linux-kernel - [PATCH] net: ethernet: cavium: use div64_u64() instead of do

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Date:   Wed,  9 Feb 2022 00:39:19 -0800
From:   Qing Wang <wangqing@...o.com>
To:     Derek Chickles <dchickles@...vell.com>,
        Satanand Burla <sburla@...vell.com>,
        Felix Manlunas <fmanlunas@...vell.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Wang Qing <wangqing@...o.com>
Subject: [PATCH] net: ethernet: cavium: use div64_u64() instead of do_div()

From: Wang Qing <wangqing@...o.com>

do_div() does a 64-by-32 division.
When the divisor is u64, do_div() truncates it to 32 bits, this means it
can test non-zero and be truncated to zero for division.

fix do_div.cocci warning:
do_div() does a 64-by-32 division, please consider using div64_u64 instead.

Signed-off-by: Wang Qing <wangqing@...o.com>
---
 drivers/net/ethernet/cavium/liquidio/lio_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/cavium/liquidio/lio_main.c b/drivers/net/ethernet/cavium/liquidio/lio_main.c
index ba28aa4..8e07192
--- a/drivers/net/ethernet/cavium/liquidio/lio_main.c
+++ b/drivers/net/ethernet/cavium/liquidio/lio_main.c
@@ -1539,7 +1539,7 @@ static int liquidio_ptp_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
 	 * compute the delta in terms of coprocessor clocks.
 	 */
 	delta = (u64)ppb << 32;
-	do_div(delta, oct->coproc_clock_rate);
+	div64_u64(delta, oct->coproc_clock_rate);
 
 	spin_lock_irqsave(&lio->ptp_lock, flags);
 	comp = lio_pci_readq(oct, CN6XXX_MIO_PTP_CLOCK_COMP);
@@ -1672,7 +1672,7 @@ static void liquidio_ptp_init(struct octeon_device *oct)
 	u64 clock_comp, cfg;
 
 	clock_comp = (u64)NSEC_PER_SEC << 32;
-	do_div(clock_comp, oct->coproc_clock_rate);
+	div64_u64(clock_comp, oct->coproc_clock_rate);
 	lio_pci_writeq(oct, clock_comp, CN6XXX_MIO_PTP_CLOCK_COMP);
 
 	/* Enable */
-- 
2.7.4