[inspector][fuzzer] Fix termination

Joining the thread from the watchdog is problematic, since e.g.
{pthread_join} (the implementation of {Thread::Join} on POSIX systems)
has undefined behaviour if multiple threads try to join at the same
time. In practice, this leads to deadlocks.

Thus implement termination by just calling {TaskRunner::Terminate}, but
not {TaskRunner::Join}. This fixes the deadlocks in the inspector
fuzzer.
The inspector test binary is fixed simarly, even though there it seems
to not cause problems so far.

In both files, the {Terminate} function is inlined into callers because
it's only a single line now, with one to two users.

Also, replace the single fuzzer test (which is invalid javascript) by
two tests: One called "invalid" explicitly, still with invalid
javascript, and one empty file, which is valid input. That one
reproduced the deadlock.

R=szuend@chromium.org

Bug: chromium:1142437
Change-Id: I8fb98b0cdbf3ceff6af6849397e5da5a4e9acd3c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2526384Reviewed-by: Simon Zünd <szuend@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71054}

test/fuzzer/inspector-fuzzer.cc

@@ -32,13 +32,6 @@ namespace {
 
 base::SmallVector<TaskRunner*, 2> task_runners;
 
-void Terminate() {
-  for (TaskRunner* r : task_runners) {
-    r->Terminate();
-    r->Join();
-  }
-}
-
 class UtilsExtension : public IsolateData::SetupGlobalTask {
  public:
   ~UtilsExtension() override = default;
@@ -88,7 +81,9 @@ class UtilsExtension : public IsolateData::SetupGlobalTask {
   static TaskRunner* backend_runner_;
 
   static void Quit(const v8::FunctionCallbackInfo<v8::Value>& args) {
-    Terminate();
+    // Only terminate, so not join the threads here, since joining concurrently
+    // from multiple threads can be undefined behaviour (see pthread_join).
+    for (TaskRunner* task_runner : task_runners) task_runner->Terminate();
   }
 
   static void CompileAndRunWithOrigin(
@@ -561,7 +556,7 @@ class Watchdog final : public base::Thread {
  private:
   void Run() override {
     if (semaphore_->WaitFor(kMaxExecutionSeconds)) return;
-    Terminate();
+    for (TaskRunner* task_runner : task_runners) task_runner->Terminate();
   }
 
   base::Semaphore* const semaphore_;

test/fuzzer/inspector/foo

-smoke test

test/fuzzer/inspector/invalid

+no valid javascript

test/inspector/inspector-test.cc

@@ -41,13 +41,6 @@ namespace {
 
 base::SmallVector<TaskRunner*, 2> task_runners;
 
-void Terminate() {
-  for (TaskRunner* task_runner : task_runners) {
-    task_runner->Terminate();
-    task_runner->Join();
-  }
-}
-
 class UtilsExtension : public IsolateData::SetupGlobalTask {
  public:
   ~UtilsExtension() override = default;
@@ -154,7 +147,9 @@ class UtilsExtension : public IsolateData::SetupGlobalTask {
   static void Quit(const v8::FunctionCallbackInfo<v8::Value>& args) {
     fflush(stdout);
     fflush(stderr);
-    Terminate();
+    // Only terminate, so not join the threads here, since joining concurrently
+    // from multiple threads can be undefined behaviour (see pthread_join).
+    for (TaskRunner* task_runner : task_runners) task_runner->Terminate();
   }
 
   static void Setlocale(const v8::FunctionCallbackInfo<v8::Value>& args) {