This allows concurrent read access, which are much more common; reducing
potential lock contention and increasing concurrency.
Taking a lock is expensive, and the reader lock is now even more expensive.
An RCU synchronization scheme would reduce the overhead of the readers to
increasing/decreasing an atomic counter.
Thus this should only be an intermediate step until we move towards RCU.
Tested on SITL & Pixracer.
param_t is only used as an offset and we have <1000 params, so an uint16_t
is enough.
This saves roughly 1KB of RAM. We only do that on NuttX because normal
integers have better performance in general.
Previously on amd64, this was even 64bits because it was an uintptr_t.
If param_find() returned PARAM_INVALID, and this was directly passed to
param_get(), param_get_value_ptr() returned null and we read garbage data
(or segfaulted on systems with virtual memory).
On px4fmu-v2, this happened for the param ATT_VIBE_THRESH in sensors.
Because of the recently added parameter scoping, this param got pruned, as
it's defined in attitude_estimator_q.
credits for finding this go to Jeyong Shin (jeyong).
We need to protect access to the param_values array. This is dynamically
allocated and resized (utarray_reserve() calls realloc). If some thread
was iterating the array while another was resizing the array, the first one
would iterate on a freed array, thus accessing invalid memory.
On NuttX this could lead to hardfaults in rare conditions.
Unfortunately we need to initialize the semaphore on startup, by calling
sem_init(). This adds a param_init() method called by every board/config
that uses the params (at least I think I've found all of them)
This patch reorders px4_defines.h to make it more readable (I think)
but more importantly, cleans up the #include <math.h>/<cmath>
and [std::]isfinite stuff.
My main goal was to completely get rid of including math.h/cmath,
because that doesn't really belong in a header that is supposed to
define macro's and is included in almost every source file (if not
all).
I'm not sure what it did before ;) (pun intended), but now it does
the following:
PX4_ISFINITE is only used in C++ code (that was already the case,
but hereby is official; for C code just use 'isfinite()') and is
defined to be std::isfinite, except on __PX4_QURT because that uses
the HEXAGON toolset which (erroneously) defines isfinite as macro.
I would have liked to remove PX4_ISFINITE completely from the code
and just use std::isfinite whereever that is needed, but that would
have required changing the libecl submodule, and at the moment I'm
getting tired of changing submodules... so maybe something for the
future.
Also, all includes of <math.h> or <cmath> have been removed except
for __PX4_NUTTX. Like the HEXAGON toolset NuttX currently defines
isfinite as macro for C++. So, we could have solved this in the
same was as __P4_QURT; but since we can fix NuttX ourselves I chose
to add a kludge to px4_defines.h instead that fixes this problem,
until the time that NuttX can be fixed (again postponing changing
a submodule). The kludge still demands including <cmath>, thus.
After removal of the math header file, it needed to be included
in source files that actually need it, of course.
Finally, I had a look at the math macro's (like M_PI, M_PI_F,
M_DEG_TO_RAD etc). These are sometimes (erroneously) defined in
certain math.h header files (like both, hexagon and nuttx).
This is incorrect: neither the C nor the C++ standard defines
math constants (neither as macro nor otherwise). The "problem"
here was that px4_defines.h defined some of the M_*_F float
constants in terms of the M_* double constant, which are
sometimes not defined either thus. So, I cleaned this up by
defining the M_*_F math constants as float literals in px4_defines.h,
except when they are defined in math.h for that platform.
This means that math.h has to be always included when using those
constants, but well; not much difference there as those files
usually also need/use the macro NAN (which *is* a standard macro
defined by math.h).
Finally finally, DEFAULT_PARAM_FILE was removed as it isn't
used anymore.
All in all I think the resulting px4_defines.h is nice, giving me
much less the feeling of a nearly unmaintainable and over time
slowly growing collection of kludges and hacks.
Since the FRAM and the baro are on the same bus on the Pixracer, we
currently need to lock down everything (instead of just this SPI bus)
for the time when the params are written.
Therefore, we need to keep this locking as short as possible.
This change makes the locking even shorter by moving all param_get and
param_name and param_size calls out of the lock.
Use a struct to contain all the parameters so the ordering in
memory is not machine dependent.
Add number of parameters to the param struct. The struct actually
allows direct accessing by the member name if desired.
Signed-off-by: Mark Charlebois <charlebm@gmail.com>
Changed to enable the posix_sitl_simple target to build and run
param show *
without using a linker script
Signed-off-by: Mark Charlebois <charlebm@gmail.com>
In nuttx the mode parameter to open is not required but in Linux,
and per the POSIX spec, mode is required if the O_CREAT flag is
passed.
The mode flags are different for NuttX and Linux so a new set of
PX4 defines was added:
PX4_O_MODE_777 - read, write, execute for user, group and other
PX4_O_MODE_666 - read, and write for user, group and other
PX4_O_MODE_600 - read, and write for user
Signed-off-by: Mark Charlebois <charlebm@gmail.com>
Set a default path relative to current dir for the posix target.
Running make posixrun will create the required directoroes and then run
mainapp from its build location.
PX4_ROOTFSDIR is set to nothing for nuttx.
Signed-off-by: Mark Charlebois <charlebm@gmail.com>
The existing orb_advert_t use thoughout the code sometimes tries
to treat it as a file descriptor and there are checks for < 0
and ::close calls on orb_advert_t types which is an invalid use
of an object pointer, which is what orb_advert_t really is.
Initially I had changed the -1 initializations to 0 but it was
suggested that this should be nullptr. That was a good recommendation
but the definition of orb_advert_t had to change to void * because
you cannot initialize a uintptr_t as nullptr.
Signed-off-by: Mark Charlebois <charlebm@gmail.com>
The calls to orb_advertise were being mishandled throughout the code.
There were ::close() calls on memory pointers, there were checks
against < 0 when it is a pointer to a object and values larger than
0x7ffffffff are valid. Some places orb_advert_t variables were
being initialized as 0 other places as -1.
The orb_advert_t type was changed to uintptr_t so the pointer value
would not be wrapped as a negative number. This was causing a failure
on ARM.
Tests for < 0 were changed to == 0 since a null pointer is the valid
representation for error, or uninitialized.
Signed-off-by: Mark Charlebois <charlebm@gmail.com>
Unit tests now work. The linux build was failing saving params
because it was using the changes for QuRT that fake out the
filesystem.
Signed-off-by: Mark Charlebois <charlebm@gmail.com>
