[PATCH 2/2] workqueue: update cpumask at CPU_ONLINE if necessary

[Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

In some case, cpu's numa affinity will be changed in cpu_up().
It happens after a new node is onlined.
(in x86, online cpus are tied to onlined node at boot.
 so, if memory is added later, cpu mapping can be changed at cpu_up()

Although wq_numa_possible_cpumask at el. are maintained against
node hotplug, this case should be handled.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
 kernel/workqueue.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index f6ad05a..59d8be5 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4618,6 +4618,27 @@ void workqueue_node_unregister(int node)
 	mutex_unlock(&wq_pool_mutex);
 }
 
+static void workqueue_may_update_numa_affinity(int cpu)
+{
+	int curnode = cpu_to_node(cpu);
+	int node;
+
+	if (likely(cpumask_test_cpu(cpu, wq_numa_possible_cpumask[curnode])))
+		return;
+
+	/* cpu<->node relationship is changed in cpu_up() */
+	for_each_node_state(node, N_POSSIBLE)
+		cpumask_clear_cpu(cpu, wq_numa_possible_cpumask[node]);
+
+	workqueue_update_cpu_numa_affinity(cpu, curnode);
+}
+#else
+
+static void workqueue_may_update_numa_affinity(int cpu)
+{
+	return;
+}
+
 #endif
 
 /*
@@ -4647,6 +4668,8 @@ static int workqueue_cpu_up_callback(struct notifier_block *nfb,
 	case CPU_ONLINE:
 		mutex_lock(&wq_pool_mutex);
 
+		workqueue_may_update_numa_affinity(cpu);
+
 		for_each_pool(pool, pi) {
 			mutex_lock(&pool->attach_mutex);
 
-- 
1.8.3.1