Kernel: Fix counting interrupts

Move counting interrupts out of the handle_interrupt method so that
it is done in all cases without the interrupt handler having to
implement it explicitly.

Also make the counter an atomic value as e.g. the LocalAPIC interrupts
may be triggered on multiple processors simultaneously.

Fixes #4297

Kernel/Arch/i386/CPU.cpp

@@ -857,9 +857,11 @@ void handle_interrupt(TrapFrame* trap)
     auto& regs = *trap->regs;
     ASSERT(regs.isr_number >= IRQ_VECTOR_BASE && regs.isr_number <= (IRQ_VECTOR_BASE + GENERIC_INTERRUPT_HANDLERS_COUNT));
     u8 irq = (u8)(regs.isr_number - 0x50);
-    ASSERT(s_interrupt_handler[irq]);
-    s_interrupt_handler[irq]->handle_interrupt(regs);
-    s_interrupt_handler[irq]->eoi();
+    auto* handler = s_interrupt_handler[irq];
+    ASSERT(handler);
+    handler->increment_invoking_counter();
+    handler->handle_interrupt(regs);
+    handler->eoi();
 }
 
 void enter_trap_no_irq(TrapFrame* trap)

Kernel/Interrupts/GenericInterruptHandler.cpp

@@ -62,8 +62,5 @@ void GenericInterruptHandler::change_interrupt_number(u8 number)
     m_interrupt_number = number;
     register_generic_interrupt_handler(InterruptManagement::acquire_mapped_interrupt_number(interrupt_number()), *this);
 }
-void GenericInterruptHandler::increment_invoking_counter()
-{
-    m_invoking_count++;
-}
+
 }

Kernel/Interrupts/GenericInterruptHandler.h

@@ -48,7 +48,7 @@ public:
 
     u8 interrupt_number() const { return m_interrupt_number; }
 
-    size_t get_invoking_count() const { return m_invoking_count; }
+    size_t get_invoking_count() const { return m_invoking_count.load(AK::MemoryOrder::memory_order_relaxed); }
 
     virtual size_t sharing_devices_count() const = 0;
     virtual bool is_shared_handler() const = 0;
@@ -59,7 +59,10 @@ public:
     virtual const char* controller() const = 0;
 
     virtual bool eoi() = 0;
-    void increment_invoking_counter();
+    ALWAYS_INLINE void increment_invoking_counter()
+    {
+        m_invoking_count.fetch_add(1, AK::MemoryOrder::memory_order_relaxed);
+    }
 
 protected:
     void change_interrupt_number(u8 number);
@@ -68,7 +71,7 @@ protected:
     void disable_remap() { m_disable_remap = true; }
 
 private:
-    size_t m_invoking_count { 0 };
+    Atomic<u32> m_invoking_count { 0 };
     u8 m_interrupt_number { 0 };
     bool m_disable_remap { false };
 };

Kernel/Interrupts/SharedIRQHandler.cpp

@@ -87,7 +87,6 @@ SharedIRQHandler::~SharedIRQHandler()
 void SharedIRQHandler::handle_interrupt(const RegisterState& regs)
 {
     ASSERT_INTERRUPTS_DISABLED();
-    increment_invoking_counter();
 #ifdef INTERRUPT_DEBUG
     dbg() << "Interrupt @ " << interrupt_number();
     dbg() << "Interrupt Handlers registered - " << m_handlers.size();