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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.
This commit is contained in:
Olivier Houchard 2019-04-17 19:13:07 +02:00 committed by Olivier Houchard
parent 5c964f7b42
commit 4a1be0c6d6
1 changed files with 1 additions and 10 deletions
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11
include/proto/task.h
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@ -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);
}