From 79745507a93c8788e4c8ee863368b95b7e993517 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Wed, 21 Jul 2021 20:21:29 +0200
Subject: [PATCH] Kernel: Use IntrusiveList for keeping track of
 GenericInterruptHandlers

---
 Kernel/Interrupts/GenericInterruptHandler.h |  8 ++++++--
 Kernel/Interrupts/SharedIRQHandler.cpp      | 18 ++++++++----------
 Kernel/Interrupts/SharedIRQHandler.h        |  5 ++---
 3 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/Kernel/Interrupts/GenericInterruptHandler.h b/Kernel/Interrupts/GenericInterruptHandler.h
index 3f68ae8ee5..b4a96ec385 100644
--- a/Kernel/Interrupts/GenericInterruptHandler.h
+++ b/Kernel/Interrupts/GenericInterruptHandler.h
@@ -6,8 +6,7 @@
 
 #pragma once
 
-#include <AK/HashTable.h>
-#include <AK/String.h>
+#include <AK/IntrusiveList.h>
 #include <AK/Types.h>
 #include <Kernel/Arch/x86/RegisterState.h>
 
@@ -65,5 +64,10 @@ private:
     u8 m_interrupt_number { 0 };
     bool m_disable_remap { false };
     bool m_registered { false };
+
+    IntrusiveListNode<GenericInterruptHandler> m_list_node;
+
+public:
+    using List = IntrusiveList<GenericInterruptHandler, RawPtr<GenericInterruptHandler>, &GenericInterruptHandler::m_list_node>;
 };
 }
diff --git a/Kernel/Interrupts/SharedIRQHandler.cpp b/Kernel/Interrupts/SharedIRQHandler.cpp
index 25d065e2de..b35bba7ec6 100644
--- a/Kernel/Interrupts/SharedIRQHandler.cpp
+++ b/Kernel/Interrupts/SharedIRQHandler.cpp
@@ -24,13 +24,13 @@ UNMAP_AFTER_INIT void SharedIRQHandler::initialize(u8 interrupt_number)
 void SharedIRQHandler::register_handler(GenericInterruptHandler& handler)
 {
     dbgln_if(INTERRUPT_DEBUG, "Interrupt Handler registered @ Shared Interrupt Handler {}", interrupt_number());
-    m_handlers.set(&handler);
+    m_handlers.append(handler);
     enable_interrupt_vector();
 }
 void SharedIRQHandler::unregister_handler(GenericInterruptHandler& handler)
 {
     dbgln_if(INTERRUPT_DEBUG, "Interrupt Handler unregistered @ Shared Interrupt Handler {}", interrupt_number());
-    m_handlers.remove(&handler);
+    m_handlers.remove(handler);
     if (m_handlers.is_empty())
         disable_interrupt_vector();
 }
@@ -44,9 +44,8 @@ bool SharedIRQHandler::eoi()
 
 void SharedIRQHandler::enumerate_handlers(Function<void(GenericInterruptHandler&)>& callback)
 {
-    for (auto* handler : m_handlers) {
-        VERIFY(handler);
-        callback(*handler);
+    for (auto& handler : m_handlers) {
+        callback(handler);
     }
 }
 
@@ -69,15 +68,14 @@ bool SharedIRQHandler::handle_interrupt(const RegisterState& regs)
 
     if constexpr (INTERRUPT_DEBUG) {
         dbgln("Interrupt @ {}", interrupt_number());
-        dbgln("Interrupt Handlers registered - {}", m_handlers.size());
+        dbgln("Interrupt Handlers registered - {}", m_handlers.size_slow());
     }
     int i = 0;
     bool was_handled = false;
-    for (auto* handler : m_handlers) {
+    for (auto& handler : m_handlers) {
         dbgln_if(INTERRUPT_DEBUG, "Going for Interrupt Handling @ {}, Shared Interrupt {}", i, interrupt_number());
-        VERIFY(handler != nullptr);
-        if (handler->handle_interrupt(regs)) {
-            handler->increment_invoking_counter();
+        if (handler.handle_interrupt(regs)) {
+            handler.increment_invoking_counter();
             was_handled = true;
         }
         dbgln_if(INTERRUPT_DEBUG, "Going for Interrupt Handling @ {}, Shared Interrupt {} - End", i, interrupt_number());
diff --git a/Kernel/Interrupts/SharedIRQHandler.h b/Kernel/Interrupts/SharedIRQHandler.h
index de7e363fcb..389d7b6659 100644
--- a/Kernel/Interrupts/SharedIRQHandler.h
+++ b/Kernel/Interrupts/SharedIRQHandler.h
@@ -6,7 +6,6 @@
 
 #pragma once
 
-#include <AK/HashTable.h>
 #include <AK/NonnullOwnPtr.h>
 #include <AK/RefPtr.h>
 #include <AK/Types.h>
@@ -28,7 +27,7 @@ public:
 
     void enumerate_handlers(Function<void(GenericInterruptHandler&)>&);
 
-    virtual size_t sharing_devices_count() const override { return m_handlers.size(); }
+    virtual size_t sharing_devices_count() const override { return m_handlers.size_slow(); }
     virtual bool is_shared_handler() const override { return true; }
     virtual bool is_sharing_with_others() const override { return false; }
 
@@ -41,7 +40,7 @@ private:
     void disable_interrupt_vector();
     explicit SharedIRQHandler(u8 interrupt_number);
     bool m_enabled { true };
-    HashTable<GenericInterruptHandler*> m_handlers;
+    GenericInterruptHandler::List m_handlers;
     RefPtr<IRQController> m_responsible_irq_controller;
 };
 }