MEDIUM: tasks: No longer use rq.node.leaf_p as a lock.

Now that we have the warranty that a task won't be added in the runqueue
while the TASK_QUEUED or the TASK_RUNNING flag is set, don't bother trying
to lock the task by setting leaf_p to 0x1 while inserting it in the runqueue
or having it in the tasklet_list, as nobody else will attempt to add it.

diff --git a/include/proto/task.h b/include/proto/task.h
index 4de7de64807edb375adc7a837ce98a186f1ebbf1..1a89f2038b8023f2a3a89f828f23e127081d0600 100644 (file)
--- a/include/proto/task.h
+++ b/include/proto/task.h
@@ -122,7 +122,7 @@ static inline int task_in_rq(struct task *t)
        /* Check if leaf_p is NULL, in case he's not in the runqueue, and if
         * it's not 0x1, which would mean it's in the tasklet list.
         */
-       return t->rq.node.leaf_p != NULL && t->rq.node.leaf_p != (void *)0x1;
+       return t->rq.node.leaf_p != NULL;
 }
 
 /* return 0 if task is in wait queue, otherwise non-zero */
@@ -250,14 +250,7 @@ static inline void tasklet_wakeup(struct tasklet *tl)
 static inline void task_insert_into_tasklet_list(struct task *t)
 {
        struct tasklet *tl;
-       void *expected = NULL;
 
-       /* Protect ourself against anybody trying to insert the task into
-        * another runqueue. We set leaf_p to 0x1 to indicate that the node is
-        * not in a tree but that it's in the tasklet list. See task_in_rq().
-        */
-       if (unlikely(!_HA_ATOMIC_CAS(&t->rq.node.leaf_p, &expected, (void *)0x1)))
-               return;
        _HA_ATOMIC_ADD(&tasks_run_queue, 1);
        task_per_thread[tid].task_list_size++;
        tl = (struct tasklet *)t;
@@ -271,8 +264,6 @@ static inline void __task_remove_from_tasklet_list(struct task *t)
 {
        LIST_DEL_INIT(&((struct tasklet *)t)->list);
        task_per_thread[tid].task_list_size--;
-       if (!TASK_IS_TASKLET(t))
-               _HA_ATOMIC_STORE(&t->rq.node.leaf_p, NULL); // was 0x1
        _HA_ATOMIC_SUB(&tasks_run_queue, 1);
 }