Re: [PATCH] erofs: Zstandard compression support

[kernel test robot <lkp@intel.com>]

Hi Gao,

kernel test robot noticed the following build warnings:

[auto build test WARNING on xiang-erofs/dev]
[also build test WARNING on next-20240508]
[cannot apply to xiang-erofs/dev-test xiang-erofs/fixes linus/master v6.9-rc7]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Gao-Xiang/erofs-Zstandard-compression-support/20240508-170754
base:   https://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git dev
patch link:    https://lore.kernel.org/r/20240508090346.2992116-1-hsiangkao%40linux.alibaba.com
patch subject: [PATCH] erofs: Zstandard compression support
config: arm64-randconfig-002-20240509 (https://download.01.org/0day-ci/archive/20240509/202405090343.ZIq0cRfw-lkp@intel.com/config)
compiler: clang version 15.0.7 (https://github.com/llvm/llvm-project.git 8dfdcc7b7bf66834a761bd8de445840ef68e4d1a)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240509/202405090343.ZIq0cRfw-lkp@intel.com/reproduce)

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>
| Closes: https://lore.kernel.org/oe-kbuild-all/202405090343.ZIq0cRfw-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> fs/erofs/decompressor_zstd.c:90:56: warning: variable 'dict_size' is uninitialized when used here [-Wuninitialized]
                   erofs_err(sb, "unsupported zstd dictionary size %u", dict_size);
                                                                        ^~~~~~~~~
   fs/erofs/internal.h:30:39: note: expanded from macro 'erofs_err'
           _erofs_err(sb, __func__, fmt "\n", ##__VA_ARGS__)
                                                ^~~~~~~~~~~
   fs/erofs/decompressor_zstd.c:80:24: note: initialize the variable 'dict_size' to silence this warning
           unsigned int dict_size, wkspsz;
                                 ^
                                  = 0
   1 warning generated.


vim +/dict_size +90 fs/erofs/decompressor_zstd.c

    74	
    75	int z_erofs_load_zstd_config(struct super_block *sb,
    76				struct erofs_super_block *dsb, void *data, int size)
    77	{
    78		static DEFINE_MUTEX(zstd_resize_mutex);
    79		struct z_erofs_zstd_cfgs *zstd = data;
    80		unsigned int dict_size, wkspsz;
    81		struct z_erofs_zstd *strm, *head = NULL;
    82		void *wksp;
    83	
    84		if (!zstd || size < sizeof(struct z_erofs_zstd_cfgs) || zstd->format) {
    85			erofs_err(sb, "unsupported zstd format, size=%u", size);
    86			return -EINVAL;
    87		}
    88	
    89		if (zstd->windowlog > ilog2(Z_EROFS_ZSTD_MAX_DICT_SIZE) - 10) {
  > 90			erofs_err(sb, "unsupported zstd dictionary size %u", dict_size);
    91			return -EINVAL;
    92		}
    93		dict_size = 1U << (zstd->windowlog + 10);
    94	
    95		/* in case 2 z_erofs_load_zstd_config() race to avoid deadlock */
    96		mutex_lock(&zstd_resize_mutex);
    97		if (z_erofs_zstd_max_dictsize >= dict_size) {
    98			mutex_unlock(&zstd_resize_mutex);
    99			return 0;
   100		}
   101	
   102		/* 1. collect/isolate all streams for the following check */
   103		while (z_erofs_zstd_avail_strms) {
   104			struct z_erofs_zstd *n;
   105	
   106			for (strm = z_erofs_isolate_strms(true); strm; strm = n) {
   107				n = strm->next;
   108				strm->next = head;
   109				head = strm;
   110				--z_erofs_zstd_avail_strms;
   111			}
   112		}
   113	
   114		/* 2. walk each isolated stream and grow max dict_size if needed */
   115		wkspsz = zstd_dstream_workspace_bound(dict_size);
   116		for (strm = head; strm; strm = strm->next) {
   117			wksp = kvmalloc(wkspsz, GFP_KERNEL);
   118			if (!wksp)
   119				break;
   120			kvfree(strm->wksp);
   121			strm->wksp = wksp;
   122			strm->wkspsz = wkspsz;
   123		}
   124	
   125		/* 3. push back all to the global list and update max dict_size */
   126		spin_lock(&z_erofs_zstd_lock);
   127		DBG_BUGON(z_erofs_zstd_head);
   128		z_erofs_zstd_head = head;
   129		spin_unlock(&z_erofs_zstd_lock);
   130		z_erofs_zstd_avail_strms = z_erofs_zstd_nstrms;
   131		wake_up_all(&z_erofs_zstd_wq);
   132		if (!strm)
   133			z_erofs_zstd_max_dictsize = dict_size;
   134		mutex_unlock(&zstd_resize_mutex);
   135		return strm ? -ENOMEM : 0;
   136	}
   137	

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