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Subject: Re: [PATCH 1/3] drm/i915/selftests: Do not use import_obj
 uninitialized
To:     Nathan Chancellor <nathan@kernel.org>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc:     Jason Ekstrand <jason@jlekstrand.net>,
        Matthew Auld <matthew.auld@intel.com>,
        "Michael J. Ruhl" <michael.j.ruhl@intel.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
        llvm@lists.linux.dev, Dan Carpenter <dan.carpenter@oracle.com>
References: <20210824225427.2065517-1-nathan@kernel.org>
 <20210824225427.2065517-2-nathan@kernel.org>
From:   =?UTF-8?Q?Thomas_Hellstr=c3=b6m?= 
        <thomas.hellstrom@linux.intel.com>
Message-ID: <ef38255f-fe4a-3ba5-e828-bac4d9957cdb@linux.intel.com>
Date:   Wed, 25 Aug 2021 11:56:35 +0200
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On 8/25/21 12:54 AM, Nathan Chancellor wrote:
> Clang warns a couple of times:
>
> drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c:63:6: warning:
> variable 'import_obj' is used uninitialized whenever 'if' condition is
> true [-Wsometimes-uninitialized]
>          if (import != &obj->base) {
>              ^~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c:80:22: note:
> uninitialized use occurs here
>          i915_gem_object_put(import_obj);
>                              ^~~~~~~~~~
> drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c:63:2: note: remove
> the 'if' if its condition is always false
>          if (import != &obj->base) {
>          ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c:38:46: note:
> initialize the variable 'import_obj' to silence this warning
>          struct drm_i915_gem_object *obj, *import_obj;
>                                                      ^
>                                                       = NULL
>
> Shuffle the import_obj initialization above these if statements so that
> it is not used uninitialized.
>
> Fixes: d7b2cb380b3a ("drm/i915/gem: Correct the locking and pin pattern for dma-buf (v8)")
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Patch looks good to me.

Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>