linux-kernel - [PATCH -next] net: mvpp2: Use div64_ul instead of do

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Message-Id: <1637204701-8224-1-git-send-email-yang.lee@linux.alibaba.com>
Date:   Thu, 18 Nov 2021 11:05:01 +0800
From:   Yang Li <yang.lee@...ux.alibaba.com>
To:     davem@...emloft.net
Cc:     kuba@...nel.org, mw@...ihalf.com, linux@...linux.org.uk,
        ast@...nel.org, daniel@...earbox.net, hawk@...nel.org,
        john.fastabend@...il.com, andrii@...nel.org, kafai@...com,
        songliubraving@...com, yhs@...com, kpsingh@...nel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        bpf@...r.kernel.org, Yang Li <yang.lee@...ux.alibaba.com>
Subject: [PATCH -next] net: mvpp2: Use div64_ul instead of do_div

do_div() does a 64-by-32 division. Here the divisor is an
unsigned long which on some platforms is 64 bit wide. So use
div64_ul instead of do_div to avoid a possible truncation.

Eliminate the following coccicheck warning:
./drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c:2742:1-7: WARNING:
do_div() does a 64-by-32 division, please consider using div64_ul
instead.

Reported-by: Abaci Robot <abaci@...ux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@...ux.alibaba.com>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
index df6c793..41244a5 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
@@ -2739,7 +2739,7 @@ static u32 mvpp2_cycles_to_usec(u32 cycles, unsigned long clk_hz)
 {
 	u64 tmp = (u64)cycles * USEC_PER_SEC;
 
-	do_div(tmp, clk_hz);
+	tmp = div64_ul(tmp, clk_hz);
 
 	return tmp > U32_MAX ? U32_MAX : tmp;
 }
-- 
1.8.3.1