Hi Jens,

I love your patch! Yet something to improve:

[auto build test ERROR on axboe-block/for-next]
[cannot apply to linus/master v5.15-rc6 next-20211022]
[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/Jens-Axboe/Various-block-layer-optimizations/20211017-093822
base:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git for-next
config: um-x86_64_defconfig (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/6ed4540d0461ab59f1dc96a0b448eb12c3446182
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Jens-Axboe/Various-block-layer-optimizations/20211017-093822
        git checkout 6ed4540d0461ab59f1dc96a0b448eb12c3446182
        # save the attached .config to linux build tree
        make W=1 ARCH=um SUBARCH=x86_64

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

All error/warnings (new ones prefixed by >>):

   block/blk-core.c: In function 'blk_flush_plug_list':
>> block/blk-core.c:1636:7: error: implicit declaration of function 'rq_list_empty'; did you mean 'bio_list_empty'? [-Werror=implicit-function-declaration]
    1636 |  if (!rq_list_empty(plug->mq_list))
         |       ^~~~~~~~~~~~~
         |       bio_list_empty
   cc1: some warnings being treated as errors
--
   block/blk-merge.c: In function 'blk_attempt_plug_merge':
>> block/blk-merge.c:1094:15: error: implicit declaration of function 'rq_list_empty'; did you mean 'bio_list_empty'? [-Werror=implicit-function-declaration]
    1094 |  if (!plug || rq_list_empty(plug->mq_list))
         |               ^~~~~~~~~~~~~
         |               bio_list_empty
>> block/blk-merge.c:1098:7: error: implicit declaration of function 'rq_list_peek'; did you mean 'bio_list_peek'? [-Werror=implicit-function-declaration]
    1098 |  rq = rq_list_peek(&plug->mq_list);
         |       ^~~~~~~~~~~~
         |       bio_list_peek
>> block/blk-merge.c:1098:5: warning: assignment to 'struct request *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
    1098 |  rq = rq_list_peek(&plug->mq_list);
         |     ^
   cc1: some warnings being treated as errors
--
   block/blk-mq.c: In function 'blk_mq_plug_issue_direct':
>> block/blk-mq.c:2134:10: error: implicit declaration of function 'rq_list_empty'; did you mean 'bio_list_empty'? [-Werror=implicit-function-declaration]
    2134 |  while (!rq_list_empty(plug->mq_list)) {
         |          ^~~~~~~~~~~~~
         |          bio_list_empty
>> block/blk-mq.c:2138:8: error: implicit declaration of function 'rq_list_pop'; did you mean 'bio_list_pop'? [-Werror=implicit-function-declaration]
    2138 |   rq = rq_list_pop(&plug->mq_list);
         |        ^~~~~~~~~~~
         |        bio_list_pop
>> block/blk-mq.c:2138:6: warning: assignment to 'struct request *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
    2138 |   rq = rq_list_pop(&plug->mq_list);
         |      ^
   block/blk-mq.c: In function 'blk_mq_flush_plug_list':
   block/blk-mq.c:2197:6: warning: assignment to 'struct request *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
    2197 |   rq = rq_list_pop(&plug->mq_list);
         |      ^
   block/blk-mq.c: In function 'blk_add_rq_to_plug':
>> block/blk-mq.c:2402:25: error: implicit declaration of function 'rq_list_peek'; did you mean 'bio_list_peek'? [-Werror=implicit-function-declaration]
    2402 |   struct request *nxt = rq_list_peek(&plug->mq_list);
         |                         ^~~~~~~~~~~~
         |                         bio_list_peek
>> block/blk-mq.c:2402:25: warning: initialization of 'struct request *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
>> block/blk-mq.c:2410:2: error: implicit declaration of function 'rq_list_add'; did you mean 'rq_qos_add'? [-Werror=implicit-function-declaration]
    2410 |  rq_list_add(&plug->mq_list, rq);
         |  ^~~~~~~~~~~
         |  rq_qos_add
   block/blk-mq.c: In function 'blk_mq_submit_bio':
   block/blk-mq.c:2526:8: warning: assignment to 'struct request *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
    2526 |    tmp = rq_list_peek(&plug->mq_list);
         |        ^
   block/blk-mq.c:2551:13: warning: assignment to 'struct request *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
    2551 |    first_rq = rq_list_pop(&plug->mq_list);
         |             ^
   cc1: some warnings being treated as errors


vim +1636 block/blk-core.c

  1631	
  1632	void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
  1633	{
  1634		flush_plug_callbacks(plug, from_schedule);
  1635	
> 1636		if (!rq_list_empty(plug->mq_list))
  1637			blk_mq_flush_plug_list(plug, from_schedule);
  1638		if (unlikely(!from_schedule && plug->cached_rq))
  1639			blk_mq_free_plug_rqs(plug);
  1640	}
  1641	

---
0-DAY CI Kernel Test Service, Intel Corporation
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