linux-kernel - kernel/sched/core.c:1361:21: warning: 'uclamp

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Message-ID: <202410060258.bPl2ZoUo-lkp@intel.com>
Date: Sun, 6 Oct 2024 02:58:42 +0800
From: kernel test robot <lkp@...el.com>
To: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>
Subject: kernel/sched/core.c:1361:21: warning: 'uclamp_mutex' defined but not
 used

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   27cc6fdf720183dce1dbd293483ec5a9cb6b595e
commit: d2d6422f8bd17c6bb205133e290625a564194496 x86: Allow to enable PREEMPT_RT.
date:   3 weeks ago
config: x86_64-buildonly-randconfig-002-20241006 (https://download.01.org/0day-ci/archive/20241006/202410060258.bPl2ZoUo-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241006/202410060258.bPl2ZoUo-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/202410060258.bPl2ZoUo-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from include/linux/seqlock.h:19,
                    from include/linux/dcache.h:11,
                    from include/linux/fs.h:8,
                    from include/linux/highmem.h:5,
                    from kernel/sched/core.c:10:
>> kernel/sched/core.c:1361:21: warning: 'uclamp_mutex' defined but not used [-Wunused-variable]
    1361 | static DEFINE_MUTEX(uclamp_mutex);
         |                     ^~~~~~~~~~~~
   include/linux/mutex.h:101:22: note: in definition of macro 'DEFINE_MUTEX'
     101 |         struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
         |                      ^~~~~~~~~


vim +/uclamp_mutex +1361 kernel/sched/core.c

71f8bd4600521f kernel/sched.c      Ingo Molnar     2007-07-09  1349  
69842cba9ace84 kernel/sched/core.c Patrick Bellasi 2019-06-21  1350  #ifdef CONFIG_UCLAMP_TASK
2480c093130f64 kernel/sched/core.c Patrick Bellasi 2019-08-22  1351  /*
2480c093130f64 kernel/sched/core.c Patrick Bellasi 2019-08-22  1352   * Serializes updates of utilization clamp values
2480c093130f64 kernel/sched/core.c Patrick Bellasi 2019-08-22  1353   *
2480c093130f64 kernel/sched/core.c Patrick Bellasi 2019-08-22  1354   * The (slow-path) user-space triggers utilization clamp value updates which
2480c093130f64 kernel/sched/core.c Patrick Bellasi 2019-08-22  1355   * can require updates on (fast-path) scheduler's data structures used to
2480c093130f64 kernel/sched/core.c Patrick Bellasi 2019-08-22  1356   * support enqueue/dequeue operations.
2480c093130f64 kernel/sched/core.c Patrick Bellasi 2019-08-22  1357   * While the per-CPU rq lock protects fast-path update operations, user-space
2480c093130f64 kernel/sched/core.c Patrick Bellasi 2019-08-22  1358   * requests are serialized using a mutex to reduce the risk of conflicting
2480c093130f64 kernel/sched/core.c Patrick Bellasi 2019-08-22  1359   * updates or API abuses.
2480c093130f64 kernel/sched/core.c Patrick Bellasi 2019-08-22  1360   */
2480c093130f64 kernel/sched/core.c Patrick Bellasi 2019-08-22 @1361  static DEFINE_MUTEX(uclamp_mutex);
2480c093130f64 kernel/sched/core.c Patrick Bellasi 2019-08-22  1362  

:::::: The code at line 1361 was first introduced by commit
:::::: 2480c093130f64ac3a410504fa8b3db1fc4b87ce sched/uclamp: Extend CPU's cgroup controller

:::::: TO: Patrick Bellasi <patrick.bellasi@....com>
:::::: CC: Ingo Molnar <mingo@...nel.org>

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https://github.com/intel/lkp-tests/wiki