Add J9HookInterface.J9HookUnreserve() to clear flag J9HOOK_FLAG_RESERVED

J9HookRegister() sets flags J9HOOK_FLAG_HOOKED | J9HOOK_FLAG_RESERVED, J9HookUnregister() only clears J9HOOK_FLAG_HOOKED, add J9HookUnreserve() to clear J9HOOK_FLAG_RESERVED. This supports an event to be registered, unregistered/unreserved, and disabled. Otherwise, an unregistered event can't be disabled by J9HookDisable() because of the presence of J9HOOK_FLAG_RESERVED. Signed-off-by: Jason Feng <[email protected]>
rmnattas · Jul 23, 2024 · 8159d04 · 8159d04
1 parent 56cb81f
commit 8159d04
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diff --git a/include_core/omrhookable.h b/include_core/omrhookable.h
@@ -53,6 +53,7 @@ typedef struct J9HookInterface {
 	void (*J9HookDispatch)(struct J9HookInterface **hookInterface, uintptr_t eventNum, void *eventData);
 	intptr_t (*J9HookDisable)(struct J9HookInterface **hookInterface, uintptr_t eventNum);
 	intptr_t (*J9HookReserve)(struct J9HookInterface **hookInterface, uintptr_t eventNum);
+	void (*J9HookUnreserve)(struct J9HookInterface **hookInterface, uintptr_t eventNum);
 	intptr_t (*J9HookRegister)(struct J9HookInterface **hookInterface, uintptr_t eventNum, J9HookFunction function, void *userData, ...);
 	intptr_t (*J9HookRegisterWithCallSite)(struct J9HookInterface **hookInterface, uintptr_t eventNum, J9HookFunction function, const char *callsite, void *userData, ...);
 	void (*J9HookUnregister)(struct J9HookInterface **hookInterface, uintptr_t eventNum, J9HookFunction function, void *userData);

diff --git a/util/hookable/hookable.cpp b/util/hookable/hookable.cpp
@@ -41,13 +41,15 @@ static intptr_t J9HookDisable(struct J9HookInterface **hookInterface, uintptr_t
 static intptr_t J9HookIsEnabled(struct J9HookInterface **hookInterface, uintptr_t taggedEventNum);
 static void J9HookDispatch(struct J9HookInterface **hookInterface, uintptr_t taggedEventNum, void *eventData);
 static intptr_t J9HookReserve(struct J9HookInterface **hookInterface, uintptr_t taggedEventNum);
+static void J9HookUnreserve(struct J9HookInterface **hookInterface, uintptr_t taggedEventNum);
 static uintptr_t J9HookAllocateAgentID(struct J9HookInterface **hookInterface);
 static void J9HookDeallocateAgentID(struct J9HookInterface **hookInterface, uintptr_t agentID);
 
 static const J9HookInterface hookFunctionTable = {
 	J9HookDispatch,
 	J9HookDisable,
 	J9HookReserve,
+	J9HookUnreserve,
 	J9HookRegister,
 	J9HookRegisterWithCallSite,
 	J9HookUnregister,
@@ -345,6 +347,26 @@ J9HookReserve(struct J9HookInterface **hookInterface, uintptr_t taggedEventNum)
 	return rc;
 }
 
+/*
+ * Clear the J9HOOK_FLAG_RESERVED flag from an event.
+ * This flag can be removed regardless of current flag(s) of the event,
+ * J9HOOK_FLAG_RESERVED, J9HOOK_FLAG_HOOKED or J9HOOK_FLAG_DISABLED.
+ *
+ * This function should not be called directly. It should be called through the hook interface.
+ */
+static void
+J9HookUnreserve(struct J9HookInterface **hookInterface, uintptr_t taggedEventNum)
+{
+	J9CommonHookInterface *commonInterface = (J9CommonHookInterface *)hookInterface;
+	uintptr_t eventNum = taggedEventNum & J9HOOK_EVENT_NUM_MASK;
+
+	omrthread_monitor_enter(commonInterface->lock);
+
+	HOOK_FLAGS(commonInterface, eventNum) &= ~J9HOOK_FLAG_RESERVED;
+
+	omrthread_monitor_exit(commonInterface->lock);
+}
+
 static intptr_t
 J9HookRegisterWithCallSitePrivate(struct J9HookInterface **hookInterface, uintptr_t taggedEventNum, J9HookFunction function, const char *callsite, void *userData, uintptr_t agentID)
 {