[arnd-playground:y2038-endgame 74/88] drivers/media/v4l2-core/v4l2-compat-ioctl32.c:117:7: warning: 'ncmd' may be used uninitialized in this function

[arnd-playground:y2038-endgame 74/88] drivers/media/v4l2-core/v4l2-compat-ioctl32.c:117:7: warning: 'ncmd' may be used uninitialized in this function

[kbuild test robot]

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git y2038-endgame
head:   6f76dcc2f041801fc5ce6e418ef8912a24244436
commit: 36582e064bce5ab1e39b5eb3da1832aeb47911ad [74/88] media: v4l2-core: fix compat VIDIOC_DQEVENT for time64 ABI
config: x86_64-rhel (attached as .config)
compiler: gcc-7 (Debian 7.4.0-14) 7.4.0
reproduce:
        git checkout 36582e064bce5ab1e39b5eb3da1832aeb47911ad
        # save the attached .config to linux build tree
        make ARCH=x86_64 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

   drivers/media/v4l2-core/v4l2-compat-ioctl32.c: In function 'do_video_ioctl':
>> drivers/media/v4l2-core/v4l2-compat-ioctl32.c:117:7: warning: 'ncmd' may be used uninitialized in this function [-Wmaybe-uninitialized]
      ret = file->f_op->unlocked_ioctl(file, cmd, arg);
      ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/media/v4l2-core/v4l2-compat-ioctl32.c:1226:15: note: 'ncmd' was declared here
     unsigned int ncmd;
                  ^~~~

vim +/ncmd +117 drivers/media/v4l2-core/v4l2-compat-ioctl32.c

09c033b66596a9 drivers/media/v4l2-core/v4l2-compat-ioctl32.c Mauro Carvalho Chehab 2018-04-17  101  
1d338b86e17d87 drivers/media/v4l2-core/v4l2-compat-ioctl32.c Mauro Carvalho Chehab 2018-04-19  102  /**
1d338b86e17d87 drivers/media/v4l2-core/v4l2-compat-ioctl32.c Mauro Carvalho Chehab 2018-04-19  103   * native_ioctl - Ancillary function that calls the native 64 bits ioctl
1d338b86e17d87 drivers/media/v4l2-core/v4l2-compat-ioctl32.c Mauro Carvalho Chehab 2018-04-19  104   * handler.
1d338b86e17d87 drivers/media/v4l2-core/v4l2-compat-ioctl32.c Mauro Carvalho Chehab 2018-04-19  105   *
1d338b86e17d87 drivers/media/v4l2-core/v4l2-compat-ioctl32.c Mauro Carvalho Chehab 2018-04-19  106   * @file: pointer to &struct file with the file handler
1d338b86e17d87 drivers/media/v4l2-core/v4l2-compat-ioctl32.c Mauro Carvalho Chehab 2018-04-19  107   * @cmd: ioctl to be called
1d338b86e17d87 drivers/media/v4l2-core/v4l2-compat-ioctl32.c Mauro Carvalho Chehab 2018-04-19  108   * @arg: arguments passed from/to the ioctl handler
1d338b86e17d87 drivers/media/v4l2-core/v4l2-compat-ioctl32.c Mauro Carvalho Chehab 2018-04-19  109   *
1d338b86e17d87 drivers/media/v4l2-core/v4l2-compat-ioctl32.c Mauro Carvalho Chehab 2018-04-19  110   * This function calls the native ioctl handler at v4l2-dev, e. g. v4l2_ioctl()
1d338b86e17d87 drivers/media/v4l2-core/v4l2-compat-ioctl32.c Mauro Carvalho Chehab 2018-04-19  111   */
069b747931f13e drivers/media/video/v4l2-compat-ioctl32.c     Hans Verkuil          2008-12-30  112  static long native_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
92f45badbbaccd drivers/media/video/v4l2-compat-ioctl32.c     Hans Verkuil          2008-12-21  113  {
069b747931f13e drivers/media/video/v4l2-compat-ioctl32.c     Hans Verkuil          2008-12-30  114  	long ret = -ENOIOCTLCMD;
92f45badbbaccd drivers/media/video/v4l2-compat-ioctl32.c     Hans Verkuil          2008-12-21  115  
92f45badbbaccd drivers/media/video/v4l2-compat-ioctl32.c     Hans Verkuil          2008-12-21  116  	if (file->f_op->unlocked_ioctl)
92f45badbbaccd drivers/media/video/v4l2-compat-ioctl32.c     Hans Verkuil          2008-12-21 @117  		ret = file->f_op->unlocked_ioctl(file, cmd, arg);
92f45badbbaccd drivers/media/video/v4l2-compat-ioctl32.c     Hans Verkuil          2008-12-21  118  
92f45badbbaccd drivers/media/video/v4l2-compat-ioctl32.c     Hans Verkuil          2008-12-21  119  	return ret;
92f45badbbaccd drivers/media/video/v4l2-compat-ioctl32.c     Hans Verkuil          2008-12-21  120  }
92f45badbbaccd drivers/media/video/v4l2-compat-ioctl32.c     Hans Verkuil          2008-12-21  121  

:::::: The code at line 117 was first introduced by commit
:::::: 92f45badbbaccdbc1be25085292a1e258948e221 V4L/DVB (9932): v4l2-compat32: fix 32-64 compatibility module

:::::: TO: Hans Verkuil <hverkuil@xs4all.nl>
:::::: CC: Mauro Carvalho Chehab <mchehab@redhat.com>

---
0-DAY kernel test infrastructure                 Open Source Technology Center
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org Intel Corporation

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