iio: prox: as3935: Fix buffer alignment in iio_push_to_buffers_with_timestamp()

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 uses of
iio_push_to_buffers_with_timestamp()

Fixes: 37b1ba2c68cf ("iio: proximity: as3935: fix buffer stack trashing")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Matt Ranostay <matt.ranostay@konsulko.com>
Acked-by: Matt Ranostay <matt.ranostay@konsulko.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210501170121.512209-15-jic23@kernel.org

diff --git a/drivers/iio/proximity/as3935.c b/drivers/iio/proximity/as3935.c
index dc20fe81232ce87ec53e5f23a2f9b1a6993b7e1f..3797a8f5427668b8e99f93a93853f1e92d669afc 100644 (file)
--- a/drivers/iio/proximity/as3935.c
+++ b/drivers/iio/proximity/as3935.c
@@ -59,7 +59,11 @@ struct as3935_state {
        unsigned long noise_tripped;
        u32 tune_cap;
        u32 nflwdth_reg;
-       u8 buffer[16]; /* 8-bit data + 56-bit padding + 64-bit timestamp */
+       /* Ensure timestamp is naturally aligned */
+       struct {
+               u8 chan;
+               s64 timestamp __aligned(8);
+       } scan;
        u8 buf[2] ____cacheline_aligned;
 };
 
@@ -225,8 +229,8 @@ static irqreturn_t as3935_trigger_handler(int irq, void *private)
        if (ret)
                goto err_read;
 
-       st->buffer[0] = val & AS3935_DATA_MASK;
-       iio_push_to_buffers_with_timestamp(indio_dev, &st->buffer,
+       st->scan.chan = val & AS3935_DATA_MASK;
+       iio_push_to_buffers_with_timestamp(indio_dev, &st->scan,
                                           iio_get_time_ns(indio_dev));
 err_read:
        iio_trigger_notify_done(indio_dev->trig);