[wasm][debug] Fix DebugInfo deadlock

Add a separate mutex for the {debug_side_tables_} field. This ensures
that we can use {GetDebugSideTableIfExists} even if {mutex_} is already
locked.

R=ahaas@chromium.org
CC=​​clemensb@chromium.org

Bug: v8:10889
Cq-Include-Trybots: luci.v8.try:v8_linux64_tsan_rel_ng
Cq-Include-Trybots: luci.v8.try:v8_linux64_tsan_isolates_rel_ng
Change-Id: Icb67c45aec0cf66814705b83532f4833f36738e1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2402879
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69888}

src/wasm/wasm-debug.cc

@@ -450,8 +450,11 @@ class DebugInfoImpl {
         native_module_->AddCompiledCode(std::move(result)));
 
     DCHECK(new_code->is_inspectable());
+    {
+      base::MutexGuard lock(&debug_side_tables_mutex_);
       DCHECK_EQ(0, debug_side_tables_.count(new_code));
       debug_side_tables_.emplace(new_code, std::move(debug_sidetable));
+    }
 
     return new_code;
   }
@@ -610,14 +613,14 @@ class DebugInfoImpl {
   }
 
   void RemoveDebugSideTables(Vector<WasmCode* const> codes) {
-    base::MutexGuard guard(&mutex_);
+    base::MutexGuard guard(&debug_side_tables_mutex_);
     for (auto* code : codes) {
       debug_side_tables_.erase(code);
     }
   }
 
   DebugSideTable* GetDebugSideTableIfExists(const WasmCode* code) const {
-    base::MutexGuard guard(&mutex_);
+    base::MutexGuard guard(&debug_side_tables_mutex_);
     auto it = debug_side_tables_.find(code);
     return it == debug_side_tables_.end() ? nullptr : it->second.get();
   }
@@ -687,7 +690,7 @@ class DebugInfoImpl {
     {
       // Only hold the mutex temporarily. We can't hold it while generating the
       // debug side table, because compilation takes the {NativeModule} lock.
-      base::MutexGuard guard(&mutex_);
+      base::MutexGuard guard(&debug_side_tables_mutex_);
       auto it = debug_side_tables_.find(code);
       if (it != debug_side_tables_.end()) return it->second.get();
     }
@@ -708,7 +711,7 @@ class DebugInfoImpl {
     // Check cache again, maybe another thread concurrently generated a debug
     // side table already.
     {
-      base::MutexGuard guard(&mutex_);
+      base::MutexGuard guard(&debug_side_tables_mutex_);
       auto& slot = debug_side_tables_[code];
       if (slot != nullptr) return slot.get();
       slot = std::move(debug_side_table);
@@ -847,13 +850,15 @@ class DebugInfoImpl {
 
   NativeModule* const native_module_;
 
-  // {mutex_} protects all fields below.
-  mutable base::Mutex mutex_;
+  mutable base::Mutex debug_side_tables_mutex_;
 
   // DebugSideTable per code object, lazily initialized.
   std::unordered_map<const WasmCode*, std::unique_ptr<DebugSideTable>>
       debug_side_tables_;
 
+  // {mutex_} protects all fields below.
+  mutable base::Mutex mutex_;
+
   // Names of locals, lazily decoded from the wire bytes.
   std::unique_ptr<LocalNames> local_names_;
 

test/cctest/wasm/test-wasm-breakpoints.cc

@@ -574,6 +574,13 @@ WASM_COMPILED_EXEC_TEST(WasmBreakInPostMVP) {
   CHECK_EQ(kReturn, GetIntReturnValue(retval));
 }
 
+WASM_COMPILED_EXEC_TEST(Regress10889) {
+  FLAG_SCOPE(print_wasm_code);
+  WasmRunner<int> runner(execution_tier);
+  BUILD(runner, WASM_I32V_1(0));
+  SetBreakpoint(&runner, runner.function_index(), 1, 1);
+}
+
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8