linux-kernel - [PATCH] block: Use div64_ul instead of do

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Date:   Wed, 17 Nov 2021 01:03:58 +0000
From:   cgel.zte@...il.com
To:     tj@...nel.org
Cc:     axboe@...nel.dk, cgroups@...r.kernel.org,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        Changcheng Deng <deng.changcheng@....com.cn>,
        Zeal Robot <zealci@....com.cn>
Subject: [PATCH] block: Use div64_ul instead of do_div

From: Changcheng Deng <deng.changcheng@....com.cn>

do_div() does a 64-by-32 division. If the divisor is unsigned long, using
div64_ul can avoid truncation to 32-bit.

Reported-by: Zeal Robot <zealci@....com.cn>
Signed-off-by: Changcheng Deng <deng.changcheng@....com.cn>
---
 block/blk-throttle.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 39bb6e68a9a2..2db635d66617 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1903,7 +1903,7 @@ static void throtl_downgrade_check(struct throtl_grp *tg)
 
 	if (tg->bps[READ][LIMIT_LOW]) {
 		bps = tg->last_bytes_disp[READ] * HZ;
-		do_div(bps, elapsed_time);
+		div64_ul(bps, elapsed_time);
 		if (bps >= tg->bps[READ][LIMIT_LOW])
 			tg->last_low_overflow_time[READ] = now;
 	}
-- 
2.25.1