pushlock: initial implementation

kernel-src/include/mutex.h

@@ -1,25 +1,22 @@
 #ifndef _MUTEX_H
 #define _MUTEX_H
 
-#include <semaphore.h>
+#include <pushlock.h>
 
-typedef semaphore_t mutex_t;
+typedef pushlock_t mutex_t;
 
 #define MUTEX_INIT(m) \
-	SEMAPHORE_INIT(m, 1);
+	*m = 0;
 
 #define MUTEX_ACQUIRE(m) \
-	semaphore_wait(m, false)
-
-#define MUTEX_ACQUIRE_TIMED(m, t) \
-	semaphore_timedwait(m, t, false)
+	pushlock_acquire_exclusive(m)
 
 #define MUTEX_RELEASE(m) \
-	semaphore_signal(m)
+	pushlock_release(m)
 
 #define MUTEX_TRY(m) \
-	semaphore_test(m)
+	pushlock_try_acquire_exclusive(m)
 
-#define MUTEX_DEFINE(x) SEMAPHORE_DEFINE(x, 1)
+#define MUTEX_DEFINE(x) pushlock_t x = 0;
 
 #endif

kernel-src/include/pushlock.h

@@ -0,0 +1,31 @@
+#ifndef _RWLOCK_H
+#define _RWLOCK_H
+
+#include <semaphore.h>
+
+typedef struct pushlock_wait_block_t {
+	struct pushlock_wait_block_t *next;
+	size_t shared_count;
+	semaphore_t semaphore;
+} __attribute__((aligned(8))) pushlock_wait_block_t;
+
+typedef uintptr_t pushlock_t;
+
+#define PUSHLOCK_FLAGS_ACQUIRED 1
+#define PUSHLOCK_FLAGS_EXCLUSIVE 2
+#define PUSHLOCK_FLAGS_CONTENDED 4
+#define PUSHLOCK_MASK_FLAGS 0x7
+#define PUSHLOCK_MASK_POINTER_SHARED_COUNT (0xfffffffffffffff8lu)
+
+#define PUSHLOCK_GET_POINTER(x) ((pushlock_wait_block_t *)((x) & PUSHLOCK_MASK_POINTER_SHARED_COUNT))
+#define PUSHLOCK_GET_SHARED_COUNT(x) ((uintptr_t)PUSHLOCK_GET_POINTER(x) >> 3)
+#define PUSHLOCK_INCREMENT_SHARED_COUNT(x) ((x) + 0x8)
+#define PUSHLOCK_DECREMENT_SHARED_COUNT(x) ((x) - 0x8)
+
+bool pushlock_try_acquire_exclusive(pushlock_t *pushlock);
+void pushlock_acquire_exclusive(pushlock_t *pushlock);
+bool pushlock_try_acquire_shared(pushlock_t *pushlock);
+void pushlock_acquire_shared(pushlock_t *pushlock);
+void pushlock_release(pushlock_t *pushlock);
+
+#endif