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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 097/245] iio: accel: stk8312: Fix buffer alignment in iio_push_to_buffers_with_timestamp()
Date:   Mon, 19 Jul 2021 16:50:39 +0200
Message-Id: <20210719144943.550000448@linuxfoundation.org>
In-Reply-To: <20210719144940.288257948@linuxfoundation.org>
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From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

[ Upstream commit f40a71ffec808e7e51848f63f0c0d3c32d65081b ]

To make code more readable, use a structure to express the channel
layout and ensure the timestamp is 8 byte aligned.

Found during an audit of all calls of this function.

Fixes: 95c12bba51c3 ("iio: accel: Add buffer mode for Sensortek STK8312")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210501170121.512209-7-jic23@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/iio/accel/stk8312.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/accel/stk8312.c b/drivers/iio/accel/stk8312.c
index e31023dc5f1b..24a7499049f1 100644
--- a/drivers/iio/accel/stk8312.c
+++ b/drivers/iio/accel/stk8312.c
@@ -106,7 +106,11 @@ struct stk8312_data {
 	u8 mode;
 	struct iio_trigger *dready_trig;
 	bool dready_trigger_on;
-	s8 buffer[16]; /* 3x8-bit channels + 5x8 padding + 64-bit timestamp */
+	/* Ensure timestamp is naturally aligned */
+	struct {
+		s8 chans[3];
+		s64 timestamp __aligned(8);
+	} scan;
 };
 
 static IIO_CONST_ATTR(in_accel_scale_available, STK8312_SCALE_AVAIL);
@@ -443,7 +447,7 @@ static irqreturn_t stk8312_trigger_handler(int irq, void *p)
 		ret = i2c_smbus_read_i2c_block_data(data->client,
 						    STK8312_REG_XOUT,
 						    STK8312_ALL_CHANNEL_SIZE,
-						    data->buffer);
+						    data->scan.chans);
 		if (ret < STK8312_ALL_CHANNEL_SIZE) {
 			dev_err(&data->client->dev, "register read failed\n");
 			mutex_unlock(&data->lock);
@@ -457,12 +461,12 @@ static irqreturn_t stk8312_trigger_handler(int irq, void *p)
 				mutex_unlock(&data->lock);
 				goto err;
 			}
-			data->buffer[i++] = ret;
+			data->scan.chans[i++] = ret;
 		}
 	}
 	mutex_unlock(&data->lock);
 
-	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
+	iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
 					   pf->timestamp);
 err:
 	iio_trigger_notify_done(indio_dev->trig);
-- 
2.30.2