[sampler] Fix data race in Sampler::DoSample

In Sampler::DoSample, we only guard SignalHandler::Installed before
and Sampler::Stop may happen at the same time, which may cause SIGPROF
signal handler was already restored before SIGPROF was emit and trigger
profiling timer expired. This CL changes Sampler::DoSample to use
SignalHandler::mutex() to guard the entire function and also change
the mutex to recursive mutex.

Bug: v8:12838
Change-Id: I5195742ecdbade342986755233840d7be5d83c62
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3616429Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: 王澳 <wangao.james@bytedance.com>
Cr-Commit-Position: refs/heads/main@{#80308}

src/libsampler/sampler.cc

@@ -310,20 +310,23 @@ class Sampler::PlatformData {
 class SignalHandler {
  public:
   static void IncreaseSamplerCount() {
-    base::MutexGuard lock_guard(mutex_.Pointer());
+    base::RecursiveMutexGuard lock_guard(mutex_.Pointer());
     if (++client_count_ == 1) Install();
   }
 
   static void DecreaseSamplerCount() {
-    base::MutexGuard lock_guard(mutex_.Pointer());
+    base::RecursiveMutexGuard lock_guard(mutex_.Pointer());
     if (--client_count_ == 0) Restore();
   }
 
   static bool Installed() {
-    base::MutexGuard lock_guard(mutex_.Pointer());
+    // mutex_ will also be used in Sampler::DoSample to guard the state below.
+    base::RecursiveMutexGuard lock_guard(mutex_.Pointer());
     return signal_handler_installed_;
   }
 
+  static v8::base::RecursiveMutex* mutex() { return mutex_.Pointer(); }
+
  private:
   static void Install() {
     struct sigaction sa;
@@ -349,13 +352,15 @@ class SignalHandler {
   static void HandleProfilerSignal(int signal, siginfo_t* info, void* context);
 
   // Protects the process wide state below.
-  static base::LazyMutex mutex_;
+  static base::LazyRecursiveMutex mutex_;
   static int client_count_;
   static bool signal_handler_installed_;
   static struct sigaction old_signal_handler_;
 };
 
-base::LazyMutex SignalHandler::mutex_ = LAZY_MUTEX_INITIALIZER;
+base::LazyRecursiveMutex SignalHandler::mutex_ =
+    LAZY_RECURSIVE_MUTEX_INITIALIZER;
+
 int SignalHandler::client_count_ = 0;
 struct sigaction SignalHandler::old_signal_handler_;
 bool SignalHandler::signal_handler_installed_ = false;
@@ -568,6 +573,7 @@ void Sampler::Stop() {
 #if defined(USE_SIGNALS)
 
 void Sampler::DoSample() {
+  base::RecursiveMutexGuard lock_guard(SignalHandler::mutex());
   if (!SignalHandler::Installed()) return;
   DCHECK(IsActive());
   SetShouldRecordSample();