A k_futex is a lightweight mutual exclusion primitive designed
to minimize kernel involvement. Uncontended operation relies
only on atomic access to shared memory. k_futex structure lives
in application memory. And when using futexes, the majority of
the synchronization operations are performed in user mode. A
user-mode thread employs the futex wait system call only when
it is likely that the program has to block for a longer time
until the condition becomes true. When the condition comes true,
futex wake operation will be used to wake up one or more threads
waiting on that futex.
This patch implements two futex operations: k_futex_wait and
k_futex_wake. For k_futex_wait, the comparison with the expected
value, and starting to sleep are performed atomically to prevent
lost wake-ups. If different context changed futex's value after
the calling use-mode thread decided to block himself based on
the old value, the comparison will help observing the value
change and will not start to sleep. And for k_futex_wake, it
will wake at most num_waiters of the waiters that are sleeping
on that futex. But no guarantees are made on which threads are
woken, that means scheduling priority is not taken into
consideration.
Fixes: #14493.
Signed-off-by: Wentong Wu <wentong.wu@intel.com>
For systems without userspace enabled, these work the same
as a k_mutex.
For systems with userspace, the sys_mutex may exist in user
memory. It is still tracked as a kernel object, but has an
underlying k_mutex that is looked up in the kernel object
table.
Future enhancements will optimize sys_mutex to not require
syscalls for uncontended sys_mutexes, using atomic ops
instead.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
Some forthcoming kernel object types like futexes need to
be tracked, but do not contain data that is private to
the kernel.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
self.num_members doesn't exist. This commit just removes the reference,
because I didn't want to guess a proper fix.
Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>
Using a member variable in the dict comprehension was probably a typo
(can't see 'sym' referenced elsewhere). Use a local variable instead.
Made pylint spit out these warnings (which might be spurious though):
scripts/elf_helper.py:535:24: E0203: Access to member 'sym' before
its definition line 536 (access-member-before-definition)
scripts/elf_helper.py:535:39: E0203: Access to member 'sym' before
its definition line 536 (access-member-before-definition)
Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>
Discovered with pylint3.
Use the placeholder name '_' for unproblematic unused variables. It's
what I'm used to, and pylint knows not to flag it.
Python tip:
for i in range(n):
some_list.append(0)
can be replaced with
some_list += n*[0]
Similarly, 3*'\t' gives '\t\t\t'.
(Relevant here because pylint flagged the loop index as unused.)
To do integer division in Python 3, use // instead of /.
Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>
debug_die() is not implemented in this class, and indeed we
don't even have a reference to the DWARF DIE object.
This is a fatal error anyway, just raise an exception.
Fixes#14762
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
Not needed in Python. Detected by check C0325 in pylint3.
Also replace an
if len(tag):
with just
if tag:
Empty strings, byte strings, lists, etc., are falsy in Python.
Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>
Making a clean slate for some pylint CI tests. Only enabling relatively
uncontroversial stuff.
Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>
Dictionaries are iterated in a random order by Python 3.5 and before.
This could have caused "Unstable" CI in PR #13921 and maybe others.
Anyway we want builds to be determimistic by default. Explicit
randomness can be added for better coverage but not by default.
1. When running "make kobj_types_h_target" repeatedly one can observe
that the following .h files keep changing in
build/zephyr/include/generated/:
- kobj-types-enum.h
- otype-to-str.h
- otype-to-size.h
Switching kobjects to OrderedDict makes these 3 .h files deterministic.
2. When running this test repeatedly with CONFIG_USERSPACE=y:
rm build/zephyr/*.gperf && make -C build obj_list
... the dict used for --gperf-output seems to be deterministic, probably
because its keys are all integers (memory addresses). However we can't
take that for granted with Python < 3.6 so out of caution also switch
the output of find_objects() in elf_helper.py to a sorted OrderedDict.
PS: I would normally prefer official Python documentation to
StackOverflow however this one is a good summary and has all the
multiple pointers to the... official Python documentation.
Signed-off-by: Marc Herbert <marc.herbert@intel.com>
SYS_INIT instantiates a device struct, but this is really
just used to run some functions at boot, it does not correspond
to a device driver belonging to a subsystem. Don't put them in
the kernel object table.
These are easy to filter since they are all named with the
_SYS_NAME macro.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
Devices are identified as belonging to a particular subsystem
by looking at device->driver_api.
Print some debug information if this is NULL or points to an
unrecognized API struct.
This is normal in a lot of cases, for example any use of SYS_INIT().
However, for real devices this may be an indication of mis-
configuration.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
For DWARF v2, DW_AT_data_member_location is encoded as a set of operations. The member_offset is in that case a list that starts with an operation (typically DW_OP_plus_uconst), so member_offset[0] is not the offset.
This solves the kernel/poll test (issue #7885)
On some arches like ARC, the member location tag is a list with
the offset and then the member size. We just need the offset.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
If a variable is declared extern first, the name and type
information is stored in a special DW_DIE_variable which
is then referenced by the actual instances via the
tag DW_AT_specification.
We now place extern variable instances in an extern environment
and use this data to fetch the name/type of the instances,
which do not have it (which is why they were being skipped).
As it turns out, the gross hack for the system workqueue was
due to this problem because of the extern declaration in
kernel.h.
Fixes: #6992
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This patch adds a python helper library that encapsulates the ELF
processing being done across multiple scripts. Users of this script
will be converted over in a following patch.
Signed-off-by: Andy Gross <andy.gross@linaro.org>
Wentong Wu
Andrew Boie
Ulf Magnusson
Marc Herbert
Anas Nashif
ruuddw
Andy Gross