From a02c1fcebd4d8d33f8a16e43833fe34c951fa982 Mon Sep 17 00:00:00 2001
From: Imbus <>
Date: Tue, 2 Sep 2025 04:43:55 +0200
Subject: [PATCH] Use compiler builtins for spin_unlock, correct initialization
 for spinlock_init

---
 kern/libkern/spinlock.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/kern/libkern/spinlock.c b/kern/libkern/spinlock.c
index b9ccd8b..7fdf294 100644
--- a/kern/libkern/spinlock.c
+++ b/kern/libkern/spinlock.c
@@ -3,6 +3,7 @@
  * (Not mutexes as these are spinning locks).
  */
 
+#include "stddef.h"
 #include <panic.h>
 #include <proc.h>
 #include <riscv.h>
@@ -79,6 +80,7 @@ uint32_t pop_off(void) {
 
 void spinlock_init(spinlock_t *l) {
     l->v = 0;
+    l->cpu = NULL;
 }
 
 __attribute__((warn_unused_result)) bool spin_trylock(spinlock_t *l) {
@@ -92,15 +94,11 @@ void spin_unlock(spinlock_t *l) {
     if (!spin_is_holding(l))
         PANIC("Unlocking a spinlock that is not held by the locking cpu!");
 
-    l->cpu = 0;
-
-    // Release: store 0 with .rl ordering.
-    uint32_t dummy;
-    __asm__ volatile("amoswap.w.rl %0, %2, (%1)\n" : "=&r"(dummy) : "r"(&l->v), "r"(0u) : "memory");
-
-    __sync_synchronize(); // No loads/stores after this point
-    // __sync_lock_release(&lk->locked); // Essentially lk->locked = 0
+    /* TODO: Replace with corresponding __atomic builtins */
+    __sync_lock_release(&l->v);
+    __sync_synchronize();
 
+    l->cpu = NULL;
     pop_off();
 }