Re: [RESEND PATCH 3/5] loop: add helper loop_queue_work_prep

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

Hi Ming,

kernel test robot noticed the following build warnings:

[auto build test WARNING on axboe-block/for-next]
[also build test WARNING on linus/master v6.14-rc5 next-20250307]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Ming-Lei/loop-remove-rw-parameter-from-lo_rw_aio/20250309-002548
base:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git for-next
patch link:    https://lore.kernel.org/r/20250308162312.1640828-4-ming.lei%40redhat.com
patch subject: [RESEND PATCH 3/5] loop: add helper loop_queue_work_prep
config: arc-randconfig-001-20250309 (https://download.01.org/0day-ci/archive/20250309/202503091413.vbFFy32o-lkp@intel.com/config)
compiler: arceb-elf-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250309/202503091413.vbFFy32o-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202503091413.vbFFy32o-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/block/loop.c: In function 'loop_queue_work_prep':
>> drivers/block/loop.c:862:25: warning: unused variable 'rq' [-Wunused-variable]
     862 |         struct request *rq = blk_mq_rq_from_pdu(cmd);
         |                         ^~


vim +/rq +862 drivers/block/loop.c

   859	
   860	static void loop_queue_work_prep(struct loop_cmd *cmd)
   861	{
 > 862		struct request *rq = blk_mq_rq_from_pdu(cmd);
   863	
   864		/* always use the first bio's css */
   865		cmd->blkcg_css = NULL;
   866		cmd->memcg_css = NULL;
   867	#ifdef CONFIG_BLK_CGROUP
   868		if (rq->bio) {
   869			cmd->blkcg_css = bio_blkcg_css(rq->bio);
   870	#ifdef CONFIG_MEMCG
   871			if (cmd->blkcg_css) {
   872				cmd->memcg_css =
   873					cgroup_get_e_css(cmd->blkcg_css->cgroup,
   874							&memory_cgrp_subsys);
   875			}
   876	#endif
   877		}
   878	#endif
   879	}
   880	

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