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src/hotspot/share/oops/method.cpp

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rev 56251 : imported patch 8226705-v1
rev 56252 : imported patch 8226705-v2

@@ -101,11 +101,11 @@
   set_vtable_index(Method::garbage_vtable_index);
 
   // Fix and bury in Method*
   set_interpreter_entry(NULL); // sets i2i entry and from_int
   set_adapter_entry(NULL);
-  clear_code(false /* don't need a lock */); // from_c/from_i get set to c2i/i2i
+  Method::clear_code(); // from_c/from_i get set to c2i/i2i
 
   if (access_flags.is_native()) {
     clear_native_function();
     set_signature_handler(NULL);
   }

@@ -823,11 +823,11 @@
 void Method::clear_native_function() {
   // Note: is_method_handle_intrinsic() is allowed here.
   set_native_function(
     SharedRuntime::native_method_throw_unsatisfied_link_error_entry(),
     !native_bind_event_is_interesting);
-  clear_code();
+  this->unlink_code();
 }
 
 
 void Method::set_signature_handler(address handler) {
   address* signature_handler =  signature_handler_addr();

@@ -939,12 +939,11 @@
   CompilationPolicy::policy()->disable_compilation(this);
   assert(!CompilationPolicy::can_be_osr_compiled(this, comp_level), "sanity check");
 }
 
 // Revert to using the interpreter and clear out the nmethod
-void Method::clear_code(bool acquire_lock /* = true */) {
-  MutexLocker pl(acquire_lock ? Patching_lock : NULL, Mutex::_no_safepoint_check_flag);
+void Method::clear_code() {
   // this may be NULL if c2i adapters have not been made yet
   // Only should happen at allocate time.
   if (adapter() == NULL) {
     _from_compiled_entry    = NULL;
   } else {

@@ -954,10 +953,29 @@
   _from_interpreted_entry = _i2i_entry;
   OrderAccess::storestore();
   _code = NULL;
 }
 
+void Method::unlink_code(CompiledMethod *compare) {
+  MutexLocker ml(CompiledMethod_lock->owned_by_self() ? NULL : CompiledMethod_lock, Mutex::_no_safepoint_check_flag);
+  // We need to check if either the _code or _from_compiled_code_entry_point
+  // refer to this nmethod because there is a race in setting these two fields
+  // in Method* as seen in bugid 4947125.
+  // If the vep() points to the zombie nmethod, the memory for the nmethod
+  // could be flushed and the compiler and vtable stubs could still call
+  // through it.
+  if (code() == compare ||
+      from_compiled_entry() == compare->verified_entry_point()) {
+    clear_code();
+  }
+}
+
+void Method::unlink_code() {
+  MutexLocker ml(CompiledMethod_lock->owned_by_self() ? NULL : CompiledMethod_lock, Mutex::_no_safepoint_check_flag);
+  clear_code();
+}
+
 #if INCLUDE_CDS
 // Called by class data sharing to remove any entry points (which are not shared)
 void Method::unlink_method() {
   _code = NULL;
 

@@ -1180,11 +1198,11 @@
   return code == NULL || (code->method() == NULL) || (code->method() == (Method*)this && !code->is_osr_method());
 }
 
 // Install compiled code.  Instantly it can execute.
 void Method::set_code(const methodHandle& mh, CompiledMethod *code) {
-  MutexLocker pl(Patching_lock, Mutex::_no_safepoint_check_flag);
+  assert_lock_strong(CompiledMethod_lock);
   assert( code, "use clear_code to remove code" );
   assert( mh->check_code(), "" );
 
   guarantee(mh->adapter() != NULL, "Adapter blob must already exist!");
 
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