Hi Liu,

[FYI, it's a private test report for your RFC patch.]
[auto build test WARNING on hch-configfs/for-next]
[cannot apply to joro-iommu/next awilliam-vfio/next linus/master v5.15-rc1 next-20210917]
[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/Liu-Yi-L/Introduce-dev-iommu-for-userspace-I-O-address-space-management/20210919-144631
base:   git://git.infradead.org/users/hch/configfs.git for-next
config: i386-randconfig-a016-20210919 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project c8b3d7d6d6de37af68b2f379d0e37304f78e115f)
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/262b8a31d0b9bbcb24f7fc2eed5e7ac849265047
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Liu-Yi-L/Introduce-dev-iommu-for-userspace-I-O-address-space-management/20210919-144631
        git checkout 262b8a31d0b9bbcb24f7fc2eed5e7ac849265047
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=i386 

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/iommu/iommufd/iommufd.c:205:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
           if (refcount_read(&ioas->refs) > 1) {
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/iommu/iommufd/iommufd.c:213:9: note: uninitialized use occurs here
           return ret;
                  ^~~
   drivers/iommu/iommufd/iommufd.c:205:2: note: remove the 'if' if its condition is always true
           if (refcount_read(&ioas->refs) > 1) {
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/iommu/iommufd/iommufd.c:189:17: note: initialize the variable 'ret' to silence this warning
           int ioasid, ret;
                          ^
                           = 0
   drivers/iommu/iommufd/iommufd.c:369:7: warning: variable 'ret' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
                   if (idev->dev == dev || idev->dev_cookie == dev_cookie) {
                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/iommu/iommufd/iommufd.c:409:17: note: uninitialized use occurs here
           return ERR_PTR(ret);
                          ^~~
   drivers/iommu/iommufd/iommufd.c:369:3: note: remove the 'if' if its condition is always false
                   if (idev->dev == dev || idev->dev_cookie == dev_cookie) {
                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/iommu/iommufd/iommufd.c:369:7: warning: variable 'ret' is used uninitialized whenever '||' condition is true [-Wsometimes-uninitialized]
                   if (idev->dev == dev || idev->dev_cookie == dev_cookie) {
                       ^~~~~~~~~~~~~~~~
   drivers/iommu/iommufd/iommufd.c:409:17: note: uninitialized use occurs here
           return ERR_PTR(ret);
                          ^~~
   drivers/iommu/iommufd/iommufd.c:369:7: note: remove the '||' if its condition is always false
                   if (idev->dev == dev || idev->dev_cookie == dev_cookie) {
                       ^~~~~~~~~~~~~~~~~~~
   drivers/iommu/iommufd/iommufd.c:359:9: note: initialize the variable 'ret' to silence this warning
           int ret;
                  ^
                   = 0
   3 warnings generated.

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for IOMMUFD
   Depends on IOMMU_SUPPORT
   Selected by
   - VFIO_PCI && VFIO && PCI && EVENTFD && MMU


vim +205 drivers/iommu/iommufd/iommufd.c

   185	
   186	static int iommufd_ioasid_free(struct iommufd_ctx *ictx, unsigned long arg)
   187	{
   188		struct iommufd_ioas *ioas = NULL;
   189		int ioasid, ret;
   190	
   191		if (copy_from_user(&ioasid, (void __user *)arg, sizeof(ioasid)))
   192			return -EFAULT;
   193	
   194		if (ioasid < 0)
   195			return -EINVAL;
   196	
   197		mutex_lock(&ictx->lock);
   198		ioas = xa_load(&ictx->ioasid_xa, ioasid);
   199		if (IS_ERR(ioas)) {
   200			ret = -EINVAL;
   201			goto out_unlock;
   202		}
   203	
   204		/* Disallow free if refcount is not 1 */
 > 205		if (refcount_read(&ioas->refs) > 1) {
   206			ret = -EBUSY;
   207			goto out_unlock;
   208		}
   209	
   210		ioas_put_locked(ioas);
   211	out_unlock:
   212		mutex_unlock(&ictx->lock);
   213		return ret;
   214	};
   215	

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