diff options
| author | Matti Vaittinen <mazziesaccount@gmail.com> | 2023-10-16 14:04:55 +0300 |
|---|---|---|
| committer | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2023-11-16 19:10:28 +0000 |
| commit | 6543f376ec8aa90a6c1ed44b765f4f0d6c3eb1db (patch) | |
| tree | 275d146cbe4ec19255389bd42ee599ba061af44f | |
| parent | 2718f15403fbbff4c4116824e02537e39342986a (diff) | |
iio: buffer: document known issue
Add documentation explaining why the code which scans all available scan
masks is checking only a single long worth of bits even though the code
was intended to be supporting masks wider than single long.
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://lore.kernel.org/r/ef61c2c1e9a1c5e9f713f656871fdcb1652afdc2.1697452986.git.mazziesaccount@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
| -rw-r--r-- | drivers/iio/industrialio-buffer.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c index 176d31d9f9d8..09c41e9ccf87 100644 --- a/drivers/iio/industrialio-buffer.c +++ b/drivers/iio/industrialio-buffer.c @@ -413,6 +413,22 @@ static const unsigned long *iio_scan_mask_match(const unsigned long *av_masks, { if (bitmap_empty(mask, masklength)) return NULL; + /* + * The condition here do not handle multi-long masks correctly. + * It only checks the first long to be zero, and will use such mask + * as a terminator even if there was bits set after the first long. + * + * Correct check would require using: + * while (!bitmap_empty(av_masks, masklength)) + * instead. This is potentially hazardous because the + * avaliable_scan_masks is a zero terminated array of longs - and + * using the proper bitmap_empty() check for multi-long wide masks + * would require the array to be terminated with multiple zero longs - + * which is not such an usual pattern. + * + * As writing of this no multi-long wide masks were found in-tree, so + * the simple while (*av_masks) check is working. + */ while (*av_masks) { if (strict) { if (bitmap_equal(mask, av_masks, masklength)) |