On Mon, 16 Oct 2023 14:04:11 +0300 Matti Vaittinen <mazziesaccount@xxxxxxxxx> wrote: > Sanity-check available_scan_masks array > > The available_scan_masks is an array of bitmasks representing the > channels which can be simultaneously(*) scanned by a driver from the > device. Following special characteristics apply: > > - When IIO is scanning through the array it will use the first mask > which can be used to scan all enabled channels. This means drivers > should order the array in the order of the preference. This does also > mean that a mask which is a subset of a mask located earler in array > will never be used because the earlier one will be picked by the core. > - Masks wider than size of long are supported only to some extent. The > code scanning through the array will interpret the first mask with > first long zeroed as end-of-array terminator. Changing this behaviour > would make mask-arrays for multi-long masks to be terminated by more > than one zero long. Failure to do so would result kernel to read > beyond the array generating a potentially hazardous bug. > > Add a sanity-check to IIO-device registration emitting a warning if > available_scan_mask array is misordered or if mask width is larger than > a long while available_scan_mask-array is populated. Currently there > should be no in-tree drivers with available_scan_mask populated and mask > wider than a long. > > Revision history: > v1 => v2: > - Add patch 2/2 documenting why iio_scan_mask_match() checks only > a long worth of bits while searching for the end of the > available_scan_mask-array. > - Styling of patch 1/2 as per comments from Jonathan > v1 and related discussion here: > https://lore.kernel.org/lkml/ZRvjuZaQWdZw1U1I@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > > Matti Vaittinen (2): > iio: sanity check available_scan_masks array > iio: buffer: document known issue > > drivers/iio/industrialio-buffer.c | 16 ++++++++ > drivers/iio/industrialio-core.c | 63 +++++++++++++++++++++++++++++++ > 2 files changed, 79 insertions(+) > Hi Matti, Just a quick note to say this looks fine to me, but I don't want to queue it up just yet given proximity to merge window etc. I'll aim to pick it up early in next cycle. Give me a poke if I still haven't by rc3 or so. Thanks, Jonathan
