Implement proper mutex cleanup

init/init.c

@@ -6,7 +6,7 @@
 #include <stdint.h>
 #include <string/string.h>
 
-#define EXAMPLE 2
+#define EXAMPLE 3
 
 #if EXAMPLE == 1
 
@@ -57,6 +57,49 @@ void app_main (void) {
   }
 }
 
+void app_thread1 (void) {
+  for (;;) {
+    lock_mutex (MUTEX, RV_PRIVATE);
+
+    for (int i = 0; i < 3; i++)
+      test ('b');
+
+    unlock_mutex (MUTEX, RV_PRIVATE);
+  }
+
+  quit ();
+}
+#elif EXAMPLE == 3
+
+#define MUTEX 2000
+
+void app_thread1 (void);
+
+int spawn (void (*fn) (void)) {
+  size_t stack_size = 256 * PAGE_SIZE;
+  void* stack = malloc (stack_size);
+  if (stack == NULL)
+    return -ST_OOM_ERROR;
+
+  uintptr_t stack_top = (uintptr_t)stack + stack_size;
+  return clone (stack_top, stack_size, fn);
+}
+
+void app_main (void) {
+  create_mutex (MUTEX, RV_PRIVATE);
+
+  spawn (&app_thread1);
+
+  for (;;) {
+    lock_mutex (MUTEX, RV_PRIVATE);
+
+    for (int i = 0; i < 3; i++)
+      test ('a');
+
+    quit ();
+  }
+}
+
 void app_thread1 (void) {
   for (;;) {
     lock_mutex (MUTEX, RV_PRIVATE);

kernel/proc/mutex.c

@@ -93,6 +93,32 @@ bool proc_create_resource_mutex (struct proc_mutex* mutex) {
 
 void proc_cleanup_resource_mutex (struct proc* proc, struct proc_resource* resource) {
   struct proc_mutex* mutex = &resource->u.mutex;
+  spin_lock_ctx_t ctxmt, ctxsq;
+
+  spin_lock (&mutex->resource->lock, &ctxmt);
+  spin_lock (&mutex->suspension_q.lock, &ctxsq);
+
+  while (mutex->suspension_q.proc_list != NULL) {
+    struct list_node_link* node = mutex->suspension_q.proc_list;
+    struct proc_sq_entry* sq_entry = list_entry (node, struct proc_sq_entry, sq_link);
+    struct proc* suspended_proc = sq_entry->proc;
+
+    /* we will relock during resume */
+    spin_unlock (&mutex->suspension_q.lock, &ctxsq);
+    spin_unlock (&mutex->resource->lock, &ctxmt);
+
+    proc_mutex_resume (suspended_proc, sq_entry);
+
+    /* reacquire */
+    spin_lock (&mutex->resource->lock, &ctxmt);
+    spin_lock (&mutex->suspension_q.lock, &ctxsq);
+  }
+
+  mutex->locked = false;
+  mutex->owner = NULL;
+
+  spin_unlock (&mutex->suspension_q.lock, &ctxsq);
+  spin_unlock (&mutex->resource->lock, &ctxmt);
 }
 
 void proc_mutex_lock (struct proc* proc, struct proc_mutex* mutex) {