| Message ID | cover.1697452986.git.mazziesaccount@gmail.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Sanity-check available_scan_masks array | expand |
On Mon, 16 Oct 2023 14:04:11 +0300 Matti Vaittinen <mazziesaccount@gmail.com> 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@dc78bmyyyyyyyyyyyyydt-3.rev.dnainternet.fi/ > > 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
On 10/21/23 18:55, Jonathan Cameron wrote: > On Mon, 16 Oct 2023 14:04:11 +0300 > Matti Vaittinen <mazziesaccount@gmail.com> 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@dc78bmyyyyyyyyyyyyydt-3.rev.dnainternet.fi/ >> >> 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. Makes perfect sense to me. > I'll aim to pick it up early > in next cycle. Give me a poke if I still haven't by rc3 or so. Ouch... My memory gets worse year by year - well, I'll try to remember :) Yours, -- Matti
On Sat, 21 Oct 2023 19:03:15 +0300 Matti Vaittinen <mazziesaccount@gmail.com> wrote: > On 10/21/23 18:55, Jonathan Cameron wrote: > > On Mon, 16 Oct 2023 14:04:11 +0300 > > Matti Vaittinen <mazziesaccount@gmail.com> 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@dc78bmyyyyyyyyyyyyydt-3.rev.dnainternet.fi/ > >> > >> 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. > > Makes perfect sense to me. > > > I'll aim to pick it up early > > in next cycle. Give me a poke if I still haven't by rc3 or so. > > Ouch... My memory gets worse year by year - well, I'll try to remember :) I've started queuing stuff up for rebasing post merge window, so I've added this as well. For now will only be exposed as the testing branch that 0-day pokes at. Thanks, Jonathan > > Yours, > -- Matti >
On 10/28/23 19:32, Jonathan Cameron wrote: > On Sat, 21 Oct 2023 19:03:15 +0300 > Matti Vaittinen <mazziesaccount@gmail.com> wrote: > >> On 10/21/23 18:55, Jonathan Cameron wrote: >>> On Mon, 16 Oct 2023 14:04:11 +0300 >>> Matti Vaittinen <mazziesaccount@gmail.com> 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@dc78bmyyyyyyyyyyyyydt-3.rev.dnainternet.fi/ >>>> >>>> Matti Vaittinen (2): >>>> iio: sanity check available_scan_masks array >>>> iio: buffer: document known issue ... > > I've started queuing stuff up for rebasing post merge window, so I've > added this as well. For now will only be exposed as the testing branch > that 0-day pokes at. Thanks Jonathan!