Hi Paolo,

I love your patch! Perhaps something to improve:

[auto build test WARNING on block/for-next]
[cannot apply to v5.11-rc5 next-20210125]
[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/Paolo-Valente/block-bfq-third-and-last-batch-of-fixes-and-improvements/20210127-090045
base:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git for-next
config: x86_64-randconfig-a003-20210126 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 74784a5aa47bb8967e5868831e359fa631abe465)
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/2d32d2f7e624f94a180d6a6acfeea65c0c511fe1
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Paolo-Valente/block-bfq-third-and-last-batch-of-fixes-and-improvements/20210127-090045
        git checkout 2d32d2f7e624f94a180d6a6acfeea65c0c511fe1
        # 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 >>):

>> block/bfq-iosched.c:5340:1: warning: no previous prototype for function 'bfq_do_early_stable_merge' [-Wmissing-prototypes]
   bfq_do_early_stable_merge(struct bfq_data *bfqd, struct bfq_queue *bfqq,
   ^
   block/bfq-iosched.c:5339:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   struct bfq_queue *
   ^
   static 
   1 warning generated.


vim +/bfq_do_early_stable_merge +5340 block/bfq-iosched.c

  5338	
  5339	struct bfq_queue *
> 5340	bfq_do_early_stable_merge(struct bfq_data *bfqd, struct bfq_queue *bfqq,
  5341				  struct bfq_io_cq *bic,
  5342				  struct bfq_queue *last_bfqq_created)
  5343	{
  5344		struct bfq_queue *new_bfqq =
  5345			bfq_setup_merge(bfqq, last_bfqq_created);
  5346	
  5347		if (!new_bfqq)
  5348			return bfqq;
  5349	
  5350		if (new_bfqq->bic)
  5351			new_bfqq->bic->stably_merged = true;
  5352		bic->stably_merged = true;
  5353	
  5354		/*
  5355		 * Reusing merge functions. This implies that
  5356		 * bfqq->bic must be set too, for
  5357		 * bfq_merge_bfqqs to correctly save bfqq's
  5358		 * state before killing it.
  5359		 */
  5360		bfqq->bic = bic;
  5361		bfq_merge_bfqqs(bfqd, bic, bfqq, new_bfqq);
  5362	
  5363		return new_bfqq;
  5364	}
  5365	

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