[dhowells-fs:fscache-iter 23/33] fs/fscache/read_helper.c:258:10: warning: 'x_flags' may be used uninitialized in this function

[dhowells-fs:fscache-iter 23/33] fs/fscache/read_helper.c:258:10: warning: 'x_flags' may be used uninitialized in this function

[kbuild test robot]

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git fscache-iter
head:   f62d2e3b55357b54ea4a541e85200ecdccfce7b4
commit: b546e3179314dd9f56dd09047dfdaf93a2baada3 [23/33] fscache: Add read helper
config: x86_64-randconfig-a002-201945 (attached as .config)
compiler: gcc-7 (Debian 7.4.0-14) 7.4.0
reproduce:
        git checkout b546e3179314dd9f56dd09047dfdaf93a2baada3
        # 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 >>):

   fs/fscache/read_helper.c: In function 'fscache_read_helper':
>> fs/fscache/read_helper.c:258:10: warning: 'x_flags' may be used uninitialized in this function [-Wmaybe-uninitialized]
     x_flags |= fscache_shape_extent(req->io_handle, extent, i_size, false);
             ^~
>> fs/fscache/read_helper.c:479:9: warning: 'ret' may be used uninitialized in this function [-Wmaybe-uninitialized]
     return ret;
            ^~~

vim +/x_flags +258 fs/fscache/read_helper.c

   209	
   210	/**
   211	 * fscache_read_helper - Helper to manage a read request
   212	 * @req: The initialised request structure to use
   213	 * @extent: The extent of the pages to access
   214	 * @requested_page: Singular page to include
   215	 * @pages: Unattached pages to include (readpages)
   216	 * @type: FSCACHE_READ_*
   217	 * @aop_flags: AOP_FLAG_*
   218	 *
   219	 * Read a sequence of pages appropriately sized for an fscache allocation
   220	 * block.  Pages are added at both ends and to fill in the gaps as appropriate
   221	 * to make it the right size.
   222	 *
   223	 * req->mapping should indicate the mapping to which the pages will be attached.
   224	 *
   225	 * The operations pointed to by req->ops will be used to issue or reissue a
   226	 * read against the server in case the cache is unavailable, incomplete or
   227	 * generates an error.  req->iter will be set up to point to the iterator
   228	 * representing the buffer to be filled in.
   229	 */
   230	int fscache_read_helper(struct fscache_io_request *req,
   231				struct fscache_extent *extent,
   232				struct page **requested_page,
   233				struct list_head *pages,
   234				enum fscache_read_type type,
   235				unsigned int aop_flags)
   236	{
   237		struct address_space *mapping = req->mapping;
   238		struct page *page;
   239		unsigned char x_flags;
   240		pgoff_t eof, cursor, start, first_index, trailer = ULONG_MAX;
   241		loff_t i_size;
   242		int ret;
   243	
   244		first_index = extent->start;
   245		_enter("{%lx,%lx}", first_index, extent->limit);
   246	
   247		ASSERTIFCMP(requested_page && *requested_page,
   248			    (*requested_page)->index, ==, first_index);
   249		ASSERTIF(type == FSCACHE_READ_LOCKED_PAGE ||
   250			 type == FSCACHE_READ_FOR_WRITE,
   251			 pages == NULL);
   252		ASSERTIFCMP(pages && !list_empty(pages),
   253			    first_index, ==, lru_to_page(pages)->index);
   254	
   255		i_size = i_size_read(mapping->host);
   256		eof = (i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
   257	
 > 258		x_flags |= fscache_shape_extent(req->io_handle, extent, i_size, false);

---
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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