Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH] drm/amdgpu/virt: don't dereference undefined 'module'
 struct
To:     Arnd Bergmann <arnd@arndb.de>,
        Alex Deucher <alexander.deucher@amd.com>,
        =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>
Cc:     David Airlie <airlied@linux.ie>, Horace Chen <horace.chen@amd.com>,
        linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org,
        Xiangliang Yu <Xiangliang.Yu@amd.com>,
        dri-devel@lists.freedesktop.org, Monk Liu <Monk.Liu@amd.com>
References: <20171102112619.72157-1-arnd@arndb.de>
From:   Harry Wentland <harry.wentland@amd.com>
Message-ID: <afba5139-ec05-69a6-fe8f-b8b3d434f2d1@amd.com>
Date:   Thu, 2 Nov 2017 15:22:05 -0400
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.4.0
MIME-Version: 1.0
In-Reply-To: <20171102112619.72157-1-arnd@arndb.de>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Received-SPF: None (protection.outlook.com: amd.com does not designate
 permitted sender hosts)
SpamDiagnosticOutput: 1:99
SpamDiagnosticMetadata: NSPM
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Nov 2017 19:22:09.0211 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: b9c6bdff-fce3-4451-caaf-08d52227038f
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN6PR1201MB2467
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 2017-11-02 07:25 AM, Arnd Bergmann wrote:
> Accessing the THIS_MODULE directly is only possible when modules
> are enabled, otherwise we get a build failure:
> 
> drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c: In function 'amdgpu_virt_init_data_exchange':
> drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c:331:20: error: dereferencing pointer to incomplete type 'struct module'
> 
> Further, THIS_MODULE is NULL when the driver is built-in, so the
> code would likely cause a NULL pointer dereference.
> 
> This adds an #ifdef check to avoid the compile-time error, plus
> a NULL pointer check before dereferencing THIS_MODULE. It might
> be better to find a way to avoid using the module version
> altogether.
> 
> Fixes: 2dc8f81e4f82 ("drm/amdgpu: SR-IOV data exchange between PF&VF")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Looks like 'str' isn't even used here.

Either way, this change by itself is correct and
Reviewed-by: Harry Wentland <harry.wentland@amd.com>

Harry

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
> index e97f80f86005..4e4a476593e8 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
> @@ -328,9 +328,11 @@ void amdgpu_virt_init_data_exchange(struct amdgpu_device *adev)
>  					sizeof(amdgim_vf2pf_info));
>  				AMDGPU_FW_VRAM_VF2PF_READ(adev, driver_version,
>  					&str);
> +#ifdef MODULE
>  				if (THIS_MODULE->version != NULL)
>  					strcpy(str, THIS_MODULE->version);
>  				else
> +#endif
>  					strcpy(str, "N/A");
>  				AMDGPU_FW_VRAM_VF2PF_WRITE(adev, driver_cert,
>  					0);
> 

From 1582953443006848179@xxx Thu Nov 02 11:27:22 +0000 2017
X-GM-THRID: 1582953443006848179
X-Gmail-Labels: Inbox,Category Forums,HistoricalUnread