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Date: Wed, 7 May 2014 18:36:59 +0200
From: Frederic Weisbecker <fweisbec@...il.com>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>,
Christoph Lameter <cl@...ux.com>,
Kevin Hilman <khilman@...aro.org>,
Lai Jiangshan <laijs@...fujitsu.com>,
Mike Galbraith <bitbucket@...ine.de>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Tejun Heo <tj@...nel.org>,
Viresh Kumar <viresh.kumar@...aro.org>
Subject: [PATCH 4/6] workqueue: Split apply attrs code from its locking
In order to allow overriding the unbound wqs low-level cpumask, we
need to be able to call apply_workqueue_attr() on all workqueues in
the pool list.
Now since traversing the pool list require to lock it, we can't currently
call apply_workqueue_attr() under the pool traversal.
So lets provide a version of apply_workqueue_attrs() that can be
called when the pool is already locked.
Suggested-by: Tejun Heo <tj@...nel.org>
Cc: Christoph Lameter <cl@...ux.com>
Cc: Kevin Hilman <khilman@...aro.org>
Cc: Lai Jiangshan <laijs@...fujitsu.com>
Cc: Mike Galbraith <bitbucket@...ine.de>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Tejun Heo <tj@...nel.org>
Cc: Viresh Kumar <viresh.kumar@...aro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
---
kernel/workqueue.c | 77 +++++++++++++++++++++++++++++++-----------------------
1 file changed, 44 insertions(+), 33 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 1252a8c..2aa296d 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3637,24 +3637,9 @@ static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq,
return old_pwq;
}
-/**
- * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
- * @wq: the target workqueue
- * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs()
- *
- * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA
- * machines, this function maps a separate pwq to each NUMA node with
- * possibles CPUs in @attrs->cpumask so that work items are affine to the
- * NUMA node it was issued on. Older pwqs are released as in-flight work
- * items finish. Note that a work item which repeatedly requeues itself
- * back-to-back will stay on its current pwq.
- *
- * Performs GFP_KERNEL allocations.
- *
- * Return: 0 on success and -errno on failure.
- */
-int apply_workqueue_attrs(struct workqueue_struct *wq,
- const struct workqueue_attrs *attrs)
+static int apply_workqueue_attrs_locked(struct workqueue_struct *wq,
+ const struct workqueue_attrs *attrs,
+ cpumask_var_t unbounds_cpumask)
{
struct workqueue_attrs *new_attrs, *tmp_attrs;
struct pool_workqueue **pwq_tbl, *dfl_pwq;
@@ -3676,7 +3661,7 @@ int apply_workqueue_attrs(struct workqueue_struct *wq,
/* make a copy of @attrs and sanitize it */
copy_workqueue_attrs(new_attrs, attrs);
- cpumask_and(new_attrs->cpumask, new_attrs->cpumask, wq_unbound_cpumask);
+ cpumask_and(new_attrs->cpumask, new_attrs->cpumask, unbounds_cpumask);
/*
* We may create multiple pwqs with differing cpumasks. Make a
@@ -3686,15 +3671,6 @@ int apply_workqueue_attrs(struct workqueue_struct *wq,
copy_workqueue_attrs(tmp_attrs, new_attrs);
/*
- * CPUs should stay stable across pwq creations and installations.
- * Pin CPUs, determine the target cpumask for each node and create
- * pwqs accordingly.
- */
- get_online_cpus();
-
- mutex_lock(&wq_pool_mutex);
-
- /*
* If something goes wrong during CPU up/down, we'll fall back to
* the default pwq covering whole @attrs->cpumask. Always create
* it even if we don't use it immediately.
@@ -3714,8 +3690,6 @@ int apply_workqueue_attrs(struct workqueue_struct *wq,
}
}
- mutex_unlock(&wq_pool_mutex);
-
/* all pwqs have been created successfully, let's install'em */
mutex_lock(&wq->mutex);
@@ -3736,7 +3710,6 @@ int apply_workqueue_attrs(struct workqueue_struct *wq,
put_pwq_unlocked(pwq_tbl[node]);
put_pwq_unlocked(dfl_pwq);
- put_online_cpus();
ret = 0;
/* fall through */
out_free:
@@ -3750,14 +3723,52 @@ enomem_pwq:
for_each_node(node)
if (pwq_tbl && pwq_tbl[node] != dfl_pwq)
free_unbound_pwq(pwq_tbl[node]);
- mutex_unlock(&wq_pool_mutex);
- put_online_cpus();
enomem:
ret = -ENOMEM;
goto out_free;
}
/**
+ * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
+ * @wq: the target workqueue
+ * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs()
+ *
+ * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA
+ * machines, this function maps a separate pwq to each NUMA node with
+ * possibles CPUs in @attrs->cpumask so that work items are affine to the
+ * NUMA node it was issued on. Older pwqs are released as in-flight work
+ * items finish. Note that a work item which repeatedly requeues itself
+ * back-to-back will stay on its current pwq.
+ *
+ * Performs GFP_KERNEL allocations.
+ *
+ * Return: 0 on success and -errno on failure.
+ */
+int apply_workqueue_attrs(struct workqueue_struct *wq,
+ const struct workqueue_attrs *attrs)
+{
+ int ret;
+
+ /*
+ * CPUs should stay stable across pwq creations and installations.
+ * Pin CPUs, determine the target cpumask for each node and create
+ * pwqs accordingly.
+ */
+
+ get_online_cpus();
+ /*
+ * Lock for alloc_unbound_pwq()
+ */
+ mutex_lock(&wq_pool_mutex);
+ ret = apply_workqueue_attrs_locked(wq, attrs, wq_unbound_cpumask);
+ mutex_unlock(&wq_pool_mutex);
+ put_online_cpus();
+
+ return ret;
+}
+
+
+/**
* wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug
* @wq: the target workqueue
* @cpu: the CPU coming up or going down
--
1.8.3.1
--
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