From 7759eef8cdac79028dd5b468bd9ce0cf1c12b162 Mon Sep 17 00:00:00 2001
From: Richard Qin <richard.qin.x@gmail.com>
Date: Tue, 30 Dec 2025 14:21:40 +0800
Subject: dev(spinlock): refactoring the implementation of locks

---
 include/kernel/proc.h     | 22 ++++++++++++++++---
 include/kernel/spinlock.h | 54 ++++++++++++++++++++++++++++++++++++-----------
 2 files changed, 61 insertions(+), 15 deletions(-)

(limited to 'include')

diff --git a/include/kernel/proc.h b/include/kernel/proc.h
index b557267..e77fdc9 100644
--- a/include/kernel/proc.h
+++ b/include/kernel/proc.h
@@ -3,11 +3,13 @@
 #include "kernel/trap.h"
 #include "kernel/spinlock.h"
 
+// Context structure, used for context switching
 struct Context
 {
     uint64 ra;
     uint64 sp;
 
+    // Callee-saved registers
     uint64 s0;
     uint64 s1;
     uint64 s2;
@@ -22,7 +24,9 @@ struct Context
     uint64 s11;
 };
 
-enum ProcState{
+// Process State Enumeration
+enum ProcState
+{
     UNUSED,
     USED,
     SLEEPING,
@@ -31,6 +35,7 @@ enum ProcState{
     ZOMBIE,
 };
 
+// Process Control Block (PCB)
 struct Proc
 {
     struct Context context;
@@ -41,15 +46,25 @@ struct Proc
     enum ProcState state;
     int pid;
 
-    void* kstack;
+    void *kstack;
     char name[16];
     uint64 sz;
 
     struct Proc *parent;
     void *chan;
     int xstate;
+
+    // Implement later
 };
 
+// CPU status structure
+struct cpu
+{
+    struct Proc *proc;      // Processes currently running on this CPU
+    struct Context context; // Save the scheduler context here
+    int noff;               // Depth of push_off()
+    int intena;             // Interrupt enable status before closing
+};
 
 namespace ProcManager
 {
@@ -62,7 +77,8 @@ namespace ProcManager
     void user_init();
     void exit(int status);
     int wait(uint64 addr);
-    void sleep(void *chan, struct spinlock *lk);
+
+    void sleep(void *chan, Spinlock *lk);
     void wakeup(void *chan);
 }
 
diff --git a/include/kernel/spinlock.h b/include/kernel/spinlock.h
index aec4b6a..b3cc93e 100644
--- a/include/kernel/spinlock.h
+++ b/include/kernel/spinlock.h
@@ -1,20 +1,50 @@
 #pragma once
+
 #include "common/types.h"
 
-struct spinlock
+struct cpu;
+struct Proc;
+
+// Spinlock
+// Features: Non-interruptible, busy-wait loop, extremely short hold time.
+// Scenario: Protecting core data such as scheduler, interrupt handling, PMM, etc.
+class Spinlock
 {
-    uint locked;
+public:
+    volatile uint32 locked;     // Whether it is locked (0: unlocked, 1: locked)
+    const char *name;      // Lock Name (for debugging)
+    struct cpu *cpu; // The CPU holding the lock
+
+    // Constructor
+    Spinlock() : locked(0), name("uninit"), cpu(nullptr) {}
+
+    // Initialize lock name
+    void init(const char *name);
 
-    char *name;
-    int cpu_id;
+    // Acquire lock
+    void acquire();
+
+    // Release lock
+    void release();
+
+    // Check if the current CPU holds the lock
+    bool holding();
 };
 
-namespace Spinlock
+// Mutex
+// Features: Allows interruption, allows sleeping (yield CPU), can hold for a long time.
+// Scenarios: File system IO, device driver waiting, long-term buffering operations.
+class Mutex
 {
-    void init(struct spinlock *lk, char *name);
-    void acquire(struct spinlock *lk);
-    void release(struct spinlock *lk);
-    int holding(struct spinlock *lk);
-    void push_off();
-    void pop_off();
-}
\ No newline at end of file
+public:
+    uint32 locked;    // Whether it is locked
+    const char *name; // Lock Name
+    int pid;          // PID of the process holding the lock (for debugging)
+
+    Spinlock lk; // Internal spin lock, protects the state of the Mutex itself
+
+    void init(const char *name);
+    void acquire();
+    void release();
+    bool holding();
+};
\ No newline at end of file
-- 
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