Re: [PATCH v2] tpm: Rework open/close/shutdown to avoid races

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

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Hi Sergey,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on char-misc/char-misc-testing]
[also build test WARNING on linux/master linus/master v5.10 next-20201215]
[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]

url:    https://github.com/0day-ci/linux/commits/Sergey-Temerkhanov/tpm-Rework-open-close-shutdown-to-avoid-races/20201215-214304
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git 93f998879cd95b3e4f2836e7b17d6d5ae035cf90
config: m68k-randconfig-r012-20201215 (attached as .config)
compiler: m68k-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/b1f6f05f320b6b609ff70567a701e12504783b02
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Sergey-Temerkhanov/tpm-Rework-open-close-shutdown-to-avoid-races/20201215-214304
        git checkout b1f6f05f320b6b609ff70567a701e12504783b02
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=m68k 

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

All warnings (new ones prefixed by >>):

   drivers/char/tpm/tpm-dev.c: In function 'tpm_open':
>> drivers/char/tpm/tpm-dev.c:22:6: warning: variable 'ret' set but not used [-Wunused-but-set-variable]
      22 |  int ret = 0;
         |      ^~~

vim +/ret +22 drivers/char/tpm/tpm-dev.c

    17	
    18	static int tpm_open(struct inode *inode, struct file *file)
    19	{
    20		struct tpm_chip *chip;
    21		struct file_priv *priv;
  > 22		int ret = 0;
    23	
    24		chip = container_of(inode->i_cdev, struct tpm_chip, cdev);
    25	
    26		/* It's assured that the chip will be opened just once,
    27		 * by the check of the chip reference count.
    28		 */
    29		if (atomic_fetch_inc(&chip->refcount)) {
    30			dev_dbg(&chip->dev, "Another process owns this TPM\n");
    31			ret = -EBUSY;
    32			goto out;
    33		}
    34	
    35		priv = kzalloc(sizeof(*priv), GFP_KERNEL);
    36		if (priv == NULL) {
    37			ret = -ENOMEM;
    38			goto out;
    39		}
    40	
    41		tpm_common_open(file, chip, priv, NULL);
    42	
    43		return 0;
    44	
    45	 out:
    46		atomic_dec(&chip->refcount);
    47		wake_up_all(&chip->waitq);
    48		return -ENOMEM;
    49	}
    50	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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