kernel/task_work.c:73: warning: Function parameter or member 'data' not described in 'task_work_cancel_match'

kernel/task_work.c:73: warning: Function parameter or member 'data' not described in 'task_work_cancel_match'

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   0bb80ecc33a8fb5a682236443c1e740d5c917d1d
commit: c7aab1a7c52b82d9afd7e03c398eb03dc2aa0507 task_work: add helper for more targeted task_work canceling
date:   2 years, 5 months ago
config: openrisc-allnoconfig (https://download.01.org/0day-ci/archive/20230912/202309120307.zis3yQGe-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 12.3.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230912/202309120307.zis3yQGe-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/202309120307.zis3yQGe-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/task_work.c:73: warning: Function parameter or member 'data' not described in 'task_work_cancel_match'


vim +73 kernel/task_work.c

e73f8959af0439 Oleg Nesterov 2012-05-11  60  
892f6668f3a708 Oleg Nesterov 2013-09-11  61  /**
c7aab1a7c52b82 Jens Axboe    2021-04-01  62   * task_work_cancel_match - cancel a pending work added by task_work_add()
892f6668f3a708 Oleg Nesterov 2013-09-11  63   * @task: the task which should execute the work
c7aab1a7c52b82 Jens Axboe    2021-04-01  64   * @match: match function to call
892f6668f3a708 Oleg Nesterov 2013-09-11  65   *
892f6668f3a708 Oleg Nesterov 2013-09-11  66   * RETURNS:
892f6668f3a708 Oleg Nesterov 2013-09-11  67   * The found work or NULL if not found.
892f6668f3a708 Oleg Nesterov 2013-09-11  68   */
67d1214551e800 Al Viro       2012-06-27  69  struct callback_head *
c7aab1a7c52b82 Jens Axboe    2021-04-01  70  task_work_cancel_match(struct task_struct *task,
c7aab1a7c52b82 Jens Axboe    2021-04-01  71  		       bool (*match)(struct callback_head *, void *data),
c7aab1a7c52b82 Jens Axboe    2021-04-01  72  		       void *data)
e73f8959af0439 Oleg Nesterov 2012-05-11 @73  {
ac3d0da8f3290b Oleg Nesterov 2012-08-26  74  	struct callback_head **pprev = &task->task_works;
205e550a0fb469 Oleg Nesterov 2013-09-11  75  	struct callback_head *work;
e73f8959af0439 Oleg Nesterov 2012-05-11  76  	unsigned long flags;
61e96496d3c949 Oleg Nesterov 2016-08-02  77  
61e96496d3c949 Oleg Nesterov 2016-08-02  78  	if (likely(!task->task_works))
61e96496d3c949 Oleg Nesterov 2016-08-02  79  		return NULL;
ac3d0da8f3290b Oleg Nesterov 2012-08-26  80  	/*
ac3d0da8f3290b Oleg Nesterov 2012-08-26  81  	 * If cmpxchg() fails we continue without updating pprev.
ac3d0da8f3290b Oleg Nesterov 2012-08-26  82  	 * Either we raced with task_work_add() which added the
ac3d0da8f3290b Oleg Nesterov 2012-08-26  83  	 * new entry before this work, we will find it again. Or
9da33de62431c7 Oleg Nesterov 2012-08-26  84  	 * we raced with task_work_run(), *pprev == NULL/exited.
ac3d0da8f3290b Oleg Nesterov 2012-08-26  85  	 */
e73f8959af0439 Oleg Nesterov 2012-05-11  86  	raw_spin_lock_irqsave(&task->pi_lock, flags);
506458efaf153c Will Deacon   2017-10-24  87  	while ((work = READ_ONCE(*pprev))) {
c7aab1a7c52b82 Jens Axboe    2021-04-01  88  		if (!match(work, data))
ac3d0da8f3290b Oleg Nesterov 2012-08-26  89  			pprev = &work->next;
ac3d0da8f3290b Oleg Nesterov 2012-08-26  90  		else if (cmpxchg(pprev, work, work->next) == work)
158e1645e07f3e Al Viro       2012-06-27  91  			break;
158e1645e07f3e Al Viro       2012-06-27  92  	}
e73f8959af0439 Oleg Nesterov 2012-05-11  93  	raw_spin_unlock_irqrestore(&task->pi_lock, flags);
ac3d0da8f3290b Oleg Nesterov 2012-08-26  94  
ac3d0da8f3290b Oleg Nesterov 2012-08-26  95  	return work;
e73f8959af0439 Oleg Nesterov 2012-05-11  96  }
e73f8959af0439 Oleg Nesterov 2012-05-11  97  

:::::: The code at line 73 was first introduced by commit
:::::: e73f8959af0439d114847eab5a8a5ce48f1217c4 task_work_add: generic process-context callbacks

:::::: TO: Oleg Nesterov <oleg@redhat.com>
:::::: CC: Al Viro <viro@zeniv.linux.org.uk>

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

Re: kernel/task_work.c:73: warning: Function parameter or member 'data' not described in 'task_work_cancel_match'

[Jens Axboe]

On 9/11/23 1:12 PM, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   0bb80ecc33a8fb5a682236443c1e740d5c917d1d
> commit: c7aab1a7c52b82d9afd7e03c398eb03dc2aa0507 task_work: add helper for more targeted task_work canceling
> date:   2 years, 5 months ago
> config: openrisc-allnoconfig (https://download.01.org/0day-ci/archive/20230912/202309120307.zis3yQGe-lkp@intel.com/config)
> compiler: or1k-linux-gcc (GCC) 12.3.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230912/202309120307.zis3yQGe-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/202309120307.zis3yQGe-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
>>> kernel/task_work.c:73: warning: Function parameter or member 'data' not described in 'task_work_cancel_match'

Wow, that got introduced with:

commit c7aab1a7c52b82d9afd7e03c398eb03dc2aa0507
Author: Jens Axboe <axboe@kernel.dk>
Date:   Thu Apr 1 19:53:29 2021 -0600

    task_work: add helper for more targeted task_work canceling

which is a while ago. In any case, this should fix it. I'll send out a
proper patch.


diff --git a/kernel/task_work.c b/kernel/task_work.c
index 065e1ef8fc8d..2a628b4a6124 100644
--- a/kernel/task_work.c
+++ b/kernel/task_work.c
@@ -78,6 +78,7 @@ int task_work_add(struct task_struct *task, struct callback_head *work,
  * task_work_cancel_match - cancel a pending work added by task_work_add()
  * @task: the task which should execute the work
  * @match: match function to call
+ * @data: data to pass into match function
  *
  * RETURNS:
  * The found work or NULL if not found.

-- 
Jens Axboe