[PATCH 2/3] workqueue: Add an API to create a singlethreadworkqueue attached to the current task's cgroup

[Sridhar Samudrala]

Add a new kernel API to create a singlethread workqueue and attach it's
task to current task's cgroup and cpumask.

Signed-off-by: Sridhar Samudrala <sri@xxxxxxxxxx>

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 9466e86..6d6f301 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -211,6 +211,7 @@ __create_workqueue_key(const char *name, int singlethread,
 #define create_freezeable_workqueue(name) __create_workqueue((name), 1, 1, 0)
 #define create_singlethread_workqueue(name) __create_workqueue((name), 1, 0, 0)
 
+extern struct workqueue_struct *create_singlethread_workqueue_in_current_cg(char *name); 
 extern void destroy_workqueue(struct workqueue_struct *wq);
 
 extern int queue_work(struct workqueue_struct *wq, struct work_struct *work);
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 5bfb213..6ba226e 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -35,6 +35,7 @@
 #include <linux/lockdep.h>
 #define CREATE_TRACE_POINTS
 #include <trace/events/workqueue.h>
+#include <linux/cgroup.h>
 
 /*
  * The per-CPU workqueue (if single thread, we always use the first
@@ -193,6 +194,45 @@ static const struct cpumask *cpu_singlethread_map __read_mostly;
  */
 static cpumask_var_t cpu_populated_map __read_mostly;
 
+static struct task_struct *get_singlethread_wq_task(struct workqueue_struct *wq)
+{
+	return (per_cpu_ptr(wq->cpu_wq, singlethread_cpu))->thread;
+}
+
+/* Create a singlethread workqueue and attach it's task to the current task's
+ * cgroup and set it's cpumask to the current task's cpumask.
+ */
+struct workqueue_struct *create_singlethread_workqueue_in_current_cg(char *name)
+{
+	struct workqueue_struct *wq;
+	struct task_struct *task;
+	cpumask_var_t mask;
+
+	wq = create_singlethread_workqueue(name);
+	if (!wq)
+		goto out;
+
+	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
+		goto err;
+			
+	if (sched_getaffinity(current->pid, mask))
+		goto err;
+
+	task = get_singlethread_wq_task(wq);
+	if (sched_setaffinity(task->pid, mask))
+		goto err;
+
+	if (cgroup_attach_task_current_cg(task))
+		goto err;
+out:	
+	return wq;
+err:
+	destroy_workqueue(wq);
+	wq = NULL;
+	goto out;
+}
+EXPORT_SYMBOL_GPL(create_singlethread_workqueue_in_current_cg);
+
 /* If it's single threaded, it isn't in the list of workqueues. */
 static inline int is_wq_single_threaded(struct workqueue_struct *wq)
 {
	

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