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Date: Mon, 6 May 2024 09:19:03 -0500
From: Lucas De Marchi <lucas.demarchi@intel.com>
To: Julia Lawall <julia.lawall@inria.fr>
CC: Matt Roper <matthew.d.roper@intel.com>, <linux-kernel@vger.kernel.org>,
	<oe-kbuild-all@lists.linux.dev>
Subject: Re: drivers/gpu/drm/xe/xe_guc_ads.c:103:21-27: WARNING use
 flexible-array member instead
 (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
 (fwd)
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On Sun, May 05, 2024 at 01:17:59PM GMT, Julia Lawall wrote:
>Can a flexible array be used at the end of this structure?

yes, we should. Just submitted a fix. Thanks

Lucas De Marchi

>
>julia
>
>---------- Forwarded message ----------
>Date: Sun, 5 May 2024 19:06:22 +0800
>From: kernel test robot <lkp@intel.com>
>To: oe-kbuild@lists.linux.dev
>Cc: lkp@intel.com, Julia Lawall <julia.lawall@inria.fr>
>Subject: drivers/gpu/drm/xe/xe_guc_ads.c:103:21-27: WARNING use flexible-array
>    member instead
>    (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-
>    and-one-element-arrays)
>
>BCC: lkp@intel.com
>CC: oe-kbuild-all@lists.linux.dev
>CC: linux-kernel@vger.kernel.org
>TO: Lucas De Marchi <lucas.demarchi@intel.com>
>CC: Matt Roper <matthew.d.roper@intel.com>
>
>tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>head:   7367539ad4b0f8f9b396baf02110962333719a48
>commit: 237412e45390805e14a6936fb998d756c4eac9d8 drm/xe: Enable 32bits build
>date:   3 months ago
>:::::: branch date: 2 days ago
>:::::: commit date: 3 months ago
>config: i386-randconfig-054-20240505 (https://download.01.org/0day-ci/archive/20240505/202405051824.AmjAI5Pg-lkp@intel.com/config)
>compiler: clang version 18.1.4 (https://github.com/llvm/llvm-project e6c3289804a67ea0bb6a86fadbe454dd93b8d855)
>
>If you fix the issue in a separate patch/commit (i.e. not just a new version of
>the same patch/commit), kindly add following tags
>| Reported-by: kernel test robot <lkp@intel.com>
>| Reported-by: Julia Lawall <julia.lawall@inria.fr>
>| Closes: https://lore.kernel.org/r/202405051824.AmjAI5Pg-lkp@intel.com/
>
>cocci warnings: (new ones prefixed by >>)
>>> drivers/gpu/drm/xe/xe_guc_ads.c:103:21-27: WARNING use flexible-array member instead (https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays)
>
>vim +103 drivers/gpu/drm/xe/xe_guc_ads.c
>
>dd08ebf6c3525a Matthew Brost 2023-03-30   53
>dd08ebf6c3525a Matthew Brost 2023-03-30   54  /*
>dd08ebf6c3525a Matthew Brost 2023-03-30   55   * The Additional Data Struct (ADS) has pointers for different buffers used by
>dd08ebf6c3525a Matthew Brost 2023-03-30   56   * the GuC. One single gem object contains the ADS struct itself (guc_ads) and
>dd08ebf6c3525a Matthew Brost 2023-03-30   57   * all the extra buffers indirectly linked via the ADS struct's entries.
>dd08ebf6c3525a Matthew Brost 2023-03-30   58   *
>dd08ebf6c3525a Matthew Brost 2023-03-30   59   * Layout of the ADS blob allocated for the GuC:
>dd08ebf6c3525a Matthew Brost 2023-03-30   60   *
>dd08ebf6c3525a Matthew Brost 2023-03-30   61   *      +---------------------------------------+ <== base
>dd08ebf6c3525a Matthew Brost 2023-03-30   62   *      | guc_ads                               |
>dd08ebf6c3525a Matthew Brost 2023-03-30   63   *      +---------------------------------------+
>dd08ebf6c3525a Matthew Brost 2023-03-30   64   *      | guc_policies                          |
>dd08ebf6c3525a Matthew Brost 2023-03-30   65   *      +---------------------------------------+
>dd08ebf6c3525a Matthew Brost 2023-03-30   66   *      | guc_gt_system_info                    |
>dd08ebf6c3525a Matthew Brost 2023-03-30   67   *      +---------------------------------------+
>dd08ebf6c3525a Matthew Brost 2023-03-30   68   *      | guc_engine_usage                      |
>dd08ebf6c3525a Matthew Brost 2023-03-30   69   *      +---------------------------------------+
>dd08ebf6c3525a Matthew Brost 2023-03-30   70   *      | guc_um_init_params                    |
>dd08ebf6c3525a Matthew Brost 2023-03-30   71   *      +---------------------------------------+ <== static
>dd08ebf6c3525a Matthew Brost 2023-03-30   72   *      | guc_mmio_reg[countA] (engine 0.0)     |
>dd08ebf6c3525a Matthew Brost 2023-03-30   73   *      | guc_mmio_reg[countB] (engine 0.1)     |
>dd08ebf6c3525a Matthew Brost 2023-03-30   74   *      | guc_mmio_reg[countC] (engine 1.0)     |
>dd08ebf6c3525a Matthew Brost 2023-03-30   75   *      |   ...                                 |
>dd08ebf6c3525a Matthew Brost 2023-03-30   76   *      +---------------------------------------+ <== dynamic
>dd08ebf6c3525a Matthew Brost 2023-03-30   77   *      | padding                               |
>dd08ebf6c3525a Matthew Brost 2023-03-30   78   *      +---------------------------------------+ <== 4K aligned
>dd08ebf6c3525a Matthew Brost 2023-03-30   79   *      | golden contexts                       |
>dd08ebf6c3525a Matthew Brost 2023-03-30   80   *      +---------------------------------------+
>dd08ebf6c3525a Matthew Brost 2023-03-30   81   *      | padding                               |
>dd08ebf6c3525a Matthew Brost 2023-03-30   82   *      +---------------------------------------+ <== 4K aligned
>dd08ebf6c3525a Matthew Brost 2023-03-30   83   *      | capture lists                         |
>dd08ebf6c3525a Matthew Brost 2023-03-30   84   *      +---------------------------------------+
>dd08ebf6c3525a Matthew Brost 2023-03-30   85   *      | padding                               |
>dd08ebf6c3525a Matthew Brost 2023-03-30   86   *      +---------------------------------------+ <== 4K aligned
>dd08ebf6c3525a Matthew Brost 2023-03-30   87   *      | UM queues                             |
>dd08ebf6c3525a Matthew Brost 2023-03-30   88   *      +---------------------------------------+
>dd08ebf6c3525a Matthew Brost 2023-03-30   89   *      | padding                               |
>dd08ebf6c3525a Matthew Brost 2023-03-30   90   *      +---------------------------------------+ <== 4K aligned
>dd08ebf6c3525a Matthew Brost 2023-03-30   91   *      | private data                          |
>dd08ebf6c3525a Matthew Brost 2023-03-30   92   *      +---------------------------------------+
>dd08ebf6c3525a Matthew Brost 2023-03-30   93   *      | padding                               |
>dd08ebf6c3525a Matthew Brost 2023-03-30   94   *      +---------------------------------------+ <== 4K aligned
>dd08ebf6c3525a Matthew Brost 2023-03-30   95   */
>dd08ebf6c3525a Matthew Brost 2023-03-30   96  struct __guc_ads_blob {
>dd08ebf6c3525a Matthew Brost 2023-03-30   97  	struct guc_ads ads;
>dd08ebf6c3525a Matthew Brost 2023-03-30   98  	struct guc_policies policies;
>dd08ebf6c3525a Matthew Brost 2023-03-30   99  	struct guc_gt_system_info system_info;
>dd08ebf6c3525a Matthew Brost 2023-03-30  100  	struct guc_engine_usage engine_usage;
>dd08ebf6c3525a Matthew Brost 2023-03-30  101  	struct guc_um_init_params um_init_params;
>dd08ebf6c3525a Matthew Brost 2023-03-30  102  	/* From here on, location is dynamic! Refer to above diagram. */
>dd08ebf6c3525a Matthew Brost 2023-03-30 @103  	struct guc_mmio_reg regset[0];
>dd08ebf6c3525a Matthew Brost 2023-03-30  104  } __packed;
>dd08ebf6c3525a Matthew Brost 2023-03-30  105
>
>:::::: The code at line 103 was first introduced by commit
>:::::: dd08ebf6c3525a7ea2186e636df064ea47281987 drm/xe: Introduce a new DRM driver for Intel GPUs
>
>:::::: TO: Matthew Brost <matthew.brost@intel.com>
>:::::: CC: Rodrigo Vivi <rodrigo.vivi@intel.com>
>
>-- 
>0-DAY CI Kernel Test Service
>https://github.com/intel/lkp-tests/wiki