On Thu, 11 Apr 2024 22:54:16 GMT, Serguei Spitsyn <[email protected]> wrote:
>> src/hotspot/share/prims/jvmtiEnvThreadState.cpp line 367:
>>
>>> 365: GetCurrentLocationClosure op;
>>> 366: JvmtiHandshake::execute(&op, &tlh, thread, thread_h);
>>> 367:
>>
>> Seems we are missing a JvmtiVTMSTransitionDisabler.
>
> Good question, thanks.
> The `JvmtiVTMSTransitionDisabler` is supposed to be installed in the caller's
> context if needed.
> However, it is not easy to make sure it is always the case.
> At least, I see a couple of contexts when the `JvmtiVTMSTransitionDisabler`
> is not being installed.
> But it is not clear if it is really needed there. Let me do some extra
> analysis there.
Okay. The class `GetCurrentLocationClosure` is used by the
`reset_current_location` only. It is called for the SINGLE_STEP and REAKPOINT
event types as the following assert is placed at the function start:
void JvmtiEnvThreadState::reset_current_location(jvmtiEvent event_type, bool
enabled) {
assert(event_type == JVMTI_EVENT_SINGLE_STEP || event_type ==
JVMTI_EVENT_BREAKPOINT,
"must be single-step or breakpoint event");
. . .
Also, this is the only two places where this function is called:
JvmtiEventControllerPrivate::recompute_env_thread_enabled(JvmtiEnvThreadState*
ets, JvmtiThreadState* state) {
. . .
if (changed & SINGLE_STEP_BIT) {
ets->reset_current_location(JVMTI_EVENT_SINGLE_STEP, (now_enabled &
SINGLE_STEP_BIT) != 0);
}
if (changed & BREAKPOINT_BIT) {
ets->reset_current_location(JVMTI_EVENT_BREAKPOINT, (now_enabled &
BREAKPOINT_BIT) != 0);
}
The `reset_current_location` is called called in the context of the
`SetEventNotificationMode` where a JvmtiVTMSTransitionDisabler is present.
Theoretically, it can be also triggered by the `SetEventCallbacks` (if
callbacks are for SINGLE_STEP or REAKPOINT event type). But it also has a
J`vmtiVTMSTransitionDisabler` in place:
JvmtiEnv::SetEventCallbacks(const jvmtiEventCallbacks* callbacks, jint
size_of_callbacks) {
JvmtiVTMSTransitionDisabler disabler;
JvmtiEventController::set_event_callbacks(this, callbacks, size_of_callbacks);
return JVMTI_ERROR_NONE;
} /* end SetEventCallbacks */
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PR Review Comment: https://git.openjdk.org/jdk/pull/18630#discussion_r1561903953
