#include <stdio.h>
#include <algorithm>
+#include <mutex>
#include "model.h"
#include "action.h"
#include "cyclegraph.h"
#include "promise.h"
#include "datarace.h"
-#include "mutex.h"
+#include "threads-model.h"
#define INITIAL_THREAD_ID 0
thread_map(new HashTable<int, Thread *, int>()),
obj_map(new HashTable<const void *, action_list_t, uintptr_t, 4>()),
lock_waiters_map(new HashTable<const void *, action_list_t, uintptr_t, 4>()),
+ condvar_waiters_map(new HashTable<const void *, action_list_t, uintptr_t, 4>()),
obj_thrd_map(new HashTable<void *, std::vector<action_list_t>, uintptr_t, 4 >()),
- promises(new std::vector<Promise *>()),
- futurevalues(new std::vector<struct PendingFutureValue>()),
- pending_acq_rel_seq(new std::vector<ModelAction *>()),
- thrd_last_action(new std::vector<ModelAction *>(1)),
+ promises(new std::vector< Promise *, SnapshotAlloc<Promise *> >()),
+ futurevalues(new std::vector< struct PendingFutureValue, SnapshotAlloc<struct PendingFutureValue> >()),
+ pending_rel_seqs(new std::vector< struct release_seq *, SnapshotAlloc<struct release_seq *> >()),
+ thrd_last_action(new std::vector< ModelAction *, SnapshotAlloc<ModelAction *> >(1)),
node_stack(new NodeStack()),
mo_graph(new CycleGraph()),
failed_promise(false),
priv = (struct model_snapshot_members *)calloc(1, sizeof(*priv));
/* First thread created will have id INITIAL_THREAD_ID */
priv->next_thread_id = INITIAL_THREAD_ID;
+
+ /* Initialize a model-checker thread, for special ModelActions */
+ model_thread = new Thread(get_next_id());
+ thread_map->put(id_to_int(model_thread->get_id()), model_thread);
}
/** @brief Destructor */
ModelChecker::~ModelChecker()
{
- for (int i = 0; i < get_num_threads(); i++)
+ for (unsigned int i = 0; i < get_num_threads(); i++)
delete thread_map->get(i);
delete thread_map;
delete obj_thrd_map;
delete obj_map;
delete lock_waiters_map;
+ delete condvar_waiters_map;
delete action_trace;
for (unsigned int i = 0; i < promises->size(); i++)
delete (*promises)[i];
delete promises;
- delete pending_acq_rel_seq;
+ delete pending_rel_seqs;
delete thrd_last_action;
delete node_stack;
}
/** @return the number of user threads created during this execution */
-int ModelChecker::get_num_threads()
+unsigned int ModelChecker::get_num_threads()
{
return priv->next_thread_id;
}
+/** @return The currently executing Thread. */
+Thread * ModelChecker::get_current_thread()
+{
+ return scheduler->get_current_thread();
+}
+
/** @return a sequence number for a new ModelAction */
modelclock_t ModelChecker::get_next_seq_num()
{
return ++priv->used_sequence_numbers;
}
+Node * ModelChecker::get_curr_node() {
+ return node_stack->get_head();
+}
+
/**
* @brief Choose the next thread to execute.
*
earliest_diverge=diverge;
Node *nextnode = next->get_node();
+ Node *prevnode = nextnode->get_parent();
+ scheduler->update_sleep_set(prevnode);
+
/* Reached divergence point */
- if (nextnode->increment_promise()) {
+ if (nextnode->increment_misc()) {
+ /* The next node will try to satisfy a different misc_index values. */
+ tid = next->get_tid();
+ node_stack->pop_restofstack(2);
+ } else if (nextnode->increment_promise()) {
/* The next node will try to satisfy a different set of promises. */
tid = next->get_tid();
node_stack->pop_restofstack(2);
/* The next node will try to read from a different future value. */
tid = next->get_tid();
node_stack->pop_restofstack(2);
+ } else if (nextnode->increment_relseq_break()) {
+ /* The next node will try to resolve a release sequence differently */
+ tid = next->get_tid();
+ node_stack->pop_restofstack(2);
} else {
/* Make a different thread execute for next step */
- Node *node = nextnode->get_parent();
- tid = node->get_next_backtrack();
+ scheduler->add_sleep(thread_map->get(id_to_int(next->get_tid())));
+ tid = prevnode->get_next_backtrack();
+ /* Make sure the backtracked thread isn't sleeping. */
node_stack->pop_restofstack(1);
if (diverge==earliest_diverge) {
- earliest_diverge=node->get_action();
+ earliest_diverge=prevnode->get_action();
}
}
+ /* The correct sleep set is in the parent node. */
+ execute_sleep_set();
+
DEBUG("*** Divergence point ***\n");
diverge = NULL;
} else {
tid = next->get_tid();
}
- DEBUG("*** ModelChecker chose next thread = %d ***\n", tid);
+ DEBUG("*** ModelChecker chose next thread = %d ***\n", id_to_int(tid));
ASSERT(tid != THREAD_ID_T_NONE);
return thread_map->get(id_to_int(tid));
}
+/**
+ * We need to know what the next actions of all threads in the sleep
+ * set will be. This method computes them and stores the actions at
+ * the corresponding thread object's pending action.
+ */
+
+void ModelChecker::execute_sleep_set() {
+ for(unsigned int i=0;i<get_num_threads();i++) {
+ thread_id_t tid=int_to_id(i);
+ Thread *thr=get_thread(tid);
+ if ( scheduler->get_enabled(thr) == THREAD_SLEEP_SET ) {
+ thr->set_state(THREAD_RUNNING);
+ scheduler->next_thread(thr);
+ Thread::swap(&system_context, thr);
+ priv->current_action->set_sleep_flag();
+ thr->set_pending(priv->current_action);
+ }
+ }
+ priv->current_action = NULL;
+}
+
+void ModelChecker::wake_up_sleeping_actions(ModelAction * curr) {
+ for(unsigned int i=0;i<get_num_threads();i++) {
+ thread_id_t tid=int_to_id(i);
+ Thread *thr=get_thread(tid);
+ if ( scheduler->get_enabled(thr) == THREAD_SLEEP_SET ) {
+ ModelAction *pending_act=thr->get_pending();
+ if ((!curr->is_rmwr())&&pending_act->could_synchronize_with(curr)) {
+ //Remove this thread from sleep set
+ scheduler->remove_sleep(thr);
+ }
+ }
+ }
+}
+
/**
* Queries the model-checker for more executions to explore and, if one
* exists, resets the model-checker state to execute a new execution.
DBG();
num_executions++;
+
if (isfinalfeasible()) {
printf("Earliest divergence point since last feasible execution:\n");
if (earliest_diverge)
- earliest_diverge->print(false);
+ earliest_diverge->print();
else
printf("(Not set)\n");
num_feasible_executions++;
}
- if (isfinalfeasible() || DBG_ENABLED())
+ DEBUG("Number of acquires waiting on pending release sequences: %zu\n",
+ pending_rel_seqs->size());
+
+
+ if (isfinalfeasible() || (params.bound != 0 && priv->used_sequence_numbers > params.bound ) || DBG_ENABLED() )
print_summary();
if ((diverge = get_next_backtrack()) == NULL)
action_list_t::reverse_iterator rit;
for (rit = list->rbegin(); rit != list->rend(); rit++) {
ModelAction *prev = *rit;
- if (act->is_synchronizing(prev))
+ if (prev->could_synchronize_with(act))
return prev;
}
break;
}
break;
}
+ case ATOMIC_WAIT: {
+ /* linear search: from most recent to oldest */
+ action_list_t *list = obj_map->get_safe_ptr(act->get_location());
+ action_list_t::reverse_iterator rit;
+ for (rit = list->rbegin(); rit != list->rend(); rit++) {
+ ModelAction *prev = *rit;
+ if (!act->same_thread(prev)&&prev->is_failed_trylock())
+ return prev;
+ if (!act->same_thread(prev)&&prev->is_notify())
+ return prev;
+ }
+ break;
+ }
+
+ case ATOMIC_NOTIFY_ALL:
+ case ATOMIC_NOTIFY_ONE: {
+ /* linear search: from most recent to oldest */
+ action_list_t *list = obj_map->get_safe_ptr(act->get_location());
+ action_list_t::reverse_iterator rit;
+ for (rit = list->rbegin(); rit != list->rend(); rit++) {
+ ModelAction *prev = *rit;
+ if (!act->same_thread(prev)&&prev->is_wait())
+ return prev;
+ }
+ break;
+ }
default:
break;
}
return NULL;
}
-/** This method find backtracking points where we should try to
+/** This method finds backtracking points where we should try to
* reorder the parameter ModelAction against.
*
* @param the ModelAction to find backtracking points for.
for(int i = low_tid; i < high_tid; i++) {
thread_id_t tid = int_to_id(i);
- if (!node->is_enabled(tid))
- continue;
+ /* Don't backtrack into a point where the thread is disabled or sleeping. */
+ if (node->get_enabled_array()[i]!=THREAD_ENABLED)
+ continue;
+
/* Check if this has been explored already */
if (node->has_been_explored(tid))
continue;
if (unfair)
continue;
}
-
/* Cache the latest backtracking point */
if (!priv->next_backtrack || *prev > *priv->next_backtrack)
priv->next_backtrack = prev;
if (!node->set_backtrack(tid))
continue;
DEBUG("Setting backtrack: conflict = %d, instead tid = %d\n",
- prev->get_tid(), t->get_id());
+ id_to_int(prev->get_tid()),
+ id_to_int(t->get_id()));
if (DBG_ENABLED()) {
prev->print();
act->print();
*/
bool ModelChecker::process_read(ModelAction *curr, bool second_part_of_rmw)
{
- uint64_t value;
+ uint64_t value = VALUE_NONE;
bool updated = false;
while (true) {
const ModelAction *reads_from = curr->get_node()->get_read_from();
curr->read_from(reads_from);
mo_graph->commitChanges();
+ mo_check_promises(curr->get_tid(), reads_from);
+
updated |= r_status;
} else if (!second_part_of_rmw) {
/* Read from future value */
* @return True if synchronization was updated; false otherwise
*/
bool ModelChecker::process_mutex(ModelAction *curr) {
- std::mutex *mutex = (std::mutex *)curr->get_location();
- struct std::mutex_state *state = mutex->get_state();
+ std::mutex *mutex=NULL;
+ struct std::mutex_state *state=NULL;
+
+ if (curr->is_trylock() || curr->is_lock() || curr->is_unlock()) {
+ mutex = (std::mutex *)curr->get_location();
+ state = mutex->get_state();
+ } else if(curr->is_wait()) {
+ mutex = (std::mutex *)curr->get_value();
+ state = mutex->get_state();
+ }
+
switch (curr->get_type()) {
case ATOMIC_TRYLOCK: {
bool success = !state->islocked;
waiters->clear();
break;
}
+ case ATOMIC_WAIT: {
+ //unlock the lock
+ state->islocked = false;
+ //wake up the other threads
+ action_list_t *waiters = lock_waiters_map->get_safe_ptr((void *) curr->get_value());
+ //activate all the waiting threads
+ for (action_list_t::iterator rit = waiters->begin(); rit != waiters->end(); rit++) {
+ scheduler->wake(get_thread(*rit));
+ }
+ waiters->clear();
+ //check whether we should go to sleep or not...simulate spurious failures
+ if (curr->get_node()->get_misc()==0) {
+ condvar_waiters_map->get_safe_ptr(curr->get_location())->push_back(curr);
+ //disable us
+ scheduler->sleep(get_current_thread());
+ }
+ break;
+ }
+ case ATOMIC_NOTIFY_ALL: {
+ action_list_t *waiters = condvar_waiters_map->get_safe_ptr(curr->get_location());
+ //activate all the waiting threads
+ for (action_list_t::iterator rit = waiters->begin(); rit != waiters->end(); rit++) {
+ scheduler->wake(get_thread(*rit));
+ }
+ waiters->clear();
+ break;
+ }
+ case ATOMIC_NOTIFY_ONE: {
+ action_list_t *waiters = condvar_waiters_map->get_safe_ptr(curr->get_location());
+ int wakeupthread=curr->get_node()->get_misc();
+ action_list_t::iterator it = waiters->begin();
+ advance(it, wakeupthread);
+ scheduler->wake(get_thread(*it));
+ waiters->erase(it);
+ break;
+ }
+
default:
ASSERT(0);
}
if (promises->size() == 0) {
for (unsigned int i = 0; i < futurevalues->size(); i++) {
struct PendingFutureValue pfv = (*futurevalues)[i];
- if (pfv.act->get_node()->add_future_value(pfv.value, pfv.expiration) &&
+ //Do more ambitious checks now that mo is more complete
+ if (mo_may_allow(pfv.writer, pfv.act)&&
+ pfv.act->get_node()->add_future_value(pfv.writer->get_value(), pfv.writer->get_seq_number()+params.maxfuturedelay) &&
(!priv->next_backtrack || *pfv.act > *priv->next_backtrack))
priv->next_backtrack = pfv.act;
}
}
mo_graph->commitChanges();
+ mo_check_promises(curr->get_tid(), curr);
+
get_thread(curr)->set_return_value(VALUE_NONE);
return updated_mod_order || updated_promises;
}
break;
}
case THREAD_JOIN: {
- Thread *waiting, *blocking;
- waiting = get_thread(curr);
- blocking = (Thread *)curr->get_location();
- if (!blocking->is_complete()) {
- blocking->push_wait_list(curr);
- scheduler->sleep(waiting);
- } else {
- do_complete_join(curr);
- updated = true; /* trigger rel-seq checks */
- }
+ Thread *blocking = (Thread *)curr->get_location();
+ ModelAction *act = get_last_action(blocking->get_id());
+ curr->synchronize_with(act);
+ updated = true; /* trigger rel-seq checks */
break;
}
case THREAD_FINISH: {
Thread *th = get_thread(curr);
while (!th->wait_list_empty()) {
ModelAction *act = th->pop_wait_list();
- Thread *wake = get_thread(act);
- scheduler->wake(wake);
- do_complete_join(act);
- updated = true; /* trigger rel-seq checks */
+ scheduler->wake(get_thread(act));
}
th->complete();
updated = true; /* trigger rel-seq checks */
break;
}
case THREAD_START: {
- check_promises(NULL, curr->get_cv());
+ check_promises(curr->get_tid(), NULL, curr->get_cv());
break;
}
default:
return updated;
}
+/**
+ * @brief Process the current action for release sequence fixup activity
+ *
+ * Performs model-checker release sequence fixups for the current action,
+ * forcing a single pending release sequence to break (with a given, potential
+ * "loose" write) or to complete (i.e., synchronize). If a pending release
+ * sequence forms a complete release sequence, then we must perform the fixup
+ * synchronization, mo_graph additions, etc.
+ *
+ * @param curr The current action; must be a release sequence fixup action
+ * @param work_queue The work queue to which to add work items as they are
+ * generated
+ */
+void ModelChecker::process_relseq_fixup(ModelAction *curr, work_queue_t *work_queue)
+{
+ const ModelAction *write = curr->get_node()->get_relseq_break();
+ struct release_seq *sequence = pending_rel_seqs->back();
+ pending_rel_seqs->pop_back();
+ ASSERT(sequence);
+ ModelAction *acquire = sequence->acquire;
+ const ModelAction *rf = sequence->rf;
+ const ModelAction *release = sequence->release;
+ ASSERT(acquire);
+ ASSERT(release);
+ ASSERT(rf);
+ ASSERT(release->same_thread(rf));
+
+ if (write == NULL) {
+ /**
+ * @todo Forcing a synchronization requires that we set
+ * modification order constraints. For instance, we can't allow
+ * a fixup sequence in which two separate read-acquire
+ * operations read from the same sequence, where the first one
+ * synchronizes and the other doesn't. Essentially, we can't
+ * allow any writes to insert themselves between 'release' and
+ * 'rf'
+ */
+
+ /* Must synchronize */
+ if (!acquire->synchronize_with(release)) {
+ set_bad_synchronization();
+ return;
+ }
+ /* Re-check all pending release sequences */
+ work_queue->push_back(CheckRelSeqWorkEntry(NULL));
+ /* Re-check act for mo_graph edges */
+ work_queue->push_back(MOEdgeWorkEntry(acquire));
+
+ /* propagate synchronization to later actions */
+ action_list_t::reverse_iterator rit = action_trace->rbegin();
+ for (; (*rit) != acquire; rit++) {
+ ModelAction *propagate = *rit;
+ if (acquire->happens_before(propagate)) {
+ propagate->synchronize_with(acquire);
+ /* Re-check 'propagate' for mo_graph edges */
+ work_queue->push_back(MOEdgeWorkEntry(propagate));
+ }
+ }
+ } else {
+ /* Break release sequence with new edges:
+ * release --mo--> write --mo--> rf */
+ mo_graph->addEdge(release, write);
+ mo_graph->addEdge(write, rf);
+ }
+
+ /* See if we have realized a data race */
+ if (checkDataRaces())
+ set_assert();
+}
+
/**
* Initialize the current action by performing one or more of the following
* actions, as appropriate: merging RMWR and RMWC/RMW actions, stepping forward
*/
if (newcurr->is_write())
compute_promises(newcurr);
+ else if (newcurr->is_relseq_fixup())
+ compute_relseq_breakwrites(newcurr);
+ else if (newcurr->is_wait())
+ newcurr->get_node()->set_misc_max(2);
+ else if (newcurr->is_notify_one()) {
+ newcurr->get_node()->set_misc_max(condvar_waiters_map->get_safe_ptr(newcurr->get_location())->size());
+ }
}
return newcurr;
}
/**
- * This method checks whether a model action is enabled at the given point.
- * At this point, it checks whether a lock operation would be successful at this point.
- * If not, it puts the thread in a waiter list.
+ * @brief Check whether a model action is enabled.
+ *
+ * Checks whether a lock or join operation would be successful (i.e., is the
+ * lock already locked, or is the joined thread already complete). If not, put
+ * the action in a waiter list.
+ *
* @param curr is the ModelAction to check whether it is enabled.
* @return a bool that indicates whether the action is enabled.
*/
lock_waiters_map->get_safe_ptr(curr->get_location())->push_back(curr);
return false;
}
+ } else if (curr->get_type() == THREAD_JOIN) {
+ Thread *blocking = (Thread *)curr->get_location();
+ if (!blocking->is_complete()) {
+ blocking->push_wait_list(curr);
+ return false;
+ }
}
return true;
Thread * ModelChecker::check_current_action(ModelAction *curr)
{
ASSERT(curr);
-
bool second_part_of_rmw = curr->is_rmwc() || curr->is_rmw();
if (!check_action_enabled(curr)) {
/* Make the execution look like we chose to run this action
- * much later, when a lock is actually available to release */
+ * much later, when a lock/join can succeed */
get_current_thread()->set_pending(curr);
scheduler->sleep(get_current_thread());
return get_next_thread(NULL);
ModelAction *newcurr = initialize_curr_action(curr);
+ wake_up_sleeping_actions(newcurr);
+
/* Add the action to lists before any other model-checking tasks */
if (!second_part_of_rmw)
add_action_to_lists(newcurr);
/* Initialize work_queue with the "current action" work */
work_queue_t work_queue(1, CheckCurrWorkEntry(curr));
-
while (!work_queue.empty()) {
WorkQueueEntry work = work_queue.front();
work_queue.pop_front();
if (act->is_mutex_op() && process_mutex(act))
update_all = true;
+ if (act->is_relseq_fixup())
+ process_relseq_fixup(curr, &work_queue);
+
if (update_all)
work_queue.push_back(CheckRelSeqWorkEntry(NULL));
else if (update)
}
check_curr_backtracking(curr);
-
set_backtracking(curr);
-
return get_next_thread(curr);
}
-/**
- * Complete a THREAD_JOIN operation, by synchronizing with the THREAD_FINISH
- * operation from the Thread it is joining with. Must be called after the
- * completion of the Thread in question.
- * @param join The THREAD_JOIN action
- */
-void ModelChecker::do_complete_join(ModelAction *join)
-{
- Thread *blocking = (Thread *)join->get_location();
- ModelAction *act = get_last_action(blocking->get_id());
- join->synchronize_with(act);
-}
-
void ModelChecker::check_curr_backtracking(ModelAction * curr) {
Node *currnode = curr->get_node();
Node *parnode = currnode->get_parent();
if ((!parnode->backtrack_empty() ||
+ !currnode->misc_empty() ||
!currnode->read_from_empty() ||
!currnode->future_value_empty() ||
- !currnode->promise_empty())
+ !currnode->promise_empty() ||
+ !currnode->relseq_break_empty())
&& (!priv->next_backtrack ||
*curr > *priv->next_backtrack)) {
priv->next_backtrack = curr;
/** @return whether the current partial trace must be a prefix of a
* feasible trace. */
bool ModelChecker::isfeasibleprefix() {
- return promises->size() == 0 && pending_acq_rel_seq->size() == 0;
+ return promises->size() == 0 && pending_rel_seqs->size() == 0;
}
/** @return whether the current partial trace is feasible. */
/** Close out a RMWR by converting previous RMWR into a RMW or READ. */
ModelAction * ModelChecker::process_rmw(ModelAction *act) {
- int tid = id_to_int(act->get_tid());
- ModelAction *lastread = get_last_action(tid);
+ ModelAction *lastread = get_last_action(act->get_tid());
lastread->process_rmw(act);
if (act->is_rmw() && lastread->get_reads_from()!=NULL) {
mo_graph->addRMWEdge(lastread->get_reads_from(), lastread);
}
} else {
const ModelAction *prevreadfrom = act->get_reads_from();
- if (prevreadfrom != NULL && rf != prevreadfrom) {
+ //if the previous read is unresolved, keep going...
+ if (prevreadfrom == NULL)
+ continue;
+
+ if (rf != prevreadfrom) {
mo_graph->addEdge(prevreadfrom, rf);
added = true;
}
ModelAction *act = *rit;
if (act == curr) {
/*
- * If RMW, we already have all relevant edges,
- * so just skip to next thread.
- * If normal write, we need to look at earlier
- * actions, so continue processing list.
+ * 1) If RMW and it actually read from something, then we
+ * already have all relevant edges, so just skip to next
+ * thread.
+ *
+ * 2) If RMW and it didn't read from anything, we should
+ * whatever edge we can get to speed up convergence.
+ *
+ * 3) If normal write, we need to look at earlier actions, so
+ * continue processing list.
*/
- if (curr->is_rmw())
- break;
- else
+ if (curr->is_rmw()) {
+ if (curr->get_reads_from()!=NULL)
+ break;
+ else
+ continue;
+ } else
continue;
}
*/
if (act->is_write())
mo_graph->addEdge(act, curr);
- else if (act->is_read() && act->get_reads_from() != NULL)
+ else if (act->is_read()) {
+ //if previous read accessed a null, just keep going
+ if (act->get_reads_from() == NULL)
+ continue;
mo_graph->addEdge(act->get_reads_from(), curr);
+ }
added = true;
break;
- } else if (act->is_read() && !act->is_synchronizing(curr) &&
+ } else if (act->is_read() && !act->could_synchronize_with(curr) &&
!act->same_thread(curr)) {
/* We have an action that:
(1) did not happen before us
(3) cannot synchronize with us
(4) is in a different thread
=>
- that read could potentially read from our write.
+ that read could potentially read from our write. Note that
+ these checks are overly conservative at this point, we'll
+ do more checks before actually removing the
+ pendingfuturevalue.
+
*/
if (thin_air_constraint_may_allow(curr, act)) {
if (isfeasible() ||
(curr->is_rmw() && act->is_rmw() && curr->get_reads_from() == act->get_reads_from() && isfeasibleotherthanRMW())) {
- struct PendingFutureValue pfv = {curr->get_value(),curr->get_seq_number()+params.maxfuturedelay,act};
+ struct PendingFutureValue pfv = {curr,act};
futurevalues->push_back(pfv);
}
}
return true;
}
+/**
+ * Arbitrary reads from the future are not allowed. Section 29.3 part 9 places
+ * some constraints. This method checks one the following constraint (others
+ * require compiler support):
+ *
+ * If X --hb-> Y --mo-> Z, then X should not read from Z.
+ */
+bool ModelChecker::mo_may_allow(const ModelAction *writer, const ModelAction *reader)
+{
+ std::vector<action_list_t> *thrd_lists = obj_thrd_map->get_safe_ptr(reader->get_location());
+ unsigned int i;
+
+ /* Iterate over all threads */
+ for (i = 0; i < thrd_lists->size(); i++) {
+ ModelAction *write_after_read = NULL;
+
+ /* Iterate over actions in thread, starting from most recent */
+ action_list_t *list = &(*thrd_lists)[i];
+ action_list_t::reverse_iterator rit;
+ for (rit = list->rbegin(); rit != list->rend(); rit++) {
+ ModelAction *act = *rit;
+
+ if (!reader->happens_before(act))
+ break;
+ else if (act->is_write())
+ write_after_read = act;
+ }
+
+ if (write_after_read && mo_graph->checkReachable(write_after_read, writer))
+ return false;
+ }
+
+ return true;
+}
+
/**
* Finds the head(s) of the release sequence(s) containing a given ModelAction.
* The ModelAction under consideration is expected to be taking part in
* "returns" two pieces of data: a pass-by-reference vector of @a release_heads
* and a boolean representing certainty.
*
- * @todo Finish lazy updating, when promises are fulfilled in the future
* @param rf The action that might be part of a release sequence. Must be a
* write.
- * @param release_heads A pass-by-reference style return parameter. After
+ * @param release_heads A pass-by-reference style return parameter. After
* execution of this function, release_heads will contain the heads of all the
- * relevant release sequences, if any exists
+ * relevant release sequences, if any exists with certainty
+ * @param pending A pass-by-reference style return parameter which is only used
+ * when returning false (i.e., uncertain). Returns most information regarding
+ * an uncertain release sequence, including any write operations that might
+ * break the sequence.
* @return true, if the ModelChecker is certain that release_heads is complete;
* false otherwise
*/
-bool ModelChecker::release_seq_head(const ModelAction *rf, rel_heads_list_t *release_heads) const
+bool ModelChecker::release_seq_heads(const ModelAction *rf,
+ rel_heads_list_t *release_heads,
+ struct release_seq *pending) const
{
/* Only check for release sequences if there are no cycles */
if (mo_graph->checkForCycles())
};
if (!rf) {
/* read from future: need to settle this later */
+ pending->rf = NULL;
return false; /* incomplete */
}
ASSERT(rf->same_thread(release));
+ pending->writes.clear();
+
bool certain = true;
for (unsigned int i = 0; i < thrd_lists->size(); i++) {
if (id_to_int(rf->get_tid()) == (int)i)
bool future_ordered = false;
ModelAction *last = get_last_action(int_to_id(i));
- if (last && (rf->happens_before(last) ||
- last->get_type() == THREAD_FINISH))
+ Thread *th = get_thread(int_to_id(i));
+ if ((last && rf->happens_before(last)) ||
+ !scheduler->is_enabled(th) ||
+ th->is_complete())
future_ordered = true;
+ ASSERT(!th->is_model_thread() || future_ordered);
+
for (rit = list->rbegin(); rit != list->rend(); rit++) {
const ModelAction *act = *rit;
/* Reach synchronization -> this thread is complete */
continue;
}
- /* Only writes can break release sequences */
- if (!act->is_write())
+ /* Only non-RMW writes can break release sequences */
+ if (!act->is_write() || act->is_rmw())
continue;
/* Check modification order */
/* release --mo-> act --mo--> rf */
return true; /* complete */
}
+ /* act may break release sequence */
+ pending->writes.push_back(act);
certain = false;
}
if (!future_ordered)
- return false; /* This thread is uncertain */
+ certain = false; /* This thread is uncertain */
}
- if (certain)
+ if (certain) {
release_heads->push_back(release);
+ pending->writes.clear();
+ } else {
+ pending->release = release;
+ pending->rf = rf;
+ }
return certain;
}
* @param act The 'acquire' action that may read from a release sequence
* @param release_heads A pass-by-reference return parameter. Will be filled
* with the head(s) of the release sequence(s), if they exists with certainty.
- * @see ModelChecker::release_seq_head
+ * @see ModelChecker::release_seq_heads
*/
void ModelChecker::get_release_seq_heads(ModelAction *act, rel_heads_list_t *release_heads)
{
const ModelAction *rf = act->get_reads_from();
- bool complete;
- complete = release_seq_head(rf, release_heads);
- if (!complete) {
+ struct release_seq *sequence = (struct release_seq *)snapshot_calloc(1, sizeof(struct release_seq));
+ sequence->acquire = act;
+
+ if (!release_seq_heads(rf, release_heads, sequence)) {
/* add act to 'lazy checking' list */
- pending_acq_rel_seq->push_back(act);
+ pending_rel_seqs->push_back(sequence);
+ } else {
+ snapshot_free(sequence);
}
}
bool ModelChecker::resolve_release_sequences(void *location, work_queue_t *work_queue)
{
bool updated = false;
- std::vector<ModelAction *>::iterator it = pending_acq_rel_seq->begin();
- while (it != pending_acq_rel_seq->end()) {
- ModelAction *act = *it;
+ std::vector< struct release_seq *, SnapshotAlloc<struct release_seq *> >::iterator it = pending_rel_seqs->begin();
+ while (it != pending_rel_seqs->end()) {
+ struct release_seq *pending = *it;
+ ModelAction *act = pending->acquire;
/* Only resolve sequences on the given location, if provided */
if (location && act->get_location() != location) {
const ModelAction *rf = act->get_reads_from();
rel_heads_list_t release_heads;
bool complete;
- complete = release_seq_head(rf, &release_heads);
+ complete = release_seq_heads(rf, &release_heads, pending);
for (unsigned int i = 0; i < release_heads.size(); i++) {
if (!act->has_synchronized_with(release_heads[i])) {
if (act->synchronize_with(release_heads[i]))
}
}
}
- if (complete)
- it = pending_acq_rel_seq->erase(it);
- else
+ if (complete) {
+ it = pending_rel_seqs->erase(it);
+ snapshot_free(pending);
+ } else {
it++;
+ }
}
// If we resolved promises or data races, see if we have realized a data race.
if ((int)thrd_last_action->size() <= tid)
thrd_last_action->resize(get_num_threads());
(*thrd_last_action)[tid] = act;
+
+ if (act->is_wait()) {
+ void *mutex_loc=(void *) act->get_value();
+ obj_map->get_safe_ptr(mutex_loc)->push_back(act);
+
+ std::vector<action_list_t> *vec = obj_thrd_map->get_safe_ptr(mutex_loc);
+ if (tid >= (int)vec->size())
+ vec->resize(priv->next_thread_id);
+ (*vec)[tid].push_back(act);
+
+ if ((int)thrd_last_action->size() <= tid)
+ thrd_last_action->resize(get_num_threads());
+ (*thrd_last_action)[tid] = act;
+ }
}
/**
/* Find: max({i in dom(S) | isUnlock(t_i) && samevar(t_i, t)}) */
action_list_t::reverse_iterator rit;
for (rit = list->rbegin(); rit != list->rend(); rit++)
- if ((*rit)->is_unlock())
+ if ((*rit)->is_unlock() || (*rit)->is_wait())
return *rit;
return NULL;
}
bool ModelChecker::resolve_promises(ModelAction *write)
{
bool resolved = false;
+ std::vector< thread_id_t, ModelAlloc<thread_id_t> > threads_to_check;
for (unsigned int i = 0, promise_index = 0; promise_index < promises->size(); i++) {
Promise *promise = (*promises)[promise_index];
post_r_modification_order(read, write);
//Make sure the promise's value matches the write's value
ASSERT(promise->get_value() == write->get_value());
-
+ delete(promise);
+
promises->erase(promises->begin() + promise_index);
+ threads_to_check.push_back(read->get_tid());
+
resolved = true;
} else
promise_index++;
}
+
+ //Check whether reading these writes has made threads unable to
+ //resolve promises
+
+ for(unsigned int i=0;i<threads_to_check.size();i++)
+ mo_check_promises(threads_to_check[i], write);
+
return resolved;
}
const ModelAction *act = promise->get_action();
if (!act->happens_before(curr) &&
act->is_read() &&
- !act->is_synchronizing(curr) &&
+ !act->could_synchronize_with(curr) &&
!act->same_thread(curr) &&
+ act->get_location() == curr->get_location() &&
promise->get_value() == curr->get_value()) {
curr->get_node()->set_promise(i);
}
}
/** Checks promises in response to change in ClockVector Threads. */
-void ModelChecker::check_promises(ClockVector *old_cv, ClockVector *merge_cv)
+void ModelChecker::check_promises(thread_id_t tid, ClockVector *old_cv, ClockVector *merge_cv)
{
for (unsigned int i = 0; i < promises->size(); i++) {
Promise *promise = (*promises)[i];
const ModelAction *act = promise->get_action();
if ((old_cv == NULL || !old_cv->synchronized_since(act)) &&
merge_cv->synchronized_since(act)) {
- //This thread is no longer able to send values back to satisfy the promise
- int num_synchronized_threads = promise->increment_threads();
- if (num_synchronized_threads == get_num_threads()) {
+ if (promise->increment_threads(tid)) {
//Promise has failed
failed_promise = true;
return;
}
}
+/** Checks promises in response to addition to modification order for threads.
+ * Definitions:
+ * pthread is the thread that performed the read that created the promise
+ *
+ * pread is the read that created the promise
+ *
+ * pwrite is either the first write to same location as pread by
+ * pthread that is sequenced after pread or the value read by the
+ * first read to the same lcoation as pread by pthread that is
+ * sequenced after pread..
+ *
+ * 1. If tid=pthread, then we check what other threads are reachable
+ * through the mode order starting with pwrite. Those threads cannot
+ * perform a write that will resolve the promise due to modification
+ * order constraints.
+ *
+ * 2. If the tid is not pthread, we check whether pwrite can reach the
+ * action write through the modification order. If so, that thread
+ * cannot perform a future write that will resolve the promise due to
+ * modificatin order constraints.
+ *
+ * @parem tid The thread that either read from the model action
+ * write, or actually did the model action write.
+ *
+ * @parem write The ModelAction representing the relevant write.
+ */
+
+void ModelChecker::mo_check_promises(thread_id_t tid, const ModelAction *write) {
+ void * location = write->get_location();
+ for (unsigned int i = 0; i < promises->size(); i++) {
+ Promise *promise = (*promises)[i];
+ const ModelAction *act = promise->get_action();
+
+ //Is this promise on the same location?
+ if ( act->get_location() != location )
+ continue;
+
+ //same thread as the promise
+ if ( act->get_tid()==tid ) {
+
+ //do we have a pwrite for the promise, if not, set it
+ if (promise->get_write() == NULL ) {
+ promise->set_write(write);
+ //The pwrite cannot happen before the promise
+ if (write->happens_before(act) && (write != act)) {
+ failed_promise = true;
+ return;
+ }
+ }
+ if (mo_graph->checkPromise(write, promise)) {
+ failed_promise = true;
+ return;
+ }
+ }
+
+ //Don't do any lookups twice for the same thread
+ if (promise->has_sync_thread(tid))
+ continue;
+
+ if (mo_graph->checkReachable(promise->get_write(), write)) {
+ if (promise->increment_threads(tid)) {
+ failed_promise = true;
+ return;
+ }
+ }
+ }
+}
+
+/**
+ * Compute the set of writes that may break the current pending release
+ * sequence. This information is extracted from previou release sequence
+ * calculations.
+ *
+ * @param curr The current ModelAction. Must be a release sequence fixup
+ * action.
+ */
+void ModelChecker::compute_relseq_breakwrites(ModelAction *curr)
+{
+ if (pending_rel_seqs->empty())
+ return;
+
+ struct release_seq *pending = pending_rel_seqs->back();
+ for (unsigned int i = 0; i < pending->writes.size(); i++) {
+ const ModelAction *write = pending->writes[i];
+ curr->get_node()->add_relseq_break(write);
+ }
+
+ /* NULL means don't break the sequence; just synchronize */
+ curr->get_node()->add_relseq_break(NULL);
+}
+
/**
* Build up an initial set of all past writes that this 'read' action may read
* from. This set is determined by the clock vector's "happens before"
act->print();
curr->print();
}
- curr->get_node()->add_read_from(act);
+
+ if (curr->get_sleep_flag() && ! curr->is_seqcst()) {
+ if (sleep_can_read_from(curr, act))
+ curr->get_node()->add_read_from(act);
+ } else
+ curr->get_node()->add_read_from(act);
}
/* Include at most one act per-thread that "happens before" curr */
if (!initialized) {
/** @todo Need a more informative way of reporting errors. */
printf("ERROR: may read from uninitialized atomic\n");
+ set_assert();
}
if (DBG_ENABLED() || !initialized) {
curr->get_node()->print_may_read_from();
printf("End printing may_read_from\n");
}
+}
- ASSERT(initialized);
+bool ModelChecker::sleep_can_read_from(ModelAction * curr, const ModelAction *write) {
+ while(true) {
+ Node *prevnode=write->get_node()->get_parent();
+ bool thread_sleep=prevnode->get_enabled_array()[id_to_int(curr->get_tid())]==THREAD_SLEEP_SET;
+ if (write->is_release()&&thread_sleep)
+ return true;
+ if (!write->is_rmw()) {
+ return false;
+ }
+ if (write->get_reads_from()==NULL)
+ return true;
+ write=write->get_reads_from();
+ }
}
static void print_list(action_list_t *list)
printf("---------------------------------------------------------------------\n");
printf("Trace:\n");
-
+ unsigned int hash=0;
+
for (it = list->begin(); it != list->end(); it++) {
(*it)->print();
+ hash=hash^(hash<<3)^((*it)->hash());
}
+ printf("HASH %u\n", hash);
printf("---------------------------------------------------------------------\n");
}
ModelAction *action=*it;
if (action->is_read()) {
fprintf(file, "N%u [label=\"%u, T%u\"];\n", action->get_seq_number(),action->get_seq_number(), action->get_tid());
- fprintf(file, "N%u -> N%u[label=\"rf\", color=red];\n", action->get_seq_number(), action->get_reads_from()->get_seq_number());
+ if (action->get_reads_from()!=NULL)
+ fprintf(file, "N%u -> N%u[label=\"rf\", color=red];\n", action->get_seq_number(), action->get_reads_from()->get_seq_number());
}
if (thread_array[action->get_tid()] != NULL) {
fprintf(file, "N%u -> N%u[label=\"sb\", color=blue];\n", thread_array[action->get_tid()]->get_seq_number(), action->get_seq_number());
scheduler->remove_thread(t);
}
+/**
+ * @brief Get a Thread reference by its ID
+ * @param tid The Thread's ID
+ * @return A Thread reference
+ */
+Thread * ModelChecker::get_thread(thread_id_t tid) const
+{
+ return thread_map->get(id_to_int(tid));
+}
+
+/**
+ * @brief Get a reference to the Thread in which a ModelAction was executed
+ * @param act The ModelAction
+ * @return A Thread reference
+ */
+Thread * ModelChecker::get_thread(ModelAction *act) const
+{
+ return get_thread(act->get_tid());
+}
+
/**
* Switch from a user-context to the "master thread" context (a.k.a. system
* context). This switch is made with the intention of exploring a particular
* model-checking action (described by a ModelAction object). Must be called
* from a user-thread context.
- * @param act The current action that will be explored. Must not be NULL.
+ *
+ * @param act The current action that will be explored. May be NULL only if
+ * trace is exiting via an assertion (see ModelChecker::set_assert and
+ * ModelChecker::has_asserted).
* @return Return status from the 'swap' call (i.e., success/fail, 0/-1)
*/
int ModelChecker::switch_to_master(ModelAction *act)
if (has_asserted())
return false;
- Thread * curr = thread_current();
+ Thread *curr = priv->current_action ? get_thread(priv->current_action) : NULL;
if (curr) {
if (curr->get_state() == THREAD_READY) {
ASSERT(priv->current_action);
ASSERT(false);
}
}
- Thread * next = scheduler->next_thread(priv->nextThread);
+ Thread *next = scheduler->next_thread(priv->nextThread);
/* Infeasible -> don't take any more steps */
if (!isfeasible())
return false;
- if (next)
- next->set_state(THREAD_RUNNING);
- DEBUG("(%d, %d)\n", curr ? curr->get_id() : -1, next ? next->get_id() : -1);
+ if (params.bound != 0) {
+ if (priv->used_sequence_numbers > params.bound) {
+ return false;
+ }
+ }
+
+ DEBUG("(%d, %d)\n", curr ? id_to_int(curr->get_id()) : -1,
+ next ? id_to_int(next->get_id()) : -1);
+
+ /*
+ * Launch end-of-execution release sequence fixups only when there are:
+ *
+ * (1) no more user threads to run (or when execution replay chooses
+ * the 'model_thread')
+ * (2) pending release sequences
+ * (3) pending assertions (i.e., data races)
+ * (4) no pending promises
+ */
+ if (!pending_rel_seqs->empty() && (!next || next->is_model_thread()) &&
+ isfinalfeasible() && !unrealizedraces.empty()) {
+ printf("*** WARNING: release sequence fixup action (%zu pending release seuqences) ***\n",
+ pending_rel_seqs->size());
+ ModelAction *fixup = new ModelAction(MODEL_FIXUP_RELSEQ,
+ std::memory_order_seq_cst, NULL, VALUE_NONE,
+ model_thread);
+ set_current_action(fixup);
+ return true;
+ }
/* next == NULL -> don't take any more steps */
if (!next)
return false;
- if ( next->get_pending() != NULL ) {
- //restart a pending action
+ next->set_state(THREAD_RUNNING);
+
+ if (next->get_pending() != NULL) {
+ /* restart a pending action */
set_current_action(next->get_pending());
next->set_pending(NULL);
next->set_state(THREAD_READY);
projects / model-checker.git / blobdiff