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Subject[bvanassche:configfs 1/3] fs/configfs/file.c:234:6: warning: variable 'written' is used uninitialized whenever 'if' condition is false
tree:   https://github.com/bvanassche/linux configfs
head: d039a111183e8b3aafba81b0bbc4bf620e79b818
commit: 314a1ff31221fcdf3d62e0142b4212d6410e4173 [1/3] configfs: Improve writing at a non-zero offset
config: x86_64-randconfig-r031-20210723 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 9625ca5b602616b2f5584e8a49ba93c52c141e40)
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/bvanassche/linux/commit/314a1ff31221fcdf3d62e0142b4212d6410e4173
git remote add bvanassche https://github.com/bvanassche/linux
git fetch --no-tags bvanassche configfs
git checkout 314a1ff31221fcdf3d62e0142b4212d6410e4173
# 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 warnings (new ones prefixed by >>):

>> fs/configfs/file.c:234:6: warning: variable 'written' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
if (len > 0)
^~~~~~~
fs/configfs/file.c:236:6: note: uninitialized use occurs here
if (written > 0)
^~~~~~~
fs/configfs/file.c:234:2: note: remove the 'if' if its condition is always true
if (len > 0)
^~~~~~~~~~~~
fs/configfs/file.c:230:22: note: initialize the variable 'written' to silence this warning
ssize_t len, written;
^
= 0
1 warning generated.


vim +234 fs/configfs/file.c

7063fbf2261194 Joel Becker 2005-12-15 217
7063fbf2261194 Joel Becker 2005-12-15 218
44b9a000df5cc1 Christoph Hellwig 2021-05-25 219 /*
7063fbf2261194 Joel Becker 2005-12-15 220 * There is no easy way for us to know if userspace is only doing a partial
44b9a000df5cc1 Christoph Hellwig 2021-05-25 221 * write, so we don't support them. We expect the entire buffer to come on the
44b9a000df5cc1 Christoph Hellwig 2021-05-25 222 * first write.
44b9a000df5cc1 Christoph Hellwig 2021-05-25 223 * Hint: if you're writing a value, first read the file, modify only the value
44b9a000df5cc1 Christoph Hellwig 2021-05-25 224 * you're changing, then write entire buffer back.
7063fbf2261194 Joel Becker 2005-12-15 225 */
7fe1e79b59ba02 Bart Van Assche 2021-05-25 226 static ssize_t configfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
7063fbf2261194 Joel Becker 2005-12-15 227 {
7fe1e79b59ba02 Bart Van Assche 2021-05-25 228 struct file *file = iocb->ki_filp;
7063fbf2261194 Joel Becker 2005-12-15 229 struct configfs_buffer *buffer = file->private_data;
314a1ff31221fc Bart Van Assche 2021-07-22 230 ssize_t len, written;
7063fbf2261194 Joel Becker 2005-12-15 231
6d748924b753d6 Johannes Berg 2007-06-22 232 mutex_lock(&buffer->mutex);
420405ecde061f Bart Van Assche 2021-07-13 233 len = fill_write_buffer(buffer, iocb->ki_pos, from);
3d0f89bb169482 Joel Becker 2006-01-25 @234 if (len > 0)
314a1ff31221fc Bart Van Assche 2021-07-22 235 written = flush_write_buffer(file, buffer, iocb->ki_pos + len);
314a1ff31221fc Bart Van Assche 2021-07-22 236 if (written > 0)
7fe1e79b59ba02 Bart Van Assche 2021-05-25 237 iocb->ki_pos += len;
6d748924b753d6 Johannes Berg 2007-06-22 238 mutex_unlock(&buffer->mutex);
3d0f89bb169482 Joel Becker 2006-01-25 239 return len;
7063fbf2261194 Joel Becker 2005-12-15 240 }
7063fbf2261194 Joel Becker 2005-12-15 241

:::::: The code at line 234 was first introduced by commit
:::::: 3d0f89bb169482d26d5aa4e82e763077e7e9bc4d configfs: Add permission and ownership to configfs objects.

:::::: TO: Joel Becker <joel.becker@oracle.com>
:::::: CC: Mark Fasheh <mark.fasheh@oracle.com>

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