/*
* Dependencies here (thus priority inheritance) will NOT be used if
* you specify a timeout value.
*
* Return 0: lock taken, -1: could not find lock, 1: inconsistency -- retry!
*/
int lock_component_take(spdid_t spd, unsigned long lock_id, unsigned short int thd_id)
{
struct meta_lock *ml;
spdid_t spdid = cos_spd_id();
unsigned short int curr = (unsigned short int)cos_get_thd_id();
struct blocked_thds blocked_desc = {.thd_id = curr};
int ret = -1;
ACT_RECORD(ACT_LOCK, spd, lock_id, cos_get_thd_id(), thd_id);
TAKE(spdid);
ml = lock_find(lock_id, spd);
/* tried to access a lock not yet created */
if (!ml) goto error;
assert(!lock_is_thd_blocked(ml, curr));
/* The calling component needs to retry its user-level lock,
* some preemption has caused the generation count to get off,
* i.e. we don't have the most up-to-date view of the
* lock's state */
if (ml->gen_num != generation) {
ml->gen_num = generation;
ret = 1;
goto error;
}
generation++;
/* Note that we are creating the list of blocked threads from
* memory allocated on the individual thread's stacks. */
INIT_LIST(&blocked_desc, next, prev);
ADD_LIST(&ml->b_thds, &blocked_desc, next, prev);
//ml->owner = thd_id;
RELEASE(spdid);
/* printc("cpu %ld: thd %d going to blk waiting for lock %d\n", cos_cpuid(), cos_get_thd_id(), (int)lock_id); */
if (-1 == sched_block(spdid, thd_id)) {
printc("Deadlock including thdids %d -> %d in spd %d, lock id %d.\n",
cos_get_thd_id(), thd_id, spd, (int)lock_id);
debug_print("BUG: Possible deadlock @ ");
assert(0);
if (-1 == sched_block(spdid, 0)) assert(0);
}
if (!EMPTY_LIST(&blocked_desc, next, prev)) BUG();
/*
* OK, this seems ridiculous but here is the rational: Assume
* we are a middle-prio thread, and were just woken by a low
* priority thread. We will preempt that thread when woken,
* and will continue here. If a high priority thread is also
* waiting on the lock, then we would preempt the low priority
* thread while it should wake the high prio thread. With the
* following crit sect will switch to the low prio thread that
* still holds the component lock. See the comments in
* lock_component_release.
*/
//TAKE(spdid);
//RELEASE(spdid);
ACT_RECORD(ACT_WAKEUP, spd, lock_id, cos_get_thd_id(), 0);
ret = 0;
done:
return ret;
error:
RELEASE(spdid);
goto done;
}
/*
* Dependencies here (thus priority inheritance) will NOT be used if
* you specify a timeout value.
*/
int lock_component_take(spdid_t spd, unsigned long lock_id, unsigned short int thd_id, unsigned int microsec)
{
struct meta_lock *ml;
spdid_t spdid = cos_spd_id();
unsigned short int curr = (unsigned short int)cos_get_thd_id();
struct blocked_thds blocked_desc = {.thd_id = curr};
int ret = 0;
// print("thread %d from spd %d locking for %d micrseconds.", curr, spdid, microsec);
ACT_RECORD(ACT_LOCK, spd, lock_id, cos_get_thd_id(), thd_id);
TAKE(spdid);
if (0 == microsec) {
ret = TIMER_EXPIRED;
goto error;
}
ml = lock_find(lock_id, spd);
/* tried to access a lock not yet created */
if (!ml) {
ret = -1;
//print("take wtf%d%d%d", 0,0,0);
goto error;
}
if (lock_is_thd_blocked(ml, curr)) {
prints("lock: lock_is_thd_blocked failed in lock_component_take\n");
goto error;
}
/* The calling component needs to retry its user-level lock,
* some preemption has caused the generation count to get off,
* i.e. we don't have the most up-to-date view of the
* lock's state */
if (ml->gen_num != generation) {
ml->gen_num = generation;
ret = 0;
goto error;
}
generation++;
/* Note that we are creating the list of blocked threads from
* memory allocated on the individual thread's stacks. */
INIT_LIST(&blocked_desc, next, prev);
ADD_LIST(&ml->b_thds, &blocked_desc, next, prev);
blocked_desc.timed = (TIMER_EVENT_INF != microsec);
//ml->owner = thd_id;
RELEASE(spdid);
/* Bypass calling the timed every component if there is an infinite wait */
// assert(TIMER_EVENT_INF == microsec);
// assert(!blocked_desc.timed);
if (TIMER_EVENT_INF == microsec) {
if (-1 == sched_block(spdid, thd_id)) BUG();
if (!EMPTY_LIST(&blocked_desc, next, prev)) BUG();
/*
* OK, this seems ridiculous but here is the rational: Assume
* we are a middle-prio thread, and were just woken by a low
* priority thread. We will preempt that thread when woken,
* and will continue here. If a high priority thread is also
* waiting on the lock, then we would preempt the low priority
* thread while it should wake the high prio thread. With the
* following crit sect will switch to the low prio thread that
* still holds the component lock. See the comments in
* lock_component_release.
*/
//TAKE(spdid);
//RELEASE(spdid);
ACT_RECORD(ACT_WAKEUP, spd, lock_id, cos_get_thd_id(), 0);
ret = 0;
} else {
assert(0);
#ifdef NIL
/* ret here will fall through. We do NOT use the
* dependency here as I can't think through the
* repercussions */
if (-1 == (ret = timed_event_block(spdid, microsec))) return ret;
/*
* We might have woken from a timeout, which means
* that we need to remove this thread from the waiting
* list for the lock.
*/
TAKE(spdid);
ml = lock_find(lock_id, spd);
if (!ml) {
ret = -1;
goto error;
}
REM_LIST(&blocked_desc, next, prev);
RELEASE(spdid);
ACT_RECORD(ACT_WAKEUP, spd, lock_id, cos_get_thd_id(), 0);
/* ret is set to the amnt of time we blocked */
#endif
}
return ret;
error:
RELEASE(spdid);
return ret;
}
