Re: [PATCH] kthread: Teach lockdep about kthread_flush_work() dependencies

Re: [PATCH] kthread: Teach lockdep about kthread_flush_work() dependencies

[kernel test robot]

Hi David,

kernel test robot noticed the following build warnings:

[auto build test WARNING on chrome-platform/for-next]
[also build test WARNING on chrome-platform/for-firmware-next linus/master v7.3 next-20261019]
[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/David-Woodhouse/kthread-Teach-lockdep-about-kthread_flush_work-dependencies/20261020-160400
base:   https://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux.git for-next
patch link:    https://lore.kernel.org/r/6dee36e290c2a3b85dcd7cdba2cab72fe57b25c4.camel%40infradead.org
patch subject: [PATCH] kthread: Teach lockdep about kthread_flush_work() dependencies
config: s390-defconfig (https://download.01.org/0day-ci/archive/20261021/202610211757.UM0pu0Gh-lkp@intel.com/config)
compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20261021/202610211757.UM0pu0Gh-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/202610211757.UM0pu0Gh-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/vdpa/vdpa_sim/vdpa_sim.c:71:2: warning: unused variable '__work_key' [-Wunused-variable]
      71 |         kthread_init_work(work, vdpasim_mm_work_fn);
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/kthread.h:219:32: note: expanded from macro 'kthread_init_work'
     219 |                 static struct lock_class_key __work_key;                \
         |                                              ^~~~~~~~~~
   drivers/vdpa/vdpa_sim/vdpa_sim.c:234:2: warning: unused variable '__work_key' [-Wunused-variable]
     234 |         kthread_init_work(&vdpasim->work, vdpasim_work_fn);
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/kthread.h:219:32: note: expanded from macro 'kthread_init_work'
     219 |                 static struct lock_class_key __work_key;                \
         |                                              ^~~~~~~~~~
   2 warnings generated.


vim +/__work_key +71 drivers/vdpa/vdpa_sim/vdpa_sim.c

4bb94d2de2fa90a Stefano Garzarella 2023-04-04  65  
4bb94d2de2fa90a Stefano Garzarella 2023-04-04  66  static void vdpasim_worker_change_mm_sync(struct vdpasim *vdpasim,
4bb94d2de2fa90a Stefano Garzarella 2023-04-04  67  					  struct vdpasim_mm_work *mm_work)
4bb94d2de2fa90a Stefano Garzarella 2023-04-04  68  {
4bb94d2de2fa90a Stefano Garzarella 2023-04-04  69  	struct kthread_work *work = &mm_work->work;
4bb94d2de2fa90a Stefano Garzarella 2023-04-04  70  
4bb94d2de2fa90a Stefano Garzarella 2023-04-04 @71  	kthread_init_work(work, vdpasim_mm_work_fn);
4bb94d2de2fa90a Stefano Garzarella 2023-04-04  72  	kthread_queue_work(vdpasim->worker, work);
4bb94d2de2fa90a Stefano Garzarella 2023-04-04  73  
4bb94d2de2fa90a Stefano Garzarella 2023-04-04  74  	kthread_flush_work(work);
4bb94d2de2fa90a Stefano Garzarella 2023-04-04  75  }
4bb94d2de2fa90a Stefano Garzarella 2023-04-04  76  

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