Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <ea7d5e53-c008-4833-a24c-a17522ce96b5@amd.com>
Date:   Fri, 18 Feb 2022 11:15:06 -0500
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.5.0
Subject: Re: [PATCH] drm/amdkfd: Replace one-element array with flexible-array
 member
Content-Language: en-US
To:     =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>,
        cgel.zte@gmail.com
Cc:     alexander.deucher@amd.com, Xinhui.Pan@amd.com, airlied@linux.ie,
        daniel@ffwll.ch, amd-gfx@lists.freedesktop.org,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        Changcheng Deng <deng.changcheng@zte.com.cn>,
        Zeal Robot <zealci@zte.com.cn>
References: <20220218030943.1905838-1-deng.changcheng@zte.com.cn>
 <cbc80795-af46-21fd-dc9f-ce932be76d4f@amd.com>
From:   Felix Kuehling <felix.kuehling@amd.com>
In-Reply-To: <cbc80795-af46-21fd-dc9f-ce932be76d4f@amd.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?Y2h4aG16VGxIczhUUzZmL29STzg0Wkt1RTAxV1o3MFJXRXJFM3JLMEd6ZHBp?=
 =?utf-8?B?dktSSzViS1l6TjI5L0IwQjkxNEJQK25VWnQ4ZFIrb3dLL2JwNEdnYXFGNGVu?=
 =?utf-8?B?cjZyQU4zeElPVE1zc0l4VXJ0dzJuVmgrZ0V2L2ZBd3FOT1FzTmFIYU5TZmlM?=
 =?utf-8?B?UWhWUS9jZnVKRElVbTFxRXFRdTMyRDBVU3NvYWNRdHlOdnlvdEpGZExBRFdC?=
 =?utf-8?B?eWovZWtSbFZIOHZVVC9FbEhMZUcza1FvRXVPZHh4cS8wUlpKSlA2S1lTRGRk?=
 =?utf-8?B?VE9IVERuVnV1aTVsWFNZM1ZJT283OFAzU00xb3FJTTFHNU1yVkN6NlVJL3pJ?=
 =?utf-8?B?aGlhblVEdDZzVnFIYVlaVjVzaHlxSTA0UzJ5MGliR2VPeUVNWVM5OVJBTGFB?=
 =?utf-8?B?OCs0TGpLbk1rL0NCWUsrQ0RFNUJIY3dKbGpJTEd2NTJKM2NJZk8rSDN1YkJM?=
 =?utf-8?B?NmsyeXRNakQ1aEZSTDJ0ekpvQTF1TWQ1bHVPR3c5dUo3SUtqeDVJSStOQWdi?=
 =?utf-8?B?Zi94VE5qbG5iNysxamI3QkN1a05rclZUSXVpbENJQmxQN0VveHVORy8yemF6?=
 =?utf-8?B?cUZ6VktIZjRHekl3cHpRc3dxb0FQM1BnNm5VQlpqUVI0b1RhcW93WS9USThr?=
 =?utf-8?B?dSt6eVhhMEtJQmplVDNmMWxEU21mQjFYWmZCaTQ1blRrd2xDbWxVUEFvLzlM?=
 =?utf-8?B?b1NnTjM2MDhUaGFQUVg2Sk9QeGZrekVJajAzV3d5RXZaTDZ5WTZQZHhUUCtD?=
 =?utf-8?B?K1hCU0RoY3RyeGJFdjlsYWc1bG9MbStVKzcxa3hiMXZnNFdBRk5Qb0haazVY?=
 =?utf-8?B?WGpHZTlLU0pMRFFhMjhtc2lUUmx2NTgyb0lXb09qNVRkKzAxbDZOcmFYZkZ6?=
 =?utf-8?B?YTBLTlVBY1dTYW5Tb1Zjb1B3RzQxK2JISnQzMlIwOHFOQTlTNzgwdEhtVmgv?=
 =?utf-8?B?b1J6d0FiNG1rc29DdStTaUVlN2FtQ1EwNFNUN2p0WUhkaTdRdCtweW1FUWh3?=
 =?utf-8?B?dnpEeXJTVW5wVDN6QUxIU3BjZFo2ekpZaWxHWDdHYVJTQW05eXRRUnM5V0VY?=
 =?utf-8?B?YitxVVN0ZU41bzAvelRXNS9NYU0weFNBRWFnM3YxcU1IclVqY2oyc2xlaFdu?=
 =?utf-8?B?OEZHaWVvZXY1d3o5OGxzNWxjSnR3NHk4SUI3OWdvM1pxWS9XcEVMcW1RQnVu?=
 =?utf-8?B?NkdSd1VmNUNIVyt4UGcrRmpYYi9ZWVUvM0Q3RWUzYm1JdHNqVUVDYjRrd3Vj?=
 =?utf-8?B?Y1BwY2QvM01vdkl4WDlNME1CNENCQTlxNzFHOWFqVG56WndBS0FYNWxVRWdB?=
 =?utf-8?B?OVN6WWNMSDBBNEpTMmRjMitGeFNZWVVtcjNrVG9zMnQvbklDRjFoUCttSDdK?=
 =?utf-8?B?TGZhbVNGd1U0Mnc0L0tNL0x0dUFUMnJRTFB3UW9qaHoveFBoZHNnS0FyNzFn?=
 =?utf-8?B?TWhQcXBjUDJGRGFXaDVyd2lXUllIazU3dWcxZUQ5Z1FmV04xSDBveGRidTFI?=
 =?utf-8?B?dHphNXJSeXIreTcvVGdPOUJZanIwR216UkZERDB3WkcyWjN4K3NSRlRqWkc1?=
 =?utf-8?B?ekhUeE04dm5WMzN6QkZNR2hNdnprT0l3QTFJZEJWL25lNzJjWWtFTzUxVUZ3?=
 =?utf-8?B?VGQ5QTAxa054M2dQQkJxWjRJMm9PNCs3K2lsOXNBaTZYeHRTY2ZCS2RoRVIy?=
 =?utf-8?B?Y3hPMklkV0hRZHVjSTkraFo3dnNPMCtXVjc1YUUxVWlQL2pRNDdVd0UyTFB6?=
 =?utf-8?B?eUhBU3E3andzSmo1RGJPazlWTUQzKzFEOUNnU1cyc1ZLREVGTUdlVjYwSmdr?=
 =?utf-8?B?N01IdFkzd1E1bVViTFduY0wrSCtWUWlnSnZ1bElyYUtXQi9LZjlxeC9ubDlJ?=
 =?utf-8?B?NDRKRHIrbTRiK1RQc2dCOHFoeW1KVWJKdGxiRUtRdUxnS2p5c2VpMDA0NDVo?=
 =?utf-8?B?OHhxZjE5dkVlUmhFd0dDWFlqRS92dUZEai9TVTVYZVgxc1BON216cU9wUzM5?=
 =?utf-8?B?WUJzSmZ5aEsvT2dYR1ZJTDBlNnV2L0pwVzFTRm1obTRzZStLUnFBeWlnYUFL?=
 =?utf-8?B?SWpwM1djRzZpdDNEcGhCdkFPQWFBK1VRUjQvUXJ1VXMxdjFvcnVJWFBWeVQ3?=
 =?utf-8?B?U25CcERpWnVKTk1IZ3JUNW5Gd0FHay9CcFhxQW1WMk1xTStJaXVNdENqZ3lH?=
 =?utf-8?Q?IC22xooD2ZyxEcVO7kQLskM=3D?=
X-OriginatorOrg: amd.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 11e0fe99-6c2c-4f00-60f4-08d9f2f9d4c6
X-MS-Exchange-CrossTenant-AuthSource: BN9PR12MB5115.namprd12.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Feb 2022 16:15:08.1746
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: 7+a4frzXf95jNmfI4AZFkfCPTfCtzN6VNQWrCWZIPxMlKrKlKj2vjPSpqoOAWP2283nZ4SPBOxZGSMRNkNnblw==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR12MB4534
X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,RCVD_IN_DNSWL_NONE,
        RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS,T_SCC_BODY_TEXT_LINE
        autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

It looks like this structure isn't being used at all. So I'm OK with 
this change, in case we ever use it in the future.

Regards,
   Felix


Am 2022-02-18 um 02:47 schrieb Christian König:
> Felix need to comment as well, but I don't think that this will work 
> that easily.
>
> By changing the entry from 1 to 0 your are also changing the size of 
> the structure.
>
> Regards,
> Christian.
>
> Am 18.02.22 um 04:09 schrieb cgel.zte@gmail.com:
>> From: Changcheng Deng <deng.changcheng@zte.com.cn>
>>
>> There is a regular need in the kernel to provide a way to declare having
>> a dynamically sized set of trailing elements in a structure. Kernel code
>> should always use "flexible array members" for these cases. The older
>> style of one-element or zero-length arrays should no longer be used.
>> Reference:
>> https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays 
>>
>>
>> Reported-by: Zeal Robot <zealci@zte.com.cn>
>> Signed-off-by: Changcheng Deng <deng.changcheng@zte.com.cn>
>> ---
>>   drivers/gpu/drm/amd/amdkfd/kfd_crat.h | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_crat.h 
>> b/drivers/gpu/drm/amd/amdkfd/kfd_crat.h
>> index 482ba84a728d..d7c38fbc533e 100644
>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_crat.h
>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_crat.h
>> @@ -310,7 +310,7 @@ struct cdit_header {
>>       uint32_t    creator_revision;
>>       uint32_t    total_entries;
>>       uint16_t    num_domains;
>> -    uint8_t        entry[1];
>> +    uint8_t        entry[];
>>   };
>>     #pragma pack()
>