linux-kernel - [kbusch:dma-register 4/4] drivers/nvme/host/pci.c:1812:7: warning: variable 'pages

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Message-ID: <202207200447.tQ5AF3SH-lkp@intel.com>
Date:   Wed, 20 Jul 2022 04:08:43 +0800
From:   kernel test robot <lkp@...el.com>
To:     Keith Busch <kbusch@...nel.org>
Cc:     llvm@...ts.linux.dev, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org
Subject: [kbusch:dma-register 4/4] drivers/nvme/host/pci.c:1812:7: warning:
 variable 'pages_per' set but not used

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/kbusch/linux.git dma-register
head:   9de6909fed20955193275bbf9c75ccc85553b7d8
commit: 9de6909fed20955193275bbf9c75ccc85553b7d8 [4/4] dma-prereg: add memory cleanup
config: arm-randconfig-r013-20220718 (https://download.01.org/0day-ci/archive/20220720/202207200447.tQ5AF3SH-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project fa0c7639e91fa1cd0cf2ff0445a1634a90fe850a)
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 arm cross compiling tool for clang build
        # apt-get install binutils-arm-linux-gnueabi
        # https://git.kernel.org/pub/scm/linux/kernel/git/kbusch/linux.git/commit/?id=9de6909fed20955193275bbf9c75ccc85553b7d8
        git remote add kbusch https://git.kernel.org/pub/scm/linux/kernel/git/kbusch/linux.git
        git fetch --no-tags kbusch dma-register
        git checkout 9de6909fed20955193275bbf9c75ccc85553b7d8
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash drivers/nvme/host/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

>> drivers/nvme/host/pci.c:1812:7: warning: variable 'pages_per' set but not used [-Wunused-but-set-variable]
                   int pages_per = nvme_pages;
                       ^
   1 warning generated.


vim +/pages_per +1812 drivers/nvme/host/pci.c

  1782	
  1783	#ifdef CONFIG_HAS_DMA
  1784	/*
  1785	 * Important: bvec must be describing a virtually contiguous buffer.
  1786	 */
  1787	static void *nvme_pci_dma_map(struct request_queue *q,
  1788				       struct bio_vec *bvec, int nr_vecs)
  1789	{
  1790		const int nvme_pages = 1 << (PAGE_SIZE - NVME_CTRL_PAGE_SIZE);
  1791		struct nvme_ns *ns = q->queuedata;
  1792		struct nvme_dev *dev = to_nvme_dev(ns->ctrl);
  1793		struct nvme_dma_mapping *mapping;
  1794		int i, j, k, size, ret = -ENOMEM;
  1795	
  1796		if (!nr_vecs)
  1797			return ERR_PTR(-EINVAL);
  1798	
  1799		mapping = kzalloc(sizeof(*mapping), GFP_KERNEL);
  1800		if (!mapping)
  1801			return ERR_PTR(-ENOMEM);
  1802	
  1803		mapping->nr_pages = nr_vecs * nvme_pages;
  1804		size = sizeof(*mapping->prps) * mapping->nr_pages;
  1805		mapping->prps = dma_alloc_coherent(dev->dev, size,
  1806					&mapping->prp_dma_addr, GFP_KERNEL);
  1807		if (!mapping->prps)
  1808			goto free_mapping;
  1809	
  1810		for (i = 0, k = 0; i < nr_vecs; i++) {
  1811			struct bio_vec *bv = bvec + i;
> 1812			int pages_per = nvme_pages;
  1813			dma_addr_t dma_addr;
  1814	
  1815			if (i == 0) {
  1816				mapping->offset = bv->bv_offset;
  1817				pages_per -= mapping->offset >> NVME_CTRL_PAGE_SHIFT;
  1818			} else if (bv->bv_offset) {
  1819				ret = -EINVAL;
  1820				goto err;
  1821			}
  1822	
  1823			dma_addr = dma_map_bvec(dev->dev, bv, 0, 0);
  1824			if (dma_mapping_error(dev->dev, dma_addr)) {
  1825				ret = -EIO;
  1826				goto err;
  1827			}
  1828	
  1829			for (j = 0; j < nvme_pages; j++)
  1830				mapping->prps[k++] = cpu_to_le64(dma_addr +
  1831							j * NVME_CTRL_PAGE_SIZE);
  1832		}
  1833	
  1834		get_device(dev->dev);
  1835		return mapping;
  1836	
  1837	err:
  1838		while (--i > 0) {
  1839			__u64 dma_addr = le64_to_cpu(mapping->prps[i]);
  1840	
  1841			dma_unmap_page(dev->dev, dma_addr,
  1842				       PAGE_SIZE - offset_in_page(dma_addr), 0);
  1843		}
  1844	
  1845		dma_free_coherent(dev->dev, size, (void *)mapping->prps,
  1846				  mapping->prp_dma_addr);
  1847	free_mapping:
  1848		kfree(mapping);
  1849		return ERR_PTR(ret);
  1850	}
  1851	

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp