Timered operations in a critical section [C] - c

Question

I'm coding in C on Ubuntu.
I need to write a thread called for example "timeredThread" that do some operations in a critical section after N microseconds like the following:
void * timeredThread(void)
{
sleep(TIMEOUT);
pthread_mutex_lock(&mutex);
//operations
pthead_mutex_unlock(&mutex);
}
Also, I need another thread, called for example "timerManager", that can reset the previous timer. My first idea was to create a "timerManager" that kills "timeredThread" and create another one, but this does not work because if I kill "timeredThread" with pthread_cancel() when it's waiting for the mutex I create a deadlock. Deadlock is created because the mutex is in the lock state.
What can I do about it?
Thanks to all in advance.

Answer 1

pthread_mutex_t watchdog_mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t watchdog_cond = PTHREAD_COND_INITIALIZER;
int reset_watchdog = 0;
void reset_watchdog(void) {
pthread_mutex_lock(&watchdog_mutex);
reset_watchdog = 1;
pthread_cond_signal(&watchdog_cond);
pthead_mutex_unlock(&watchdog_mutex);
}
void watchdog(void) {
struct timespec sleep_until = { 0 };
sleep_until.tv_sec = time(NULL) + TIMEOUT;
pthread_mutex_lock(&watchdog_mutex);
// Loop until a time out.
while (!pthread_cond_timedwait(&watchdog_cond, &watchdog_mutex, &sleep_until)) {
if (reset_watchdog) {
sleep_until.tv_sec = time() + TIMEOUT;
reset_watchdog = 0;
}
}
pthead_mutex_unlock(&watchdog_mutex);
// ...
}