commit 07e3ca9a46801990d662c48d0fddedc63c4c053c
author Nicolas Geoffray <ngeoffray@google.com> Fri Mar 11 09:57:57 2016 +0000
committer Nicolas Geoffray <ngeoffray@google.com> Fri Mar 11 09:57:57 2016 +0000
tree 94fedc96b28c6a46d2b83c80b2cfefd4c2898f4a
parent b7f257f353b1eb2db2732939a0404c118316891d

Fix thread race when fetching the ProfilingInfo object.

Problem is:
1) Compiler fetches the ProfilingInfo of A, it's null.
2) Mutator creates the ProfilingInfo.
3) Compiler notifies it's not using A anymore, calls
   ProfilingInfo::DecrementInlineUse -> Crash as we expected
   ProfilingInfo::IncrementUse to be called before.

Also update some namings to better reflect what is going on.

Change-Id: I55ea4c5d81988131467095e18a0d13a8be9d0ef7

runtime/jit/jit_code_cache.cc

diff --git a/runtime/jit/jit_code_cache.cc b/runtime/jit/jit_code_cache.cc
index 050bb68..af47da6 100644
--- a/runtime/jit/jit_code_cache.cc
+++ b/runtime/jit/jit_code_cache.cc
@@ -928,20 +928,20 @@
   return true;
 }
 
-void JitCodeCache::NotifyInliningOf(ArtMethod* method, Thread* self) {
+ProfilingInfo* JitCodeCache::NotifyCompilerUse(ArtMethod* method, Thread* self) {
   MutexLock mu(self, lock_);
   ProfilingInfo* info = method->GetProfilingInfo(sizeof(void*));
   if (info != nullptr) {
     info->IncrementInlineUse();
   }
+  return info;
 }
 
-void JitCodeCache::DoneInlining(ArtMethod* method, Thread* self) {
+void JitCodeCache::DoneCompilerUse(ArtMethod* method, Thread* self) {
   MutexLock mu(self, lock_);
   ProfilingInfo* info = method->GetProfilingInfo(sizeof(void*));
-  if (info != nullptr) {
-    info->DecrementInlineUse();
-  }
+  DCHECK(info != nullptr);
+  info->DecrementInlineUse();
 }
 
 void JitCodeCache::DoneCompiling(ArtMethod* method, Thread* self ATTRIBUTE_UNUSED) {

runtime/jit/jit_code_cache.h

diff --git a/runtime/jit/jit_code_cache.h b/runtime/jit/jit_code_cache.h
index 113bebf..98dd70d 100644
--- a/runtime/jit/jit_code_cache.h
+++ b/runtime/jit/jit_code_cache.h
@@ -71,7 +71,11 @@
       SHARED_REQUIRES(Locks::mutator_lock_)
       REQUIRES(!lock_);
 
-  void NotifyInliningOf(ArtMethod* method, Thread* self)
+  // Notify to the code cache that the compiler wants to use the
+  // profiling info of `method` to drive optimizations,
+  // and therefore ensure the returned profiling info object is not
+  // collected.
+  ProfilingInfo* NotifyCompilerUse(ArtMethod* method, Thread* self)
       SHARED_REQUIRES(Locks::mutator_lock_)
       REQUIRES(!lock_);
 
@@ -79,7 +83,7 @@
       SHARED_REQUIRES(Locks::mutator_lock_)
       REQUIRES(!lock_);
 
-  void DoneInlining(ArtMethod* method, Thread* self)
+  void DoneCompilerUse(ArtMethod* method, Thread* self)
       SHARED_REQUIRES(Locks::mutator_lock_)
       REQUIRES(!lock_);
 

runtime/jit/profiling_info.h

diff --git a/runtime/jit/profiling_info.h b/runtime/jit/profiling_info.h
index 73c1a1e..55d627a 100644
--- a/runtime/jit/profiling_info.h
+++ b/runtime/jit/profiling_info.h
@@ -56,10 +56,11 @@
   mirror::Class* GetMonomorphicType() const SHARED_REQUIRES(Locks::mutator_lock_) {
     // Note that we cannot ensure the inline cache is actually monomorphic
     // at this point, as other threads may have updated it.
+    DCHECK(!classes_[0].IsNull());
     return classes_[0].Read();
   }
 
-  bool IsUnitialized() const {
+  bool IsUninitialized() const {
     return classes_[0].IsNull();
   }