From: Nick Piggin <nickpiggin@yahoo.com.au>
The SMT wake_idle code really wants to look at a non-local CPU's domain in
order to check for idle siblings.
So change the domain attachment code a little bit so we continue to hold a
runqueue's lock while attaching a new domain. This means the locking rules
have changed to: you may access your own domain without any lock, you must
hold a remote runqueue's lock in order to view its domain.
---
25-akpm/kernel/sched.c | 8 ++++----
1 files changed, 4 insertions(+), 4 deletions(-)
diff -puN kernel/sched.c~sched-smt-domain-race kernel/sched.c
--- 25/kernel/sched.c~sched-smt-domain-race 2004-04-29 00:28:02.004798336 -0700
+++ 25-akpm/kernel/sched.c 2004-04-29 00:28:02.020795904 -0700
@@ -3399,18 +3399,18 @@ static int migration_thread(void * data)
req = list_entry(head->next, migration_req_t, list);
list_del_init(head->next);
- spin_unlock(&rq->lock);
-
if (req->type == REQ_MOVE_TASK) {
+ spin_unlock(&rq->lock);
__migrate_task(req->task, req->dest_cpu);
+ local_irq_enable();
} else if (req->type == REQ_SET_DOMAIN) {
rq->sd = req->sd;
+ spin_unlock_irq(&rq->lock);
} else {
+ spin_unlock_irq(&rq->lock);
WARN_ON(1);
}
- local_irq_enable();
-
complete(&req->done);
}
return 0;
_