Replace use of C11 atomics with atomic utils. This fixes
> error: address argument to atomic operation must be a pointer to a
> trivially-copyable type ('_Atomic(int) *' invalid)
error when compiling on AVR with LLVM.
Place a verbatim copy of `_mutex_lock()` as `static` in `xtimer`, so internal
mutex function can be optimized one step at a time without breaking `xtimer`.
Replace direct accesses to sched_active_thread and sched_active_pid with
the helper functions thread_getpid() and thread_get_active(). This serves
two purposes:
1. It makes accidental writes to those variable from outside core less likely.
2. Casting off the volatile qualifier is now well contained to those two
functions
This function tries to remove the thread from a mutex waiting queue.
The value pointed to by unlocked will be set to 1 if the thread was removed from the waiting queue otherwise 0.
Handling timeout smaller than XTIMER_BACKOFF (the timer spins) when the mutex is already locked.
This fixes the test tests/xtimer_mutex_lock_timeout/main.c:mutex_timeout_spin_locked.
Prevent a possible race condition when _mutex_timeout fires just after the
mutex was locked but before the xtimer was removed
The flow
int xtimer_mutex_lock_timeout(mutex_t *mutex, uint64_t timeout) {
...
mutex_lock(mutex);
/* mutex locked */
/* _mutex_timeout fires and tries to remove thread from mutex queue */
/* DEBUG: simulate callback call between lock and remove */
xtimer_spin(xtimer_ticks_from_usec(timeout*2));
xtimer_remove(&t);
...
}
if xtimer_set spins the callback is executed in the thread context.
comment to explain irq_disable
and when this line could be removed
(when xtimer stops executing the callback funtion from thread context)
- more robust underflow protection in xtimer_usleep_until()
- use relative target in xtimer_spin()
- honour reference in isr when spinning until timer target
- add XTIMER_BACKOFF to xtimer_spin_until() target when backing off in
_timer_set_absolute()
- doxygen updates
