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| author | Yu Kuai <yukuai3@huawei.com> | 2022-08-29 10:22:38 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2022-09-12 00:19:48 -0600 |
| commit | 8d6bbaada2e0a65f9012ac4c2506460160e7237a (patch) | |
| tree | 38f8337cf068641d2680da5e44e522b68b0f3434 /block/blk-throttle.c | |
| parent | 320fb0f91e55ba248d4bad106b408e59099cfa89 (diff) | |
| download | linux-8d6bbaada2e0a65f9012ac4c2506460160e7237a.tar.gz linux-8d6bbaada2e0a65f9012ac4c2506460160e7237a.tar.bz2 linux-8d6bbaada2e0a65f9012ac4c2506460160e7237a.zip | |
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.c | 8 |
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) |