linux-kernel - [PATCH] staging: pi433: use div64_u64() instead of do

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Message-Id: <1644396011-4450-1-git-send-email-wangqing@vivo.com>
Date:   Wed,  9 Feb 2022 00:40:10 -0800
From:   Qing Wang <wangqing@...o.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Cc:     Wang Qing <wangqing@...o.com>
Subject: [PATCH] staging: pi433: 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/staging/pi433/rf69.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/pi433/rf69.c b/drivers/staging/pi433/rf69.c
index 2ab3bf4..cef542d
--- a/drivers/staging/pi433/rf69.c
+++ b/drivers/staging/pi433/rf69.c
@@ -294,7 +294,7 @@ int rf69_set_deviation(struct spi_device *spi, u32 deviation)
 
 	// calculate register settings
 	f_reg = deviation * factor;
-	do_div(f_reg, f_step);
+	div64_u64(f_reg, f_step);
 
 	msb = (f_reg & 0xff00) >> 8;
 	lsb = (f_reg & 0xff);
-- 
2.7.4