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authorYu Kuai <yukuai3@huawei.com>2022-08-29 10:22:38 +0800
committerJens Axboe <axboe@kernel.dk>2022-09-12 00:19:48 -0600
commit8d6bbaada2e0a65f9012ac4c2506460160e7237a (patch)
tree38f8337cf068641d2680da5e44e522b68b0f3434 /block/blk-throttle.c
parent320fb0f91e55ba248d4bad106b408e59099cfa89 (diff)
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blk-throttle: prevent overflow while calculating wait time
There is a problem found by code review in tg_with_in_bps_limit() that 'bps_limit * jiffy_elapsed_rnd' might overflow. Fix the problem by calling mul_u64_u64_div_u64() instead. Signed-off-by: Yu Kuai <yukuai3@huawei.com> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20220829022240.3348319-3-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-throttle.c')
-rw-r--r--block/blk-throttle.c8
1 files changed, 3 insertions, 5 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index a5e495b67827..353bbd0886ca 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -806,7 +806,7 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio,
u64 bps_limit, unsigned long *wait)
{
bool rw = bio_data_dir(bio);
- u64 bytes_allowed, extra_bytes, tmp;
+ u64 bytes_allowed, extra_bytes;
unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
unsigned int bio_size = throtl_bio_data_size(bio);
@@ -824,10 +824,8 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio,
jiffy_elapsed_rnd = tg->td->throtl_slice;
jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice);
-
- tmp = bps_limit * jiffy_elapsed_rnd;
- do_div(tmp, HZ);
- bytes_allowed = tmp;
+ bytes_allowed = mul_u64_u64_div_u64(bps_limit, (u64)jiffy_elapsed_rnd,
+ (u64)HZ);
if (tg->bytes_disp[rw] + bio_size <= bytes_allowed) {
if (wait)