1 files changed, 39 insertions, 0 deletions
diff --git a/spinlock.c b/spinlock.c
new file mode 100644
index 0000000..fa04a27
--- /dev/null
+++ b/spinlock.c
@@ -0,0 +1,39 @@
+#include "types.h"
+#include "defs.h"
+#include "x86.h"
+
+#define LOCK_FREE -1
+
+uint32_t kernel_lock = LOCK_FREE;
+
+// lock = LOCK_FREE if free, else = cpu_id of owner CPU
+void 
+acquire_spinlock(uint32_t* lock)
+{
+  int cpu_id = lapic_cpu_number();
+  cprintf ("acquire: %d\n", cpu_id);
+
+  if (*lock == cpu_id)
+    return;
+  while ( cmpxchg(LOCK_FREE, cpu_id, lock) != cpu_id ) { ; }
+}
+
+void
+release_spinlock(uint32_t* lock)
+{
+  int cpu_id = lapic_cpu_number();
+  cprintf ("release: %d\n", cpu_id);
+  if (*lock != cpu_id)
+    panic("release_spinlock: releasing a lock that i don't own\n");
+  *lock = LOCK_FREE;
+}
+
+void
+release_grant_spinlock(uint32_t* lock, int c)
+{
+  int cpu_id = lapic_cpu_number();
+  cprintf ("release_grant: %d -> %d\n", cpu_id, c);
+  if (*lock != cpu_id)
+    panic("release_spinlock: releasing a lock that i don't own\n");
+  *lock = c;
+}