The documentation explains the need to create internal syscalls' helpers,
and that they should be called `kern_xyzzy()`. However, the comment at
include/linux/syscalls.h says that they should be named as
`ksys_xyzzy()`, and so are all the helpers declared bellow it. Change the
documentation to reflect this.
Fixes: 819671ff84 ("syscalls: define and explain goal to not call syscalls in the kernel")
Signed-off-by: André Almeida <andrealmeid@collabora.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Link: https://lore.kernel.org/r/20210130014547.123006-1-andrealmeid@collabora.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Document that backtraces in commit messages should be trimmed down to
the useful information only.
This has been carved out from a tip subsystem handbook patchset by
Thomas Gleixner:
https://lkml.kernel.org/r/20181107171010.421878737@linutronix.de
and incorporates follow-on comments.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The kernel build system as a whole is dropping support for Python 2, so we
should do the same. The effects are rather small, especially considering
that much of the deleted code was not doing anything under any version of
Python anyway.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
As promised, drop support for some ancient sphinx releases, along with a
lot of the cruft that was required to make that support work.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
ABS_PRESSURE and ABS_MT_PRESSURE on touch devices usually represent
contact size (as a finger flattens with higher pressure the contact size
increases) and userspace translates the kernel pressure value back into
contact size. For example, libinput has pressure thresholds when a touch is
considered a palm (palm == large contact area -> high pressure). The values
themselves are on an arbitrary scale and device-specific.
On pressurepads however, the pressure axis may represent the real physical
pressure. Pressurepads are touchpads without a hinge but an actual pressure
sensor underneath the device instead, for example the Lenovo Yoga 9i.
A high-enough pressure is converted to a button click by the firmware.
Microsoft does not require a pressure axis to be present, see [1], so as seen
from userspace most pressurepads are identical to clickpads - one button and
INPUT_PROP_BUTTONPAD set.
However, pressurepads that export the pressure axis break userspace because
that axis no longer represents contact size, resulting in inconsistent touch
tracking, e.g. [2]. Userspace needs to know when a pressure axis represents
real pressure and the best way to do so is to define what the resolution
field means. Userspace can then treat data with a pressure resolution as
true pressure.
This patch documents that the pressure resolution is in units/gram. This
allows for fine-grained detail and tops out at roughly ~2000t, enough for the
devices we're dealing with. Grams is not a scientific pressure unit but the
alternative is:
- Pascal: defined as force per area and area is unreliable on many devices and
seems like the wrong option here anyway, especially for devices with a
single pressure sensor only.
- Newton: defined as mass * distance/acceleration and for the purposes of a
pressure axis, the distance is tricky to interpret and we get the data to
calculate acceleration from event timestamps anyway.
For the purposes of touch devices and digitizers, grams seems the best choice
and the easiest to interpret.
Bonus side effect: we can use the existing hwdb infrastructure in userspace to
fix devices that advertise false pressure.
[1] https://docs.microsoft.com/en-us/windows-hardware/design/component-guidelines/windows-precision-touchpad-required-hid-top-level-collections#windows-precision-touchpad-input-reports
[2] https://gitlab.freedesktop.org/libinput/libinput/-/issues/562
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Link: https://lore.kernel.org/r/20210112230310.GA149342@jelly
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The kernel-doc markups on this file are weird: they don't
follow what's specified at:
Documentation/doc-guide/kernel-doc.rst
In particular, markups should use this format:
identifier - description
and not this:
identifier(args)
The way the definitions are inside this file cause the
parser to completely miss the identifier name of each
function.
This prevents improving the script to do some needed validation
tests.
Address this part. Yet, furter changes are needed in order
for it to fully follow the specs.
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/8383758160fdb4fcbb2ac56beeb874ca6dffc6b9.1610610937.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Commit adab66b71a ("Revert: "ring-buffer: Remove HAVE_64BIT_ALIGNED_ACCESS"")
added the config HAVE_64BIT_ALIGNED_ACCESS back into arch/Kconfig with this
revert. In the meantime, commit c9b54d6f36 ("docs: move other kAPI
documents to core-api") changed ./Documentation/unaligned-memory-access.txt
to ./Documentation/core-api/unaligned-memory-access.rst.
Fortunately, ./scripts/documentation-file-ref-check detects this and warns
about this broken reference.
Update the file reference in arch/Kconfig.
Fixes: adab66b71a ("Revert: "ring-buffer: Remove HAVE_64BIT_ALIGNED_ACCESS"")
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/r/20210119095326.13896-1-lukas.bulwahn@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
These two places are rendered like a table in the source (rst) code,
but they are seen as plain text by formatters, and thus are joined
together into a single line, e.g.:
> “root” - a partition root “member” - a non-root member of a partition
This is definitely not what was intended.
To fix, use table formatting, like in other places.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20210120001824.385168-9-kolyshkin@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Kernel-doc currently expects that the kernel-doc markup to come
just before the function/enum/struct/union/typedef prototype.
Yet, if it find things like:
/**
* refcount_add - add a value to a refcount
* @i: the value to add to the refcount
* @r: the refcount
*/
static inline void __refcount_add(int i, refcount_t *r, int *oldp);
static inline void refcount_add(int i, refcount_t *r);
Kernel-doc will do the wrong thing:
foobar.h:6: warning: Function parameter or member 'oldp' not described in '__refcount_add'
.. c:function:: void __refcount_add (int i, refcount_t *r, int *oldp)
add a value to a refcount
**Parameters**
``int i``
the value to add to the refcount
``refcount_t *r``
the refcount
``int *oldp``
*undescribed*
Basically, it will document "__refcount_add" with the kernel-doc
markup for refcount_add.
If both functions have the same arguments, this won't even
produce any warning!
Add a logic to check if the kernel-doc identifier matches the actual
name of the C function or data structure that will be documented.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/081546f141a496d6cabb99a4adc140444c705e93.1610610937.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
