[android-common:android15-6.6-2025-10 1/1] lib/sbitmap.c:104: warning: Function parameter or member 'sb' not described in 'sbitmap_spinlock'

[android-common:android15-6.6-2025-10 1/1] lib/sbitmap.c:104: warning: Function parameter or member 'sb' not described in 'sbitmap_spinlock'

[kernel test robot]

Hi Bart,

FYI, the error/warning still remains.

tree:   https://android.googlesource.com/kernel/common android15-6.6-2025-10
head:   bb7218bc09c920f6ff72bf0b939cf88fa52736ff
commit: 05baf38affa65735b6698f089e82af7c0e17b349 [1/1] ANDROID: sbitmap: Fix sbitmap_spinlock()
config: arm64-allnoconfig (https://download.01.org/0day-ci/archive/20260716/202607161823.2stQ8bZY-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 16.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260716/202607161823.2stQ8bZY-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/202607161823.2stQ8bZY-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> lib/sbitmap.c:104: warning: Function parameter or member 'sb' not described in 'sbitmap_spinlock'
>> lib/sbitmap.c:104: warning: Excess function parameter 'map' description in 'sbitmap_spinlock'
>> lib/sbitmap.c:104: warning: Excess function parameter 'map_nr' description in 'sbitmap_spinlock'


vim +104 lib/sbitmap.c

bf2c4282a10a92 Ming Lei        2021-01-22   59  
783d6780cd6684 Yang Yang       2024-07-16   60  /**
783d6780cd6684 Yang Yang       2024-07-16   61   * sbitmap_spinlock() - Get the spinlock corresponding to sbitmap_work.
783d6780cd6684 Yang Yang       2024-07-16   62   * @map: The memory address of the index sbitmap_work area.
783d6780cd6684 Yang Yang       2024-07-16   63   * @map_nr: Number of words (cachelines) being used for the bitmap.
783d6780cd6684 Yang Yang       2024-07-16   64   * @index: The index of the spinlock.
783d6780cd6684 Yang Yang       2024-07-16   65   *
783d6780cd6684 Yang Yang       2024-07-16   66   * this lock: serializes simultaneous updates of ->word and ->cleared.
783d6780cd6684 Yang Yang       2024-07-16   67   * sbitmap_spinlock is for checking on ->cleared and updating on both
783d6780cd6684 Yang Yang       2024-07-16   68   * ->cleared and ->word need to be done atomically.
783d6780cd6684 Yang Yang       2024-07-16   69   *  Prevent the following situations from causing block:
783d6780cd6684 Yang Yang       2024-07-16   70   * Configuration for sbq:
783d6780cd6684 Yang Yang       2024-07-16   71   * depth=64, wake_batch=6, shift=6, map_nr=1
783d6780cd6684 Yang Yang       2024-07-16   72   *
783d6780cd6684 Yang Yang       2024-07-16   73   * 1. There are 64 requests in progress:
783d6780cd6684 Yang Yang       2024-07-16   74   * map->word = 0xFFFFFFFFFFFFFFFF
783d6780cd6684 Yang Yang       2024-07-16   75   * 2. After all the 64 requests complete, and no more requests come:
783d6780cd6684 Yang Yang       2024-07-16   76   * map->word = 0xFFFFFFFFFFFFFFFF, map->cleared = 0xFFFFFFFFFFFFFFFF
783d6780cd6684 Yang Yang       2024-07-16   77   * 3. Now two tasks try to allocate requests:
783d6780cd6684 Yang Yang       2024-07-16   78   * T1:                                       T2:
783d6780cd6684 Yang Yang       2024-07-16   79   * __blk_mq_get_tag                          .
783d6780cd6684 Yang Yang       2024-07-16   80   * __sbitmap_queue_get                       .
783d6780cd6684 Yang Yang       2024-07-16   81   * sbitmap_get                               .
783d6780cd6684 Yang Yang       2024-07-16   82   * sbitmap_find_bit                          .
783d6780cd6684 Yang Yang       2024-07-16   83   * sbitmap_find_bit_in_word                  .
783d6780cd6684 Yang Yang       2024-07-16   84   * sbitmap_get_word  -> nr=-1              __blk_mq_get_tag
783d6780cd6684 Yang Yang       2024-07-16   85   * sbitmap_deferred_clear                    __sbitmap_queue_get
783d6780cd6684 Yang Yang       2024-07-16   86   * //map->cleared=0xFFFFFFFFFFFFFFFF         sbitmap_find_bit
783d6780cd6684 Yang Yang       2024-07-16   87   *   if (!READ_ONCE(map->cleared))           sbitmap_find_bit_in_word
783d6780cd6684 Yang Yang       2024-07-16   88   *     return false;                         __sbitmap_get_word -> nr=-1
783d6780cd6684 Yang Yang       2024-07-16   89   * mask = xchg(&map->cleared, 0)             sbitmap_deferred_clear
783d6780cd6684 Yang Yang       2024-07-16   90   * atomic_long_andnot()                      // map->cleared=0
783d6780cd6684 Yang Yang       2024-07-16   91   *                                             if (!(map->cleared))
783d6780cd6684 Yang Yang       2024-07-16   92   *                                               return false;
783d6780cd6684 Yang Yang       2024-07-16   93   *
783d6780cd6684 Yang Yang       2024-07-16   94   *                                    // map->cleared is cleared by T1
783d6780cd6684 Yang Yang       2024-07-16   95   *                                    // T2 fail to acquire the tag
783d6780cd6684 Yang Yang       2024-07-16   96   *
783d6780cd6684 Yang Yang       2024-07-16   97   * 4. T2 is the sole tag waiter. When T1 puts the tag, T2 cannot be woken
783d6780cd6684 Yang Yang       2024-07-16   98   * up due to the wake_batch being set at 6. If no more requests come, T1
783d6780cd6684 Yang Yang       2024-07-16   99   * will wait here indefinitely.
783d6780cd6684 Yang Yang       2024-07-16  100   *
783d6780cd6684 Yang Yang       2024-07-16  101   * Return: Returns the spinlock corresponding to index.
783d6780cd6684 Yang Yang       2024-07-16  102   */
05baf38affa657 Bart Van Assche 2025-04-03  103  static spinlock_t *sbitmap_spinlock(struct sbitmap *sb, unsigned int index)
783d6780cd6684 Yang Yang       2024-07-16 @104  {
05baf38affa657 Bart Van Assche 2025-04-03  105  	const unsigned int max_map_nr = *(unsigned int *)&sb->map[-1];
05baf38affa657 Bart Van Assche 2025-04-03  106  	spinlock_t *const base_lock = (spinlock_t *)
05baf38affa657 Bart Van Assche 2025-04-03  107  		round_up((uintptr_t)&sb->map[max_map_nr],
05baf38affa657 Bart Van Assche 2025-04-03  108  			 __alignof__(spinlock_t));
05baf38affa657 Bart Van Assche 2025-04-03  109  
05baf38affa657 Bart Van Assche 2025-04-03  110  	WARN_ON_ONCE(index < 0 || index >= sb->map_nr);
783d6780cd6684 Yang Yang       2024-07-16  111  
783d6780cd6684 Yang Yang       2024-07-16  112  	return &base_lock[index];
783d6780cd6684 Yang Yang       2024-07-16  113  }
783d6780cd6684 Yang Yang       2024-07-16  114  

:::::: The code at line 104 was first introduced by commit
:::::: 783d6780cd66848c96945c8143a808a2b98c9836 ANDROID: Fixed the KMI corruption issue caused by the patch of 72d04bdcf3f7.

:::::: TO: Yang Yang <yang.yang@vivo.com>
:::::: CC: Todd Kjos <tkjos@google.com>

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