Re: [RFC PATCH 1/4] workqueue: support pausing ordered workqueues

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

Hi Johannes,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build warnings:

[auto build test WARNING on wireless-next/main]
[also build test WARNING on wireless/main tj-wq/for-next linus/master v6.4-rc1 next-20230510]
[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/Johannes-Berg/workqueue-support-pausing-ordered-workqueues/20230511-000621
base:   https://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless-next.git main
patch link:    https://lore.kernel.org/r/20230510175846.85cb30389c22.Ia49f779e11c2814294ea7f8bb29f825fb840be51%40changeid
patch subject: [RFC PATCH 1/4] workqueue: support pausing ordered workqueues
config: powerpc-allnoconfig (https://download.01.org/0day-ci/archive/20230511/202305110243.2OKGEFEb-lkp@intel.com/config)
compiler: powerpc-linux-gcc (GCC) 12.1.0
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
        # https://github.com/intel-lab-lkp/linux/commit/2053f0ebc109c7389b2e04f03af65dac874ee632
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Johannes-Berg/workqueue-support-pausing-ordered-workqueues/20230511-000621
        git checkout 2053f0ebc109c7389b2e04f03af65dac874ee632
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=powerpc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202305110243.2OKGEFEb-lkp@intel.com/

All warnings (new ones prefixed by >>):

   kernel/workqueue.c: In function 'pwq_adjust_max_active':
>> kernel/workqueue.c:3866:13: warning: variable 'new_max_active' set but not used [-Wunused-but-set-variable]
    3866 |         int new_max_active;
         |             ^~~~~~~~~~~~~~


vim +/new_max_active +3866 kernel/workqueue.c

  3852	
  3853	/**
  3854	 * pwq_adjust_max_active - update a pwq's max_active to the current setting
  3855	 * @pwq: target pool_workqueue
  3856	 *
  3857	 * If @pwq isn't freezing, set @pwq->max_active to the associated
  3858	 * workqueue's saved_max_active and activate inactive work items
  3859	 * accordingly.  If @pwq is freezing, clear @pwq->max_active to zero.
  3860	 */
  3861	static void pwq_adjust_max_active(struct pool_workqueue *pwq)
  3862	{
  3863		struct workqueue_struct *wq = pwq->wq;
  3864		bool freezable = wq->flags & WQ_FREEZABLE;
  3865		unsigned long flags;
> 3866		int new_max_active;
  3867	
  3868		/* for @wq->saved_max_active and @wq->flags */
  3869		lockdep_assert_held(&wq->mutex);
  3870	
  3871		if (wq->flags & __WQ_PAUSED)
  3872			new_max_active = 0;
  3873		else
  3874			new_max_active = wq->saved_max_active;
  3875	
  3876		/* fast exit for non-freezable wqs */
  3877		if (!freezable && pwq->max_active == wq->saved_max_active)
  3878			return;
  3879	
  3880		/* this function can be called during early boot w/ irq disabled */
  3881		raw_spin_lock_irqsave(&pwq->pool->lock, flags);
  3882	
  3883		/*
  3884		 * During [un]freezing, the caller is responsible for ensuring that
  3885		 * this function is called at least once after @workqueue_freezing
  3886		 * is updated and visible.
  3887		 */
  3888		if (!freezable || !workqueue_freezing) {
  3889			bool kick = false;
  3890	
  3891			pwq->max_active = wq->saved_max_active;
  3892	
  3893			while (!list_empty(&pwq->inactive_works) &&
  3894			       pwq->nr_active < pwq->max_active) {
  3895				pwq_activate_first_inactive(pwq);
  3896				kick = true;
  3897			}
  3898	
  3899			/*
  3900			 * Need to kick a worker after thawed or an unbound wq's
  3901			 * max_active is bumped. In realtime scenarios, always kicking a
  3902			 * worker will cause interference on the isolated cpu cores, so
  3903			 * let's kick iff work items were activated.
  3904			 */
  3905			if (kick)
  3906				wake_up_worker(pwq->pool);
  3907		} else {
  3908			pwq->max_active = 0;
  3909		}
  3910	
  3911		raw_spin_unlock_irqrestore(&pwq->pool->lock, flags);
  3912	}
  3913	

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