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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 4.4 080/188] iio: accel: stk8ba50: Fix buffer alignment in iio_push_to_buffers_with_timestamp()
Date:   Mon, 19 Jul 2021 16:51:04 +0200
Message-Id: <20210719144931.670175142@linuxfoundation.org>
In-Reply-To: <20210719144913.076563739@linuxfoundation.org>
References: <20210719144913.076563739@linuxfoundation.org>
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From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

[ Upstream commit 334883894bc1e145a1e0f5de1b0d1b6a1133f0e6 ]

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: db6a19b8251f ("iio: accel: Add trigger support for STK8BA50")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210501170121.512209-8-jic23@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/iio/accel/stk8ba50.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/accel/stk8ba50.c b/drivers/iio/accel/stk8ba50.c
index 5709d9eb8f34..b6e2d15024c8 100644
--- a/drivers/iio/accel/stk8ba50.c
+++ b/drivers/iio/accel/stk8ba50.c
@@ -95,12 +95,11 @@ struct stk8ba50_data {
 	u8 sample_rate_idx;
 	struct iio_trigger *dready_trig;
 	bool dready_trigger_on;
-	/*
-	 * 3 x 16-bit channels (10-bit data, 6-bit padding) +
-	 * 1 x 16 padding +
-	 * 4 x 16 64-bit timestamp
-	 */
-	s16 buffer[8];
+	/* Ensure timestamp is naturally aligned */
+	struct {
+		s16 chans[3];
+		s64 timetamp __aligned(8);
+	} scan;
 };
 
 #define STK8BA50_ACCEL_CHANNEL(index, reg, axis) {			\
@@ -330,7 +329,7 @@ static irqreturn_t stk8ba50_trigger_handler(int irq, void *p)
 		ret = i2c_smbus_read_i2c_block_data(data->client,
 						    STK8BA50_REG_XOUT,
 						    STK8BA50_ALL_CHANNEL_SIZE,
-						    (u8 *)data->buffer);
+						    (u8 *)data->scan.chans);
 		if (ret < STK8BA50_ALL_CHANNEL_SIZE) {
 			dev_err(&data->client->dev, "register read failed\n");
 			goto err;
@@ -343,10 +342,10 @@ static irqreturn_t stk8ba50_trigger_handler(int irq, void *p)
 			if (ret < 0)
 				goto err;
 
-			data->buffer[i++] = ret;
+			data->scan.chans[i++] = ret;
 		}
 	}
-	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
+	iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
 					   pf->timestamp);
 err:
 	mutex_unlock(&data->lock);
-- 
2.30.2