busy_worker_rebind_fn() can't return until all idle workers are rebound.
This order is ensured by rebind_workers() currently.
We use mutex_lock(&worker->pool->manager_mutex) to wait for all idle workers
to be rebound. this is an explicit way and it will ease the pain of
the rebind_workers().
The sleeping mutex_lock(&worker->pool->manager_mutex) must be put in the top of
busy_worker_rebind_fn(), because this busy worker thread can sleep
before the WORKER_REBIND is cleared, but can't sleep after
the WORKER_REBIND cleared.
It adds a small overhead to the unlikely path.
Signed-off-by: Lai Jiangshan <la...@cn.fujitsu.com>
---
kernel/workqueue.c | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index d88aa2e..719d6ec 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1376,9 +1376,15 @@ static void busy_worker_rebind_fn(struct work_struct
*work)
struct worker *worker = container_of(work, struct worker, rebind_work);
struct global_cwq *gcwq = worker->pool->gcwq;
+ /*
+ * Waiting all idle workers are rebound by competing on
+ * pool->manager_mutex.
+ */
+ mutex_lock(&worker->pool->manager_mutex);
+
if (worker_maybe_bind_and_lock(worker))
worker_clr_flags(worker, WORKER_REBIND);
-
+ non_manager_role_manager_mutex_unlock(worker->pool);
spin_unlock_irq(&gcwq->lock);
}
--
1.7.4.4
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