linux-kernel - [PATCH] staging: iio: ad5933: Use div64_ul instead of do

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Date:   Fri, 28 Oct 2022 02:58:49 +0530
From:   Deepak R Varma <drv@...lo.com>
To:     outreachy@...ts.linux.dev, Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-iio@...r.kernel.org, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: [PATCH] staging: iio: ad5933: 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. Issue was identified using the
coccicheck tool.

Signed-off-by: Deepak R Varma <drv@...lo.com>
---
 drivers/staging/iio/impedance-analyzer/ad5933.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/iio/impedance-analyzer/ad5933.c b/drivers/staging/iio/impedance-analyzer/ad5933.c
index f177b20f0f2d..730bb31a20d8 100644
--- a/drivers/staging/iio/impedance-analyzer/ad5933.c
+++ b/drivers/staging/iio/impedance-analyzer/ad5933.c
@@ -196,7 +196,7 @@ static int ad5933_set_freq(struct ad5933_state *st,
 	} dat;

 	freqreg = (u64)freq * (u64)(1 << 27);
-	do_div(freqreg, st->mclk_hz / 4);
+	freqreg = div64_ul(freqreg, st->mclk_hz / 4);

 	switch (reg) {
 	case AD5933_REG_FREQ_START:
--
2.34.1