From: Wen Yang <wenyang@linux.alibaba.com>
Date: Mon, 20 Jan 2020 18:04:43 +0800
Subject: [PATCH] block, bfq: improve arithmetic division in bfq_delta()
References: bsc#1175995,jsc#SLE-15608
Git-commit: 554d21efb0d2e102a14f8c4b6bdfbcfbe54b3c65
Patch-mainline: v5.6-rc1
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
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
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 44079147e396..84be5482bcf3 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);
}
/**
--
2.16.4