From e696ac36d7bab05d749fe567ff53a2ca222b5e69 Mon Sep 17 00:00:00 2001
From: Xu Jun <693788454@qq.com>
Date: Tue, 17 Jan 2023 08:45:29 +0800
Subject: [PATCH] Fix potential block issue in source debugger (#1887)

Fix issue reported in #1860
---
 core/iwasm/interpreter/wasm_interp_classic.c   |  3 ---
 .../libraries/thread-mgr/thread_manager.c      | 18 +++++++++++-------
 .../libraries/thread-mgr/thread_manager.h      |  3 ---
 3 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/core/iwasm/interpreter/wasm_interp_classic.c b/core/iwasm/interpreter/wasm_interp_classic.c
index 46c5ff44..1077910f 100644
--- a/core/iwasm/interpreter/wasm_interp_classic.c
+++ b/core/iwasm/interpreter/wasm_interp_classic.c
@@ -1041,7 +1041,6 @@ wasm_interp_call_func_import(WASMModuleInstance *module_inst,
         }                                                              \
         if (IS_WAMR_STOP_SIG(exec_env->current_status->signal_flag)) { \
             SYNC_ALL_TO_FRAME();                                       \
-            wasm_cluster_thread_stopped(exec_env);                     \
             wasm_cluster_thread_waiting_run(exec_env);                 \
         }                                                              \
     } while (0)
@@ -1077,7 +1076,6 @@ wasm_interp_call_func_import(WASMModuleInstance *module_inst,
                && exec_env->current_status->step_count++ == 1) {          \
             exec_env->current_status->step_count = 0;                     \
             SYNC_ALL_TO_FRAME();                                          \
-            wasm_cluster_thread_stopped(exec_env);                        \
             wasm_cluster_thread_waiting_run(exec_env);                    \
         }                                                                 \
         goto *handle_table[*frame_ip++];                                  \
@@ -1094,7 +1092,6 @@ wasm_interp_call_func_import(WASMModuleInstance *module_inst,
         && exec_env->current_status->step_count++ == 2) {          \
         exec_env->current_status->step_count = 0;                  \
         SYNC_ALL_TO_FRAME();                                       \
-        wasm_cluster_thread_stopped(exec_env);                     \
         wasm_cluster_thread_waiting_run(exec_env);                 \
     }                                                              \
     continue
diff --git a/core/iwasm/libraries/thread-mgr/thread_manager.c b/core/iwasm/libraries/thread-mgr/thread_manager.c
index 4408b013..e307dd61 100644
--- a/core/iwasm/libraries/thread-mgr/thread_manager.c
+++ b/core/iwasm/libraries/thread-mgr/thread_manager.c
@@ -609,17 +609,17 @@ notify_debug_instance_exit(WASMExecEnv *exec_env)
     on_thread_exit_event(cluster->debug_inst, exec_env);
 }
 
-void
-wasm_cluster_thread_stopped(WASMExecEnv *exec_env)
-{
-    exec_env->current_status->running_status = STATUS_STOP;
-    notify_debug_instance(exec_env);
-}
-
 void
 wasm_cluster_thread_waiting_run(WASMExecEnv *exec_env)
 {
     os_mutex_lock(&exec_env->wait_lock);
+
+    /* Wake up debugger thread after we get the lock, otherwise we may miss the
+     * signal from debugger thread, see
+     * https://github.com/bytecodealliance/wasm-micro-runtime/issues/1860 */
+    exec_env->current_status->running_status = STATUS_STOP;
+    notify_debug_instance(exec_env);
+
     while (!wasm_cluster_thread_is_running(exec_env)) {
         os_cond_wait(&exec_env->wait_cond, &exec_env->wait_lock);
     }
@@ -646,16 +646,20 @@ wasm_cluster_thread_exited(WASMExecEnv *exec_env)
 void
 wasm_cluster_thread_continue(WASMExecEnv *exec_env)
 {
+    os_mutex_lock(&exec_env->wait_lock);
     wasm_cluster_clear_thread_signal(exec_env);
     exec_env->current_status->running_status = STATUS_RUNNING;
     os_cond_signal(&exec_env->wait_cond);
+    os_mutex_unlock(&exec_env->wait_lock);
 }
 
 void
 wasm_cluster_thread_step(WASMExecEnv *exec_env)
 {
+    os_mutex_lock(&exec_env->wait_lock);
     exec_env->current_status->running_status = STATUS_STEP;
     os_cond_signal(&exec_env->wait_cond);
+    os_mutex_unlock(&exec_env->wait_lock);
 }
 
 void
diff --git a/core/iwasm/libraries/thread-mgr/thread_manager.h b/core/iwasm/libraries/thread-mgr/thread_manager.h
index c84d3c02..5519960c 100644
--- a/core/iwasm/libraries/thread-mgr/thread_manager.h
+++ b/core/iwasm/libraries/thread-mgr/thread_manager.h
@@ -166,9 +166,6 @@ wasm_cluster_destroy_exenv_status(WASMCurrentEnvStatus *status);
 void
 wasm_cluster_send_signal_all(WASMCluster *cluster, uint32 signo);
 
-void
-wasm_cluster_thread_stopped(WASMExecEnv *exec_env);
-
 void
 wasm_cluster_thread_waiting_run(WASMExecEnv *exec_env);