Re: [PATCH 1/2] net: core: datagram.c: Fix use of assignment in if condition

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

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Hi Shubhankar,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on net-next/master]
[also build test ERROR on linus/master v5.12-rc2 next-20210311]
[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/Shubhankar-Kuranagatti/net-core-datagram-c-Fix-use-of-assignment-in-if-condition/20210311-184120
base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git 34bb975126419e86bc3b95e200dc41de6c6ca69c
config: x86_64-randconfig-r025-20210311 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 574a9dabc63ba1e7a04c08d4bde2eacd61b44ce1)
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 x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # https://github.com/0day-ci/linux/commit/89811231e3ec535f3e5188fb8578535e13c1f1ba
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Shubhankar-Kuranagatti/net-core-datagram-c-Fix-use-of-assignment-in-if-condition/20210311-184120
        git checkout 89811231e3ec535f3e5188fb8578535e13c1f1ba
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

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

All errors (new ones prefixed by >>):

>> net/core/datagram.c:430:14: error: expected ';' after expression
                   len -= copy
                              ^
                              ;
   net/core/datagram.c:443:22: error: expected ';' after expression
                   copy = end - offset
                                      ^
                                      ;
   net/core/datagram.c:457:15: error: expected ';' after expression
                           len -= copy
                                      ^
                                      ;
   net/core/datagram.c:477:15: error: expected ';' after expression
                           len -= copy
                                      ^
                                      ;
   net/core/datagram.c:591:15: error: expected ';' after expression
                           len -= copy
                                      ^
                                      ;
   5 errors generated.


vim +430 net/core/datagram.c

   406	
   407	INDIRECT_CALLABLE_DECLARE(static size_t simple_copy_to_iter(const void *addr,
   408							size_t bytes,
   409							void *data __always_unused,
   410							struct iov_iter *i));
   411	
   412	static int __skb_datagram_iter(const struct sk_buff *skb, int offset,
   413				       struct iov_iter *to, int len, bool fault_short,
   414				       size_t (*cb)(const void *, size_t, void *,
   415						    struct iov_iter *), void *data)
   416	{
   417		int start = skb_headlen(skb);
   418		int i, copy = start - offset, start_off = offset, n;
   419		struct sk_buff *frag_iter;
   420	
   421		/* Copy header. */
   422		if (copy > 0) {
   423			if (copy > len)
   424				copy = len;
   425			n = INDIRECT_CALL_1(cb, simple_copy_to_iter,
   426					    skb->data + offset, copy, data, to);
   427			offset += n;
   428			if (n != copy)
   429				goto short_copy;
 > 430			len -= copy
   431			if ((len) == 0)
   432				return 0;
   433		}
   434	
   435		/* Copy paged appendix. Hmm... why does this look so complicated? */
   436		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
   437			int end;
   438			const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
   439	
   440			WARN_ON(start > offset + len);
   441	
   442			end = start + skb_frag_size(frag);
   443			copy = end - offset
   444			if ((copy) > 0) {
   445				struct page *page = skb_frag_page(frag);
   446				u8 *vaddr = kmap(page);
   447	
   448				if (copy > len)
   449					copy = len;
   450				n = INDIRECT_CALL_1(cb, simple_copy_to_iter,
   451						vaddr + skb_frag_off(frag) + offset - start,
   452						copy, data, to);
   453				kunmap(page);
   454				offset += n;
   455				if (n != copy)
   456					goto short_copy;
   457				len -= copy
   458				if (!(len))
   459					return 0;
   460			}
   461			start = end;
   462		}
   463	
   464		skb_walk_frags(skb, frag_iter) {
   465			int end;
   466	
   467			WARN_ON(start > offset + len);
   468	
   469			end = start + frag_iter->len;
   470			copy = end - offset;
   471			if ((copy) > 0) {
   472				if (copy > len)
   473					copy = len;
   474				if (__skb_datagram_iter(frag_iter, offset - start,
   475							to, copy, fault_short, cb, data))
   476					goto fault;
   477				len -= copy
   478				if ((len) == 0)
   479					return 0;
   480				offset += copy;
   481			}
   482			start = end;
   483		}
   484		if (!len)
   485			return 0;
   486	
   487		/* This is not really a user copy fault, but rather someone
   488		 * gave us a bogus length on the skb.  We should probably
   489		 * print a warning here as it may indicate a kernel bug.
   490		 */
   491	
   492	fault:
   493		iov_iter_revert(to, offset - start_off);
   494		return -EFAULT;
   495	
   496	short_copy:
   497		if (fault_short || iov_iter_count(to))
   498			goto fault;
   499	
   500		return 0;
   501	}
   502	

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

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