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Fix data race when terminating or waiting for a thread (#1924)

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There is a possibility that while iterating through a list of threads, the threads
finish by themselves, making a list of exec_env invalid.
This commit is contained in:
Marcin Kolny 2023-02-06 11:08:45 +00:00 committed by GitHub
parent 2c8375ee67
commit e2c754f0a6
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 74 additions and 18 deletions
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92
core/iwasm/libraries/thread-mgr/thread_manager.c
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@ -76,6 +76,58 @@ traverse_list(bh_list *l, list_visitor visitor, void *user_data)
}
}
/* Assumes cluster->lock is locked */
static bool
safe_traverse_exec_env_list(WASMCluster *cluster, list_visitor visitor,
void *user_data)
{
Vector proc_nodes;
void *node;
bool ret = true;
if (!bh_vector_init(&proc_nodes, cluster->exec_env_list.len, sizeof(void *),
false)) {
ret = false;
goto final;
}
node = bh_list_first_elem(&cluster->exec_env_list);
while (node) {
bool already_processed = false;
void *proc_node;
for (size_t i = 0; i < bh_vector_size(&proc_nodes); i++) {
if (!bh_vector_get(&proc_nodes, i, &proc_node)) {
ret = false;
goto final;
}
if (proc_node == node) {
already_processed = true;
break;
}
}
if (already_processed) {
node = bh_list_elem_next(node);
continue;
}
os_mutex_unlock(&cluster->lock);
visitor(node, user_data);
os_mutex_lock(&cluster->lock);
if (!bh_vector_append(&proc_nodes, &node)) {
ret = false;
goto final;
}
node = bh_list_first_elem(&cluster->exec_env_list);
}
final:
bh_vector_destroy(&proc_nodes);
return ret;
}
/* The caller must lock cluster->lock */
static bool
allocate_aux_stack(WASMCluster *cluster, uint32 *start, uint32 *size)
@ -299,7 +351,6 @@ wasm_cluster_del_exec_env(WASMCluster *cluster, WASMExecEnv *exec_env)
os_mutex_unlock(&cluster->debug_inst->wait_lock);
}
#endif
if (bh_list_remove(&cluster->exec_env_list, exec_env) != 0)
ret = false;
@ -724,16 +775,22 @@ wasm_cluster_join_thread(WASMExecEnv *exec_env, void **ret_val)
korp_tid handle;
os_mutex_lock(&cluster_list_lock);
os_mutex_lock(&exec_env->cluster->lock);
if (!clusters_have_exec_env(exec_env) || exec_env->thread_is_detached) {
/* Invalid thread, thread has exited or thread has been detached */
if (ret_val)
*ret_val = NULL;
os_mutex_unlock(&exec_env->cluster->lock);
os_mutex_unlock(&cluster_list_lock);
return 0;
}
exec_env->wait_count++;
handle = exec_env->handle;
os_mutex_unlock(&exec_env->cluster->lock);
os_mutex_unlock(&cluster_list_lock);
return os_thread_join(handle, ret_val);
}
@ -816,15 +873,22 @@ int32
wasm_cluster_cancel_thread(WASMExecEnv *exec_env)
{
os_mutex_lock(&cluster_list_lock);
os_mutex_lock(&exec_env->cluster->lock);
if (!exec_env->cluster) {
goto final;
}
if (!clusters_have_exec_env(exec_env)) {
/* Invalid thread or the thread has exited */
os_mutex_unlock(&cluster_list_lock);
return 0;
goto final;
}
os_mutex_unlock(&cluster_list_lock);
set_thread_cancel_flags(exec_env);
final:
os_mutex_unlock(&exec_env->cluster->lock);
os_mutex_unlock(&cluster_list_lock);
return 0;
}
@ -846,11 +910,9 @@ wasm_cluster_terminate_all(WASMCluster *cluster)
{
os_mutex_lock(&cluster->lock);
cluster->processing = true;
os_mutex_unlock(&cluster->lock);
traverse_list(&cluster->exec_env_list, terminate_thread_visitor, NULL);
safe_traverse_exec_env_list(cluster, terminate_thread_visitor, NULL);
os_mutex_lock(&cluster->lock);
cluster->processing = false;
os_mutex_unlock(&cluster->lock);
}
@ -861,12 +923,10 @@ wasm_cluster_terminate_all_except_self(WASMCluster *cluster,
{
os_mutex_lock(&cluster->lock);
cluster->processing = true;
os_mutex_unlock(&cluster->lock);
traverse_list(&cluster->exec_env_list, terminate_thread_visitor,
(void *)exec_env);
safe_traverse_exec_env_list(cluster, terminate_thread_visitor,
(void *)exec_env);
os_mutex_lock(&cluster->lock);
cluster->processing = false;
os_mutex_unlock(&cluster->lock);
}
@ -888,11 +948,9 @@ wams_cluster_wait_for_all(WASMCluster *cluster)
{
os_mutex_lock(&cluster->lock);
cluster->processing = true;
os_mutex_unlock(&cluster->lock);
traverse_list(&cluster->exec_env_list, wait_for_thread_visitor, NULL);
safe_traverse_exec_env_list(cluster, wait_for_thread_visitor, NULL);
os_mutex_lock(&cluster->lock);
cluster->processing = false;
os_mutex_unlock(&cluster->lock);
}
@ -903,12 +961,10 @@ wasm_cluster_wait_for_all_except_self(WASMCluster *cluster,
{
os_mutex_lock(&cluster->lock);
cluster->processing = true;
os_mutex_unlock(&cluster->lock);
traverse_list(&cluster->exec_env_list, wait_for_thread_visitor,
(void *)exec_env);
safe_traverse_exec_env_list(cluster, wait_for_thread_visitor,
(void *)exec_env);
os_mutex_lock(&cluster->lock);
cluster->processing = false;
os_mutex_unlock(&cluster->lock);
}