linux-kernel - Re: [PATCH v2] drm/i915: Disable -Wuninitialized

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Message-ID: <20190126071723.GA24759@archlinux-ryzen>
Date:   Sat, 26 Jan 2019 00:17:23 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>
Cc:     intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Chris Wilson <chris@...is-wilson.co.uk>,
        Matthias Kaehlcke <mka@...omium.org>
Subject: Re: [PATCH v2] drm/i915: Disable -Wuninitialized

On Sat, Jan 26, 2019 at 12:11:23AM -0700, Nathan Chancellor wrote:
> This warning is disabled by default in scripts/Makefile.extrawarn when
> W= is not provided but this Makefile adds -Wall after this warning is
> disabled so it shows up in the build when it shouldn't:
> 
> In file included from drivers/gpu/drm/i915/intel_breadcrumbs.c:895:
> drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c:350:34: error:
> variable 'wq' is uninitialized when used within its own initialization
> [-Werror,-Wuninitialized]
>         DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
>                                         ^~
> ./include/linux/wait.h:74:63: note: expanded from macro
> 'DECLARE_WAIT_QUEUE_HEAD_ONSTACK'
>         struct wait_queue_head name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
>                                ~~~~                                  ^~~~
> ./include/linux/wait.h:72:33: note: expanded from macro
> '__WAIT_QUEUE_HEAD_INIT_ONSTACK'
>         ({ init_waitqueue_head(&name); name; })
>                                        ^~~~
> 1 error generated.
> 
> Explicitly disable the warning like commit 46e2068081e9 ("drm/i915:
> Disable some extra clang warnings").
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/220
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
> ---
> 
> v1 -> v2:
> 
> * Rather than disable the warning for the problematic folder, disable it
>   for the entire folder like Matthias's commit.
> 

Link to v1: https://lore.kernel.org/lkml/20181025193601.11746-1-natechancellor@gmail.com/

Since I forgot '--in-reply-to' :(

>  drivers/gpu/drm/i915/Makefile | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 8300efe60fe1..210d0e8777b6 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -22,6 +22,7 @@ subdir-ccflags-y += $(call cc-disable-warning, unused-but-set-variable)
>  subdir-ccflags-y += $(call cc-disable-warning, sign-compare)
>  subdir-ccflags-y += $(call cc-disable-warning, sometimes-uninitialized)
>  subdir-ccflags-y += $(call cc-disable-warning, initializer-overrides)
> +subdir-ccflags-y += $(call cc-disable-warning, uninitialized)
>  subdir-ccflags-$(CONFIG_DRM_I915_WERROR) += -Werror
>  
>  # Fine grained warnings disable
> -- 
> 2.20.1
>