linux-kernel - [PATCH] staging: iio: frequency: ad9832: Use div64_ul instead of do

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Message-ID: <Y1r+EHqpVz/HYrIm@ubunlion>
Date:   Fri, 28 Oct 2022 03:24:24 +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: frequency: ad9832: 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 identified using the
coccicheck tool.

Signed-off-by: Deepak R Varma <drv@...lo.com>
---
 drivers/staging/iio/frequency/ad9832.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/staging/iio/frequency/ad9832.c b/drivers/staging/iio/frequency/ad9832.c
index 6f9eebd6c7ee..a8409f6b1c4c 100644
--- a/drivers/staging/iio/frequency/ad9832.c
+++ b/drivers/staging/iio/frequency/ad9832.c
@@ -122,8 +122,7 @@ static unsigned long ad9832_calc_freqreg(unsigned long mclk, unsigned long fout)
 {
 	unsigned long long freqreg = (u64)fout *
 				     (u64)((u64)1L << AD9832_FREQ_BITS);
-	do_div(freqreg, mclk);
-	return freqreg;
+	return div64_ul(freqreg, mclk);
 }

 static int ad9832_write_frequency(struct ad9832_state *st,
--
2.34.1