrote:
>>> From: Arnd Bergmann <arnd@arndb.de>
>>> index 475e1e8c1d35..0786eb0da391 100644
>>> --- a/drivers/net/ethernet/renesas/sh_eth.c
>>> +++ b/drivers/net/ethernet/renesas/sh_eth.c
>>> @@ -50,7 +50,7 @@
>>>   * the macros available to do this only define GCC 8.
>>>   */
>>>  __diag_push();
>>> -__diag_ignore(GCC, 8, "-Woverride-init",
>>> +__diag_ignore_all("-Woverride-init",
>>>  	      "logic to initialize all and then override some is OK");
>>
>> This is nice because it's more localized than the per-file
>> disable. However, we tried to do this in i915, but this doesn't work for
>> GCC versions < 8, and some defconfigs enabling -Werror forced us to
>> revert. See commit 290d16104575 ("Revert "drm/i915: use localized
>> __diag_ignore_all() instead of per file"").
>
> It works now.
>
> The original __diag_ignore_all() only did it for gcc-8 and above
> because that was initially needed to suppress warnings that
> got added in that version, but this was always a mistake.
>
> 689b097a06ba ("compiler-gcc: Suppress -Wmissing-prototypes
> warning for all supported GCC") made it work correctly.

Oh, nice! Then I think we'd like to go back to __diag_ignore_all() in
i915 and xe.

The diff is below. I'm fine with you squashing it to your patch, or if
you want me to turn it into a proper patch for you to pick up in your
series, that's fine too. Just let me know.

BR,
Jani.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 3ef6ed41e62b..87d6ba8d2341 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -32,11 +32,6 @@ endif
 # Enable -Werror in CI and development
 subdir-ccflags-$(CONFIG_DRM_I915_WERROR) += -Werror
 
-# Fine grained warnings disable
-CFLAGS_i915_pci.o = $(call cc-disable-warning, override-init)
-CFLAGS_display/intel_display_device.o = $(call cc-disable-warning, override-init)
-CFLAGS_display/intel_fbdev.o = $(call cc-disable-warning, override-init)
-
 # Support compiling the display code separately for both i915 and xe
 # drivers. Define I915 when building i915.
 subdir-ccflags-y += -DI915
diff --git a/drivers/gpu/drm/i915/display/intel_display_device.c b/drivers/gpu/drm/i915/display/intel_display_device.c
index c02d79b50006..b8903bd0e82a 100644
--- a/drivers/gpu/drm/i915/display/intel_display_device.c
+++ b/drivers/gpu/drm/i915/display/intel_display_device.c
@@ -17,6 +17,9 @@
 #include "intel_display_reg_defs.h"
 #include "intel_fbc.h"
 
+__diag_push();
+__diag_ignore_all("-Woverride-init", "Allow field initialization overrides for display info");
+
 static const struct intel_display_device_info no_display = {};
 
 #define PIPE_A_OFFSET		0x70000
@@ -768,6 +771,8 @@ static const struct intel_display_device_info xe2_lpd_display = {
 		BIT(INTEL_FBC_C) | BIT(INTEL_FBC_D),
 };
 
+__diag_pop();
+
 /*
  * Separate detection for no display cases to keep the display id array simple.
  *
diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.c b/drivers/gpu/drm/i915/display/intel_fbdev.c
index 99894a855ef0..43855c6c3509 100644
--- a/drivers/gpu/drm/i915/display/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/display/intel_fbdev.c
@@ -135,6 +135,9 @@ static int intel_fbdev_mmap(struct fb_info *info, struct vm_area_struct *vma)
 	return i915_gem_fb_mmap(obj, vma);
 }
 
+__diag_push();
+__diag_ignore_all("-Woverride-init", "Allow field initialization overrides for fb ops");
+
 static const struct fb_ops intelfb_ops = {
 	.owner = THIS_MODULE,
 	__FB_DEFAULT_DEFERRED_OPS_RDWR(intel_fbdev),
@@ -146,6 +149,8 @@ static const struct fb_ops intelfb_ops = {
 	.fb_mmap = intel_fbdev_mmap,
 };
 
+__diag_pop();
+
 static int intelfb_create(struct drm_fb_helper *helper,
 			  struct drm_fb_helper_surface_size *sizes)
 {
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c
index 1e69783ae4fd..405ca17a990b 100644
--- a/drivers/gpu/drm/i915/i915_pci.c
+++ b/drivers/gpu/drm/i915/i915_pci.c
@@ -38,6 +38,9 @@
 #include "i915_reg.h"
 #include "intel_pci_config.h"
 
+__diag_push();
+__diag_ignore_all("-Woverride-init", "Allow field initialization overrides for device info");
+
 #define PLATFORM(x) .platform = (x)
 #define GEN(x) \
 	.__runtime.graphics.ip.ver = (x), \
@@ -785,6 +788,8 @@ static const struct intel_device_info mtl_info = {
 
 #undef PLATFORM
 
+__diag_pop();
+
 /*
  * Make sure any device matches here are from most specific to most
  * general.  For example, since the Quanta match is based on the subsystem
diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
index 3c3e67885559..2f58faf0a79a 100644
--- a/drivers/gpu/drm/xe/Makefile
+++ b/drivers/gpu/drm/xe/Makefile
@@ -172,9 +172,6 @@ subdir-ccflags-$(CONFIG_DRM_XE_DISPLAY) += \
 	-Ddrm_i915_gem_object=xe_bo \
 	-Ddrm_i915_private=xe_device
 
-CFLAGS_i915-display/intel_fbdev.o = $(call cc-disable-warning, override-init)
-CFLAGS_i915-display/intel_display_device.o = $(call cc-disable-warning, override-init)
-
 # Rule to build SOC code shared with i915
 $(obj)/i915-soc/%.o: $(srctree)/drivers/gpu/drm/i915/soc/%.c FORCE
 	$(call cmd,force_checksrc)

-- 
Jani Nikula, Intel
