1 files changed, 32 insertions, 0 deletions

diff --git a/litmus/locking.c b/litmus/locking.c
index 4881ca119acf..1d32dcd8e726 100644
--- a/litmus/locking.c
+++ b/litmus/locking.c
@@ -6,6 +6,7 @@
 
 #include <litmus/sched_plugin.h>
 #include <litmus/trace.h>
+#include <litmus/wait.h>
 
 static int create_generic_lock(void** obj_ref, obj_type_t type, void* __user arg);
 static int open_generic_lock(struct od_table_entry* entry, void* __user arg);
@@ -127,6 +128,37 @@ struct task_struct* __waitqueue_remove_first(wait_queue_head_t *wq)
         return(t);
 }
 
+unsigned int __add_wait_queue_prio_exclusive(
+        wait_queue_head_t* head,
+        prio_wait_queue_t *new)
+{
+        struct list_head *pos;
+        unsigned int passed = 0;
+
+        new->wq.flags |= WQ_FLAG_EXCLUSIVE;
+
+        /* find a spot where the new entry is less than the next */
+        list_for_each(pos, &head->task_list) {
+                prio_wait_queue_t* queued = list_entry(pos, prio_wait_queue_t,
+                                                       wq.task_list);
+
+                if (unlikely(lt_before(new->priority, queued->priority) ||
+                             (new->priority == queued->priority &&
+                              new->tie_breaker < queued->tie_breaker))) {
+                        /* pos is not less than new, thus insert here */
+                        __list_add(&new->wq.task_list, pos->prev, pos);
+                        goto out;
+                }
+                passed++;
+        }
+
+        /* if we get to this point either the list is empty or every entry
+         * queued element is less than new.
+         * Let's add new to the end. */
+        list_add_tail(&new->wq.task_list, &head->task_list);
+out:
+        return passed;
+}
 
 #else