lib/sbitmap: Fix invalid loop in __sbitmap_queue_get_batch()

1. Getting next index before continue branch.
2. Checking free bits when setting the target bits. Otherwise,
it may reuse the busying bits.

Signed-off-by: wuchi <wuchi.zero@gmail.com>
Reviewed-by: Martin Wilck <mwilck@suse.com>
Link: https://lore.kernel.org/r/20220605145835.26916-1-wuchi.zero@gmail.com
Fixes: 1deeb5d73a89 ("sbitmap: add __sbitmap_queue_get_batch()")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index ae4fd4de9ebe781603e27c4c0a3a67a5ba0477df..29eb0484215afd190d78434850cea9b47b21b848 100644 (file)
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -528,7 +528,7 @@ unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags,
 
                sbitmap_deferred_clear(map);
                if (map->word == (1UL << (map_depth - 1)) - 1)
-                       continue;
+                       goto next;
 
                nr = find_first_zero_bit(&map->word, map_depth);
                if (nr + nr_tags <= map_depth) {
@@ -539,6 +539,8 @@ unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags,
                        get_mask = ((1UL << map_tags) - 1) << nr;
                        do {
                                val = READ_ONCE(map->word);
+                               if ((val & ~get_mask) != val)
+                                       goto next;
                                ret = atomic_long_cmpxchg(ptr, val, get_mask | val);
                        } while (ret != val);
                        get_mask = (get_mask & ~ret) >> nr;
@@ -549,6 +551,7 @@ unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags,
                                return get_mask;
                        }
                }
+next:
                /* Jump to next index. */
                if (++index >= sb->map_nr)
                        index = 0;