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Message-ID: <24c282d8-f740-ddda-53f7-04eb8f5ae4dd@intel.com>
Date:   Wed, 9 Mar 2022 13:52:49 +0800
From:   kernel test robot <yujie.liu@...el.com>
To:     Jason Gunthorpe <jgg@...dia.com>
CC:     <llvm@...ts.linux.dev>, <kbuild-all@...ts.01.org>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
        Nicolin Chen <nicolinc@...dia.com>
Subject: [jgunthorpe:iommufd 10/12] drivers/iommu/iommufd/vfio_compat.c:358:3:
 warning: Value stored to 'rc' is never read
 [clang-analyzer-deadcode.DeadStores]

tree:   https://github.com/jgunthorpe/linux iommufd
head:   446626304259cf3deb4a4799b42a909bea0bc070
commit: 6df3783f55eb10f5583783566fd12646ef693568 [10/12] iommufd: vfio container FD ioctl compatibility
config: mips-randconfig-c004-20220227 (https://download.01.org/0day-ci/archive/20220301/202203010007.dMWQzNHZ-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project d271fc04d5b97b12e6b797c6067d3c96a8d7470e)
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
         # install mips cross compiling tool for clang build
         # apt-get install binutils-mips-linux-gnu
         # https://github.com/jgunthorpe/linux/commit/6df3783f55eb10f5583783566fd12646ef693568
         git remote add jgunthorpe https://github.com/jgunthorpe/linux
         git fetch --no-tags jgunthorpe iommufd
         git checkout 6df3783f55eb10f5583783566fd12646ef693568
         # save the config file to linux build tree
         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips clang-analyzer

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


clang-analyzer warnings: (new ones prefixed by >>)

 >> drivers/iommu/iommufd/vfio_compat.c:358:3: warning: Value stored to 'rc' is never read [clang-analyzer-deadcode.DeadStores]
                    rc = -EFAULT;
                    ^    ~~~~~~~

vim +/rc +358 drivers/iommu/iommufd/vfio_compat.c

6df3783f55eb10 Jason Gunthorpe 2021-12-15  291
6df3783f55eb10 Jason Gunthorpe 2021-12-15  292  static int iommufd_vfio_iommu_get_info(struct iommufd_ctx *ictx,
6df3783f55eb10 Jason Gunthorpe 2021-12-15  293  				       void __user *arg)
6df3783f55eb10 Jason Gunthorpe 2021-12-15  294  {
6df3783f55eb10 Jason Gunthorpe 2021-12-15  295  	typedef int (*fill_cap_fn)(struct iommufd_ioas *ioas,
6df3783f55eb10 Jason Gunthorpe 2021-12-15  296  				   struct vfio_info_cap_header __user *cur,
6df3783f55eb10 Jason Gunthorpe 2021-12-15  297  				   size_t avail);
6df3783f55eb10 Jason Gunthorpe 2021-12-15  298  	static const fill_cap_fn fill_fns[] = {
6df3783f55eb10 Jason Gunthorpe 2021-12-15  299  		iommufd_fill_cap_iova,
6df3783f55eb10 Jason Gunthorpe 2021-12-15  300  		iommufd_fill_cap_dma_avail,
6df3783f55eb10 Jason Gunthorpe 2021-12-15  301  	};
6df3783f55eb10 Jason Gunthorpe 2021-12-15  302  	size_t minsz = offsetofend(struct vfio_iommu_type1_info, iova_pgsizes);
6df3783f55eb10 Jason Gunthorpe 2021-12-15  303  	struct vfio_info_cap_header __user *last_cap = NULL;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  304  	struct vfio_iommu_type1_info info;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  305  	struct iommufd_ioas *ioas;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  306  	size_t total_cap_size;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  307  	int rc;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  308  	int i;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  309
6df3783f55eb10 Jason Gunthorpe 2021-12-15  310  	if (copy_from_user(&info, arg, minsz))
6df3783f55eb10 Jason Gunthorpe 2021-12-15  311  		return -EFAULT;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  312
6df3783f55eb10 Jason Gunthorpe 2021-12-15  313  	if (info.argsz < minsz)
6df3783f55eb10 Jason Gunthorpe 2021-12-15  314  		return -EINVAL;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  315  	minsz = min_t(size_t, info.argsz, sizeof(info));
6df3783f55eb10 Jason Gunthorpe 2021-12-15  316
6df3783f55eb10 Jason Gunthorpe 2021-12-15  317  	ioas = get_compat_ioas(ictx);
6df3783f55eb10 Jason Gunthorpe 2021-12-15  318  	if (IS_ERR(ioas))
6df3783f55eb10 Jason Gunthorpe 2021-12-15  319  		return PTR_ERR(ioas);
6df3783f55eb10 Jason Gunthorpe 2021-12-15  320
6df3783f55eb10 Jason Gunthorpe 2021-12-15  321  	down_read(&ioas->iopt.iova_rwsem);
6df3783f55eb10 Jason Gunthorpe 2021-12-15  322  	info.flags = VFIO_IOMMU_INFO_PGSIZES;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  323  	info.iova_pgsizes = iommufd_get_pagesizes(ioas);
6df3783f55eb10 Jason Gunthorpe 2021-12-15  324  	info.cap_offset = 0;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  325
6df3783f55eb10 Jason Gunthorpe 2021-12-15  326  	total_cap_size = sizeof(info);
6df3783f55eb10 Jason Gunthorpe 2021-12-15  327  	for (i = 0; i != ARRAY_SIZE(fill_fns); i++) {
6df3783f55eb10 Jason Gunthorpe 2021-12-15  328  		int cap_size;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  329
6df3783f55eb10 Jason Gunthorpe 2021-12-15  330  		if (info.argsz > total_cap_size)
6df3783f55eb10 Jason Gunthorpe 2021-12-15  331  			cap_size = fill_fns[i](ioas, arg + total_cap_size,
6df3783f55eb10 Jason Gunthorpe 2021-12-15  332  					       info.argsz - total_cap_size);
6df3783f55eb10 Jason Gunthorpe 2021-12-15  333  		else
6df3783f55eb10 Jason Gunthorpe 2021-12-15  334  			cap_size = fill_fns[i](ioas, NULL, 0);
6df3783f55eb10 Jason Gunthorpe 2021-12-15  335  		if (cap_size < 0) {
6df3783f55eb10 Jason Gunthorpe 2021-12-15  336  			rc = cap_size;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  337  			goto out_put;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  338  		}
6df3783f55eb10 Jason Gunthorpe 2021-12-15  339  		if (last_cap && info.argsz >= total_cap_size &&
6df3783f55eb10 Jason Gunthorpe 2021-12-15  340  		    put_user(total_cap_size, &last_cap->next)) {
6df3783f55eb10 Jason Gunthorpe 2021-12-15  341  			rc = -EFAULT;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  342  			goto out_put;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  343  		}
6df3783f55eb10 Jason Gunthorpe 2021-12-15  344  		last_cap = arg + total_cap_size;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  345  		total_cap_size += cap_size;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  346  	}
6df3783f55eb10 Jason Gunthorpe 2021-12-15  347
6df3783f55eb10 Jason Gunthorpe 2021-12-15  348  	/*
6df3783f55eb10 Jason Gunthorpe 2021-12-15  349  	 * If the user did not provide enough space then only some caps are
6df3783f55eb10 Jason Gunthorpe 2021-12-15  350  	 * returned and the argsz will be updated to the correct amount to get
6df3783f55eb10 Jason Gunthorpe 2021-12-15  351  	 * all caps.
6df3783f55eb10 Jason Gunthorpe 2021-12-15  352  	 */
6df3783f55eb10 Jason Gunthorpe 2021-12-15  353  	if (info.argsz >= total_cap_size)
6df3783f55eb10 Jason Gunthorpe 2021-12-15  354  		info.cap_offset = sizeof(info);
6df3783f55eb10 Jason Gunthorpe 2021-12-15  355  	info.argsz = total_cap_size;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  356  	info.flags |= VFIO_IOMMU_INFO_CAPS;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  357  	if (copy_to_user(arg, &info, minsz))
6df3783f55eb10 Jason Gunthorpe 2021-12-15 @358  		rc = -EFAULT;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  359  	rc = 0;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  360
6df3783f55eb10 Jason Gunthorpe 2021-12-15  361  out_put:
6df3783f55eb10 Jason Gunthorpe 2021-12-15  362  	up_read(&ioas->iopt.iova_rwsem);
6df3783f55eb10 Jason Gunthorpe 2021-12-15  363  	iommufd_put_object(&ioas->obj);
6df3783f55eb10 Jason Gunthorpe 2021-12-15  364  	return rc;
6df3783f55eb10 Jason Gunthorpe 2021-12-15  365  }
6df3783f55eb10 Jason Gunthorpe 2021-12-15  366

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

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