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lib/sbitmap: Fix invalid loop in __sbitmap_queue_get_batch()

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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: 9672b0d437 ("sbitmap: add __sbitmap_queue_get_batch()")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
wuchi 2022-06-05 22:58:35 +08:00 committed by Jens Axboe
parent e531485a0a
commit fbb564a557
1 changed files with 4 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

5
lib/sbitmap.c
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@ -528,7 +528,7 @@ unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags,
sbitmap_deferred_clear(map); sbitmap_deferred_clear(map);
if (map->word == (1UL << (map_depth - 1)) - 1) if (map->word == (1UL << (map_depth - 1)) - 1)
continue; goto next;
nr = find_first_zero_bit(&map->word, map_depth); nr = find_first_zero_bit(&map->word, map_depth);
if (nr + nr_tags <= 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; get_mask = ((1UL << map_tags) - 1) << nr;
do { do {
val = READ_ONCE(map->word); val = READ_ONCE(map->word);
if ((val & ~get_mask) != val)
goto next;
ret = atomic_long_cmpxchg(ptr, val, get_mask | val); ret = atomic_long_cmpxchg(ptr, val, get_mask | val);
} while (ret != val); } while (ret != val);
get_mask = (get_mask & ~ret) >> nr; 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; return get_mask;
} }
} }
next:
/* Jump to next index. */ /* Jump to next index. */
if (++index >= sb->map_nr) if (++index >= sb->map_nr)
index = 0; index = 0;