linux-kernel - block/blk-iocost.c:1183:6: warning: variable 'last

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Message-ID: <202401102335.GiWdeIo9-lkp@intel.com>
Date: Wed, 10 Jan 2024 23:19:04 +0800
From: kernel test robot <lkp@...el.com>
To: Tejun Heo <tj@...nel.org>
Cc: llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev,
	linux-kernel@...r.kernel.org, Jens Axboe <axboe@...nel.dk>
Subject: block/blk-iocost.c:1183:6: warning: variable 'last_period' set but
 not used

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   ab27740f76654ed58dd32ac0ba0031c18a6dea3b
commit: ac33e91e2daca40fcad66c68712276da7b40f169 blk-iocost: implement vtime loss compensation
date:   3 years, 4 months ago
config: x86_64-buildonly-randconfig-001-20240107 (https://download.01.org/0day-ci/archive/20240110/202401102335.GiWdeIo9-lkp@intel.com/config)
compiler: ClangBuiltLinux clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240110/202401102335.GiWdeIo9-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@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202401102335.GiWdeIo9-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> block/blk-iocost.c:1183:6: warning: variable 'last_period' set but not used [-Wunused-but-set-variable]
    1183 |         u64 last_period, cur_period;
         |             ^
   1 warning generated.


vim +/last_period +1183 block/blk-iocost.c

  1179	
  1180	static bool iocg_activate(struct ioc_gq *iocg, struct ioc_now *now)
  1181	{
  1182		struct ioc *ioc = iocg->ioc;
> 1183		u64 last_period, cur_period;
  1184		u64 vtime, vtarget;
  1185		int i;
  1186	
  1187		/*
  1188		 * If seem to be already active, just update the stamp to tell the
  1189		 * timer that we're still active.  We don't mind occassional races.
  1190		 */
  1191		if (!list_empty(&iocg->active_list)) {
  1192			ioc_now(ioc, now);
  1193			cur_period = atomic64_read(&ioc->cur_period);
  1194			if (atomic64_read(&iocg->active_period) != cur_period)
  1195				atomic64_set(&iocg->active_period, cur_period);
  1196			return true;
  1197		}
  1198	
  1199		/* racy check on internal node IOs, treat as root level IOs */
  1200		if (iocg->child_active_sum)
  1201			return false;
  1202	
  1203		spin_lock_irq(&ioc->lock);
  1204	
  1205		ioc_now(ioc, now);
  1206	
  1207		/* update period */
  1208		cur_period = atomic64_read(&ioc->cur_period);
  1209		last_period = atomic64_read(&iocg->active_period);
  1210		atomic64_set(&iocg->active_period, cur_period);
  1211	
  1212		/* already activated or breaking leaf-only constraint? */
  1213		if (!list_empty(&iocg->active_list))
  1214			goto succeed_unlock;
  1215		for (i = iocg->level - 1; i > 0; i--)
  1216			if (!list_empty(&iocg->ancestors[i]->active_list))
  1217				goto fail_unlock;
  1218	
  1219		if (iocg->child_active_sum)
  1220			goto fail_unlock;
  1221	
  1222		/*
  1223		 * Always start with the target budget. On deactivation, we throw away
  1224		 * anything above it.
  1225		 */
  1226		vtarget = now->vnow - ioc->margins.target;
  1227		vtime = atomic64_read(&iocg->vtime);
  1228	
  1229		atomic64_add(vtarget - vtime, &iocg->vtime);
  1230		atomic64_add(vtarget - vtime, &iocg->done_vtime);
  1231		vtime = vtarget;
  1232	
  1233		/*
  1234		 * Activate, propagate weight and start period timer if not
  1235		 * running.  Reset hweight_gen to avoid accidental match from
  1236		 * wrapping.
  1237		 */
  1238		iocg->hweight_gen = atomic_read(&ioc->hweight_gen) - 1;
  1239		list_add(&iocg->active_list, &ioc->active_iocgs);
  1240	
  1241		propagate_weights(iocg, iocg->weight,
  1242				  iocg->last_inuse ?: iocg->weight, true, now);
  1243	
  1244		TRACE_IOCG_PATH(iocg_activate, iocg, now,
  1245				last_period, cur_period, vtime);
  1246	
  1247		iocg->activated_at = now->now;
  1248	
  1249		if (ioc->running == IOC_IDLE) {
  1250			ioc->running = IOC_RUNNING;
  1251			ioc->debt_busy_at = now->now;
  1252			ioc_start_period(ioc, now);
  1253		}
  1254	
  1255	succeed_unlock:
  1256		spin_unlock_irq(&ioc->lock);
  1257		return true;
  1258	
  1259	fail_unlock:
  1260		spin_unlock_irq(&ioc->lock);
  1261		return false;
  1262	}
  1263	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki