From 554d21efb0d2e102a14f8c4b6bdfbcfbe54b3c65 Mon Sep 17 00:00:00 2001 From: Wen Yang Date: Mon, 20 Jan 2020 18:04:43 +0800 Subject: [PATCH] block, bfq: improve arithmetic division in bfq_delta() 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 Cc: Paolo Valente Cc: Jens Axboe Cc: linux-block@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Jens Axboe --- 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); } /**