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Date:   Tue, 13 Sep 2022 16:19:09 -0700
From:   Nathan Chancellor <nathan@kernel.org>
To:     Nathan Huckleberry <nhuck@google.com>
Cc:     Dan Carpenter <error27@gmail.com>, llvm@lists.linux.dev,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>,
        Matt Roper <matthew.d.roper@intel.com>,
        Lucas De Marchi <lucas.demarchi@intel.com>,
        intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/i915: Fix return type of mode_valid function hook
Message-ID: <YyEP7W/yZAyhNtTX@dev-arch.thelio-3990X>
References: <20220913205531.155046-1-nhuck@google.com>
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On Tue, Sep 13, 2022 at 01:55:27PM -0700, Nathan Huckleberry wrote:
> All of the functions used for intel_dvo_dev_ops.mode_valid have a return
> type of enum drm_mode_status, but the mode_valid field in the struct
> definition has a return type of int.
> 
> The mismatched return type breaks forward edge kCFI since the underlying
> function definitions do not match the function hook definition.
> 
> The return type of the mode_valid field should be changed from int to
> enum drm_mode_status.
> 
> Reported-by: Dan Carpenter <error27@gmail.com>
> Link: https://github.com/ClangBuiltLinux/linux/issues/1703
> Cc: llvm@lists.linux.dev
> Signed-off-by: Nathan Huckleberry <nhuck@google.com>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
>  drivers/gpu/drm/i915/display/intel_dvo_dev.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dvo_dev.h b/drivers/gpu/drm/i915/display/intel_dvo_dev.h
> index d96c3cc46e50..50205f064d93 100644
> --- a/drivers/gpu/drm/i915/display/intel_dvo_dev.h
> +++ b/drivers/gpu/drm/i915/display/intel_dvo_dev.h
> @@ -75,8 +75,8 @@ struct intel_dvo_dev_ops {
>  	 *
>  	 * \return MODE_OK if the mode is valid, or another MODE_* otherwise.
>  	 */
> -	int (*mode_valid)(struct intel_dvo_device *dvo,
> -			  struct drm_display_mode *mode);
> +	enum drm_mode_status (*mode_valid)(struct intel_dvo_device *dvo,
> +					   struct drm_display_mode *mode);
>  
>  	/*
>  	 * Callback for preparing mode changes on an output
> -- 
> 2.37.2.789.g6183377224-goog
>