linux-kernel - [PATCH] iio: common: ssp_sensors: Initialize calculated_time in ssp_common_process

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Message-Id: <20190307214546.9624-1-natechancellor@gmail.com>
Date:   Thu,  7 Mar 2019 14:45:46 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>
Subject: [PATCH] iio: common: ssp_sensors: Initialize calculated_time in ssp_common_process_data

When building with -Wsometimes-uninitialized, Clang warns:

drivers/iio/common/ssp_sensors/ssp_iio.c:95:6: warning: variable
'calculated_time' is used uninitialized whenever 'if' condition is false
[-Wsometimes-uninitialized]

While it isn't wrong, this will never be a problem because
iio_push_to_buffers_with_timestamp only uses calculated_time
on the same condition that it is assigned (when scan_timestamp
is not zero). While iio_push_to_buffers_with_timestamp is marked
as inline, Clang does inlining in the optimization stage, which
happens after the semantic analysis phase (plus inline is merely
a hint to the compiler).

Fix this by just zero initializing calculated_time.

Link: https://github.com/ClangBuiltLinux/linux/issues/394
Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
---
 drivers/iio/common/ssp_sensors/ssp_iio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/common/ssp_sensors/ssp_iio.c b/drivers/iio/common/ssp_sensors/ssp_iio.c
index 645f2e3975db..e38f704d88b7 100644
--- a/drivers/iio/common/ssp_sensors/ssp_iio.c
+++ b/drivers/iio/common/ssp_sensors/ssp_iio.c
@@ -81,7 +81,7 @@ int ssp_common_process_data(struct iio_dev *indio_dev, void *buf,
 			    unsigned int len, int64_t timestamp)
 {
 	__le32 time;
-	int64_t calculated_time;
+	int64_t calculated_time = 0;
 	struct ssp_sensor_data *spd = iio_priv(indio_dev);
 
 	if (indio_dev->scan_bytes == 0)
-- 
2.21.0