Implement lock IRQ nesting via stack variables/contexts

kernel/sync/rw_spin_lock.c

@@ -2,14 +2,17 @@
 #include <libk/std.h>
 #include <sync/rw_spin_lock.h>
 #include <sys/debug.h>
+#include <sys/irq.h>
 #include <sys/spin_lock.h>
 
 #define WRITER_WAIT (1U << 31)
 #define READER_MASK (~WRITER_WAIT)
 
-void rw_spin_read_lock (rw_spin_lock_t* rw) {
+void rw_spin_read_lock (rw_spin_lock_t* rw, spin_lock_ctx_t* ctx) {
   uint32_t value;
 
+  irq_save (ctx);
+
   for (;;) {
     value = atomic_load_explicit (rw, memory_order_relaxed);
 
@@ -24,14 +27,17 @@ void rw_spin_read_lock (rw_spin_lock_t* rw) {
   }
 }
 
-void rw_spin_read_unlock (rw_spin_lock_t* rw) {
+void rw_spin_read_unlock (rw_spin_lock_t* rw, spin_lock_ctx_t* ctx) {
   uint32_t old = atomic_fetch_sub_explicit (rw, 1, memory_order_release);
   assert ((old & READER_MASK) > 0);
+  irq_restore (ctx);
 }
 
-void rw_spin_write_lock (rw_spin_lock_t* rw) {
+void rw_spin_write_lock (rw_spin_lock_t* rw, spin_lock_ctx_t* ctx) {
   uint32_t value;
 
+  irq_save (ctx);
+
   /* announce writer */
   for (;;) {
     value = atomic_load_explicit (rw, memory_order_relaxed);
@@ -40,8 +46,9 @@ void rw_spin_write_lock (rw_spin_lock_t* rw) {
       if (atomic_compare_exchange_weak_explicit (rw, &value, (value | WRITER_WAIT),
                                                  memory_order_acquire, memory_order_relaxed))
         break;
-    } else
+    } else {
       spin_lock_relax ();
+    }
   }
 
   /* wait for readers */
@@ -54,6 +61,7 @@ void rw_spin_write_lock (rw_spin_lock_t* rw) {
   }
 }
 
-void rw_spin_write_unlock (rw_spin_lock_t* rw) {
+void rw_spin_write_unlock (rw_spin_lock_t* rw, spin_lock_ctx_t* ctx) {
   atomic_store_explicit (rw, 0, memory_order_release);
+  irq_restore (ctx);
 }