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Subject[PATCH] block, bfq: improve arithmetic division in bfq_delta()
Date
do_div() does a 64-by-32 division. Use div64_ul() instead of it
if the divisor is unsigned long, to avoid truncation to 32-bit.
And as a nice side effect also cleans up the function a bit.

Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
Cc: Paolo Valente <paolo.valente@linaro.org>
Cc: Jens Axboe <axboe@fb.com>
Cc: linux-block@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
block/bfq-wf2q.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
index 05f0bf4a1144..ffe9ce9faa89 100644
--- a/block/bfq-wf2q.c
+++ b/block/bfq-wf2q.c
@@ -277,10 +277,7 @@ struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity)
*/
static u64 bfq_delta(unsigned long service, unsigned long weight)
{
- u64 d = (u64)service << WFQ_SERVICE_SHIFT;
-
- do_div(d, weight);
- return d;
+ return div64_ul((u64)service << WFQ_SERVICE_SHIFT, weight);
}

/**
--
2.23.0
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