hrtimer expires
                   │
                   ▼
  ========================================
            HARDIRQ (Top Half)
  ========================================
             Timer Callback
         (cannot sleep, fast)
                   │
                   ▼
 queue_work(event_wq, &work)
                   │
                   ▼
  ========================================
        WORKQUEUE (Bottom Half)
  ========================================
   runs in kworker → sleeps allowed
writes event to buffer, prints log

---

┌──────────────────────────────────────────────────────────────┐ │ Kernel Module │ └──────────────────────────────────────────────────────────────┘

     ┌────────────────────────────────────────────────┐
     │               HRTIMER SOURCES                  │
     │ (Simulated Interrupt Generators — 100ms each)  │
     └────────────────────────────────────────────────┘
               │               │                │
               ▼               ▼                ▼

    ┌────────────────┐ ┌────────────────┐ ┌────────────────┐
    │ NETWORK Timer  │ │ KEYBOARD Timer │ │  SENSOR Timer  │
    └────────────────┘ └────────────────┘ └────────────────┘
               │               │                │
               │ Timer fires   │ Timer fires    │ Timer fires
               ▼               ▼                ▼

======================================================================= (Simulated INTERRUPT CONTEXT — FAST)

                  TIMER CALLBACK (ISR)

---

• Identify which timer fired
• Allocate event_work
• INIT_WORK()
• queue_work(event_wq, &work)
• hrtimer_forward_now()

               │
               ▼

======================================================================= (Deferred work — BOTTOM HALF)

          WORKQUEUE: event_wq (kworker threads)
          --------------------------------------
          Many events may run in parallel here.
          --------------------------------------

               ▼

    ┌───────────────────────────────────────────────┐
    │            process_event(work_struct)         │
    └───────────────────────────────────────────────┘
    • Acquire spinlock  
    • Write into circular event_buffer  
    • buffer_head = (buffer_head + 1) % N  
    • Release spinlock  
    • printk("Event processed")  

               ▼

┌───────────────────────────────────────────────────────────────┐ │ Circular Event Buffer (Protected) │ │───────────────────────────────────────────────────────────────│ │ [0] timestamp, type, "Event from source X" │ │ [1] timestamp, type, "Event from source X" │ │ .... up to EVENT_BUFFER_SIZE │ └───────────────────────────────────────────────────────────────┘

               ▼

======================================================================= USER-SPACE INTERFACE (Procfs)

                 /proc/fake_events

When user runs: $ cat /proc/fake_events

Kernel executes: proc_show() • Acquire spinlock • Print all valid events in seq_file format • Release spinlock • Return output to user

=======================================================================