On 17/07/14 16:59, Lars-Peter Clausen wrote:
ALIGN() only works correctly if the alignment is a power of two. Some drivers
use 3 bytes for the storage size of the word in which case ALIGN() will cause
incorrect results. Use the more generic roundup() instead.
Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
Gah. Which driver is using a non power of two storage size? I thought I'd caught
all of those at review. As you've noted it's a very bad idea.
From a quick dubious grep I have:
dac/ad5791.c (not effected as such given we aren't using this stuff for output)
pressure/st_pressure_core.c
I'd be tempted to fix those up rather than change this and introduce the
fun you've pointed out below.
What do you think?
---
This at least makes the rules for alignment predictable and consistent. But
mixing 3 bytes words with other word sizes will still result in strange layouts.
E.g. 4-byte word, 3-byte word will result in 4-byte word, 2-byte alignment gap,
3-byte word.
---
drivers/iio/industrialio-buffer.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 0472ee2..6da5272 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -486,7 +486,7 @@ static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
ch->scan_type.repeat;
else
length = ch->scan_type.storagebits / 8;
- bytes = ALIGN(bytes, length);
+ bytes = roundup(bytes, length);
bytes += length;
}
if (timestamp) {
@@ -497,7 +497,7 @@ static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
ch->scan_type.repeat;
else
length = ch->scan_type.storagebits / 8;
- bytes = ALIGN(bytes, length);
+ bytes = roundup(bytes, length);
bytes += length;
}
return bytes;
--
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