linux-kernel - [PATCH v2] iioc: dac: ltc2664: Fix span variable usage in ltc2664_channel

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Message-ID: <20241005170722.19542-1-pvmohammedanees2003@gmail.com>
Date: Sat,  5 Oct 2024 22:37:22 +0530
From: Mohammed Anees <pvmohammedanees2003@...il.com>
To: linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Michael Hennerich <michael.hennerich@...log.com>,
	Kim Seer Paller <kimseer.paller@...log.com>,
	Jonathan Cameron <jic23@...nel.org>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Mohammed Anees <pvmohammedanees2003@...il.com>
Subject: [PATCH v2] iioc: dac: ltc2664: Fix span variable usage in ltc2664_channel_config function

In the current implementation of the ltc2664_channel_config function,
a variable named span is declared and initialized to 0, intended to
capture the return value of the ltc2664_set_span function. However,
the output of ltc2664_set_span is directly assigned to chan->span,
leaving span unchanged. As a result, when the function later checks
if (span < 0), this condition will never trigger an error since
span remains 0, this flaw leads to ineffective error handling. The
current patch resolves this issue by using the ret variable for 
getting the return value, later assigning if successful and also 
effectively removing span variable.

Signed-off-by: Mohammed Anees <pvmohammedanees2003@...il.com>
Fixes: 4cc2fc445d2e4e63ed6bd5d310752d88d365f8e4
---
v2:
- Using the ret variable to store the result from ltc2664_set_span
---
 drivers/iio/dac/ltc2664.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/iio/dac/ltc2664.c b/drivers/iio/dac/ltc2664.c
index 5be5345ac5c8..7dafcba7ece7 100644
--- a/drivers/iio/dac/ltc2664.c
+++ b/drivers/iio/dac/ltc2664.c
@@ -516,7 +516,7 @@ static int ltc2664_channel_config(struct ltc2664_state *st)
 	const struct ltc2664_chip_info *chip_info = st->chip_info;
 	struct device *dev = &st->spi->dev;
 	u32 reg, tmp[2], mspan;
-	int ret, span = 0;
+	int ret;
 
 	mspan = LTC2664_MSPAN_SOFTSPAN;
 	ret = device_property_read_u32(dev, "adi,manual-span-operation-config",
@@ -579,20 +579,24 @@ static int ltc2664_channel_config(struct ltc2664_state *st)
 		ret = fwnode_property_read_u32_array(child, "output-range-microvolt",
 						     tmp, ARRAY_SIZE(tmp));
 		if (!ret && mspan == LTC2664_MSPAN_SOFTSPAN) {
-			chan->span = ltc2664_set_span(st, tmp[0] / 1000,
+			ret = ltc2664_set_span(st, tmp[0] / 1000,
 						      tmp[1] / 1000, reg);
-			if (span < 0)
-				return dev_err_probe(dev, span,
+			if (ret < 0)
+				return dev_err_probe(dev, ret,
 						     "Failed to set span\n");
+			else
+				chan->span = ret;
 		}
 
 		ret = fwnode_property_read_u32_array(child, "output-range-microamp",
 						     tmp, ARRAY_SIZE(tmp));
 		if (!ret) {
-			chan->span = ltc2664_set_span(st, 0, tmp[1] / 1000, reg);
-			if (span < 0)
-				return dev_err_probe(dev, span,
+			ret = ltc2664_set_span(st, 0, tmp[1] / 1000, reg);
+			if (ret < 0)
+				return dev_err_probe(dev, ret,
 						     "Failed to set span\n");
+			else
+				chan->span = ret;
 		}
 	}
 
-- 
2.46.0