Hi

On Wed, Feb 14, 2018 at 9:27 PM, kbuild test robot
[off-list ref] wrote:

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git vhost
head:   5d457fe6aeaab9d0a1665eafc8af7139bc6b6f2e
commit: 5d457fe6aeaab9d0a1665eafc8af7139bc6b6f2e [24/24] fw_cfg: fix sparse warnings around FW_CFG_FILE_DIR read
config: i386-randconfig-x015-201806 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
        git checkout 5d457fe6aeaab9d0a1665eafc8af7139bc6b6f2e
        # save the attached .config to linux build tree
        make ARCH=i386

All errors (new ones prefixed by >>):

   drivers/firmware/qemu_fw_cfg.c: In function 'fw_cfg_register_dir_entries':

quoted

quoted

drivers/firmware/qemu_fw_cfg.c:499:22: error: storage size of 'files' isn't known

     struct fw_cfg_files files;
                         ^~~~~

struct fw_cfg_files {
        __be32 count; /* number of entries */
        struct fw_cfg_file f[];
};

Interesting, I don't have that warning with 7.3.1.

I thought the size would be sizeof(count) by standard.

I replaced it with a __be32 files_count variable instead.

   drivers/firmware/qemu_fw_cfg.c:499:22: warning: unused variable 'files' [-Wunused-variable]

files.count is used 3 lines below, that looks like a compiler bug to me.

vim +499 drivers/firmware/qemu_fw_cfg.c

   493
   494  /* iterate over all fw_cfg directory entries, registering each one */
   495  static int fw_cfg_register_dir_entries(void)
   496  {
   497          int ret = 0;
   498          u32 count, i;
 > 499          struct fw_cfg_files files;
   500          struct fw_cfg_file *dir;
   501          size_t dir_size;
   502
   503          fw_cfg_read_blob(FW_CFG_FILE_DIR, &files.count, 0, sizeof(files.count));
   504          count = be32_to_cpu(files.count);
   505          dir_size = count * sizeof(struct fw_cfg_file);
   506
   507          dir = kmalloc(dir_size, GFP_KERNEL);
   508          if (!dir)
   509                  return -ENOMEM;
   510
   511          fw_cfg_read_blob(FW_CFG_FILE_DIR, dir, sizeof(files.count), dir_size);
   512
   513          for (i = 0; i < count; i++) {
   514                  ret = fw_cfg_register_file(&dir[i]);
   515                  if (ret)
   516                          break;
   517          }
   518
   519          kfree(dir);
   520          return ret;
   521  }
   522

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