From: Jonathan Cameron <jic23@kernel.org>
To: linux-iio@vger.kernel.org
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
Lars-Peter Clausen <lars@metafoo.de>,
Peter Meerwald <pmeerw@pmeerw.net>
Subject: [PATCH v4 6/8] iio:pressure:mpl3115: Force alignment of buffer
Date: Sun, 20 Sep 2020 12:27:40 +0100 [thread overview]
Message-ID: <20200920112742.170751-7-jic23@kernel.org> (raw)
In-Reply-To: <20200920112742.170751-1-jic23@kernel.org>
From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Whilst this is another case of the issue Lars reported with
an array of elements of smaller than 8 bytes being passed
to iio_push_to_buffers_with_timestamp(), the solution here is
a bit different from the other cases and relies on __aligned
working on the stack (true since 4.6?)
This one is unusual. We have to do an explicit memset() each time
as we are reading 3 bytes into a potential 4 byte channel which
may sometimes be a 2 byte channel depending on what is enabled.
As such, moving the buffer to the heap in the iio_priv structure
doesn't save us much. We can't use a nice explicit structure
on the stack either as the data channels have different storage
sizes and are all separately controlled.
Fixes: cc26ad455f57 ("iio: Add Freescale MPL3115A2 pressure / temperature sensor driver")
Reported-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Peter Meerwald <pmeerw@pmeerw.net>
---
v4: Added a 'special' comment as this one is unique.
drivers/iio/pressure/mpl3115.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/iio/pressure/mpl3115.c b/drivers/iio/pressure/mpl3115.c
index ccdb0b70e48c..1eb9e7b29e05 100644
--- a/drivers/iio/pressure/mpl3115.c
+++ b/drivers/iio/pressure/mpl3115.c
@@ -144,7 +144,14 @@ static irqreturn_t mpl3115_trigger_handler(int irq, void *p)
struct iio_poll_func *pf = p;
struct iio_dev *indio_dev = pf->indio_dev;
struct mpl3115_data *data = iio_priv(indio_dev);
- u8 buffer[16]; /* 32-bit channel + 16-bit channel + padding + ts */
+ /*
+ * 32-bit channel + 16-bit channel + padding + ts
+ * Note that it is possible for only one of the first 2
+ * channels to be enabled. If that happens, the first element
+ * of the buffer may be either 16 or 32-bits. As such we cannot
+ * use a simple structure definition to express this data layout.
+ */
+ u8 buffer[16] __aligned(8);
int ret, pos = 0;
mutex_lock(&data->lock);
--
2.28.0
next prev parent reply other threads:[~2020-09-20 11:28 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-20 11:27 [PATCH v4 0/8] IIO: Fused set 1 and 2 of timestamp alignment fixes Jonathan Cameron
2020-09-20 11:27 ` [PATCH v4 1/8] iio:light:rpr0521: Fix timestamp alignment and prevent data leak Jonathan Cameron
2020-09-20 11:27 ` [PATCH v4 2/8] iio:light:st_uvis25: " Jonathan Cameron
2020-09-20 11:27 ` [PATCH v4 3/8] iio:magnetometer:mag3110: Fix alignment and data leak issues Jonathan Cameron
2020-09-20 11:27 ` [PATCH v4 4/8] iio:imu:bmi160: Fix too large a buffer Jonathan Cameron
2020-09-20 11:27 ` [PATCH v4 5/8] iio:imu:bmi160: Fix alignment and data leak issues Jonathan Cameron
2020-09-20 11:27 ` Jonathan Cameron [this message]
2020-09-20 11:27 ` [PATCH v4 7/8] iio:adc:ti-ads124s08: Fix buffer being too long Jonathan Cameron
2020-09-20 11:27 ` [PATCH v4 8/8] iio:adc:ti-ads124s08: Fix alignment and data leak issues Jonathan Cameron
2020-11-29 13:22 ` [PATCH v4 0/8] IIO: Fused set 1 and 2 of timestamp alignment fixes Jonathan Cameron
2020-11-29 16:15 ` Alexandru Ardelean
2020-11-29 18:33 ` Jonathan Cameron
2020-11-29 20:26 ` Alexandru Ardelean
2020-11-30 13:13 ` Jonathan Cameron
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