2022-06-06 06:02:07

by wuchi

Subject: [PATCH] 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 <[email protected]>
---
lib/sbitmap.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index ae4fd4de9ebe..29eb0484215a 100644
--- 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;
--
2.20.1

2022-06-17 10:11:43

by wuchi

Subject: Re: [PATCH] lib/sbitmap: Fix invalid loop in __sbitmap_queue_get_batch()

Ping....

wuchi <[email protected]> 于2022年6月5日周日 22:58写道：
>
> 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 <[email protected]>
> ---
> lib/sbitmap.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/lib/sbitmap.c b/lib/sbitmap.c
> index ae4fd4de9ebe..29eb0484215a 100644
> --- 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;
> --
> 2.20.1
>

2022-06-25 00:04:40

by Martin Wilck

Subject: Re: [PATCH] lib/sbitmap: Fix invalid loop in __sbitmap_queue_get_batch()

On Sun, 2022-06-05 at 22:58 +0800, wuchi wrote:
> 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 <[email protected]>

Reviewed-by: Martin Wilck <[email protected]>

> ---
> ?lib/sbitmap.c | 5 ++++-
> ?1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/lib/sbitmap.c b/lib/sbitmap.c
> index ae4fd4de9ebe..29eb0484215a 100644
> --- 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;

2022-06-25 17:03:32

by Jens Axboe

Subject: Re: [PATCH] lib/sbitmap: Fix invalid loop in __sbitmap_queue_get_batch()

On 6/5/22 8:58 AM, wuchi wrote:
> 1. Getting next index before continue branch.
> 2. Checking free bits when setting the target bits. Otherwise,
> it may reuse the busying bits.

Applied with:

Fixes: 9672b0d43782 ("sbitmap: add __sbitmap_queue_get_batch()")

added as well.

--
Jens Axboe

2022-06-25 17:33:14

by Jens Axboe

Subject: Re: [PATCH] lib/sbitmap: Fix invalid loop in __sbitmap_queue_get_batch()

On Sun, 5 Jun 2022 22:58:35 +0800, wuchi wrote:
> 1. Getting next index before continue branch.
> 2. Checking free bits when setting the target bits. Otherwise,
> it may reuse the busying bits.
>
>

Applied, thanks!

[1/1] lib/sbitmap: Fix invalid loop in __sbitmap_queue_get_batch()
(no commit info)

Best regards,
--
Jens Axboe