[PATCH 1/4] workqueue: introduce get_pwq_unlocked()

From: Lai Jiangshan
Date: Wed Jun 03 2015 - 11:02:37 EST


attrs management code may reuse existed pwq and it has open code
to do "lock();get_pwq();unlock()", we move this open code into
get_pwq_unlocked().

get_pwq_unlocked() will also be used in later patches to allow
apply_wqattrs_prepare() to resue the original default or per-node pwq.

Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
---
kernel/workqueue.c | 31 ++++++++++++++++++++-----------
1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index afe7c53..6aa9bd5 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1065,6 +1065,20 @@ static void put_pwq(struct pool_workqueue *pwq)
}

/**
+ * get_pwq_unlocked - get_pwq() with surrounding pool lock/unlock
+ * @pwq: pool_workqueue to get (should not %NULL)
+ *
+ * get_pwq() with locking. The caller should have at least an owned
+ * reference on @pwq to match the guarantees required by get_pwq().
+ */
+static void get_pwq_unlocked(struct pool_workqueue *pwq)
+{
+ spin_lock_irq(&pwq->pool->lock);
+ get_pwq(pwq);
+ spin_unlock_irq(&pwq->pool->lock);
+}
+
+/**
* put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock
* @pwq: pool_workqueue to put (can be %NULL)
*
@@ -3715,7 +3729,9 @@ static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask))
return;
} else {
- goto use_dfl_pwq;
+ pwq = wq->dfl_pwq;
+ get_pwq_unlocked(pwq);
+ goto install;
}

/* create a new pwq */
@@ -3723,21 +3739,14 @@ static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
if (!pwq) {
pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",
wq->name);
- goto use_dfl_pwq;
+ pwq = wq->dfl_pwq;
+ get_pwq_unlocked(pwq);
}

+install:
/* Install the new pwq. */
mutex_lock(&wq->mutex);
old_pwq = numa_pwq_tbl_install(wq, node, pwq);
- goto out_unlock;
-
-use_dfl_pwq:
- mutex_lock(&wq->mutex);
- spin_lock_irq(&wq->dfl_pwq->pool->lock);
- get_pwq(wq->dfl_pwq);
- spin_unlock_irq(&wq->dfl_pwq->pool->lock);
- old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq);
-out_unlock:
mutex_unlock(&wq->mutex);
put_pwq_unlocked(old_pwq);
}
--
2.1.0

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