From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: [PATCH AUTOSEL 5.15 15/47] blk-throttle: prevent overflow while calculating wait time Date: Wed, 12 Oct 2022 20:20:50 -0400 Message-ID: <20221013002124.1894077-15-sashal@kernel.org> References: <20221013002124.1894077-1-sashal@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1665620536; bh=tyY7mApUCKy3nxZR8IiT8fEapo3BTVDOMAVT+cOVgtA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=N0p6fCRMVoR/DoMxIjt2gjpCaaUzBn74/wiLh+bslI1tP9jXnmnz0jKR8EvU88QwZ kFOlUZHyitRTMExYHHdW/iVLDzpUwbQMcp43hTidOmBAB6xBdMPEY+CkXbY8YEx2di FE4MnLKUYIfZzDHTWy940waVyZRsm2Qs8FRqWR5nRR6Pmurl/qcb586gVC0ksNY5HA gvA+97D7I5jTw6ePtxBuIX+FLrPQG4B/VnXZpqoBIliQWBWx9nq8IvGnQsmFV5H6EZ ExmbLzKBoO9FrK58+X4Q2S9YZKp3N3IqWBkUGQS2c6J0iy/FVJ8FXxBJ2PKtqOtM/L S7QpCkME2hJiQ== In-Reply-To: <20221013002124.1894077-1-sashal@kernel.org> List-ID: Content-Type: text/plain; charset="us-ascii" To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Yu Kuai , Tejun Heo , Jens Axboe , Sasha Levin , cgroups@vger.kernel.org, linux-block@vger.kernel.org From: Yu Kuai [ Upstream commit 8d6bbaada2e0a65f9012ac4c2506460160e7237a ] 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 Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20220829022240.3348319-3-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-throttle.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 7c4e7993ba97..68cf8dbb4c67 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -950,7 +950,7 @@ 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); @@ -967,10 +967,8 @@ 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) -- 2.35.1