[PATCH v2 09/12] cpuset: refactor cpuset_hotplug_update_tasks()

From: Li Zefan
Date: Fri Oct 11 2013 - 05:51:44 EST


We mix the handling for both sane_behavior and !sane_behavior in the
same function, and it's quite messy, so split into two functions.

Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx>
---
kernel/cpuset.c | 118 ++++++++++++++++++++++++++++++--------------------------
1 file changed, 63 insertions(+), 55 deletions(-)

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index e47115e..cefc8f4 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -2186,6 +2186,65 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
}
}

+static void hotplug_update_tasks_insane(struct cpuset *cs,
+ struct cpumask *off_cpus,
+ nodemask_t *off_mems)
+{
+ bool is_empty;
+
+ mutex_lock(&callback_mutex);
+ cpumask_andnot(cs->cpus_allowed, cs->cpus_allowed, off_cpus);
+ cpumask_andnot(cs->effective_cpus, cs->effective_cpus, off_cpus);
+ nodes_andnot(cs->mems_allowed, cs->mems_allowed, *off_mems);
+ nodes_andnot(cs->effective_mems, cs->effective_mems, *off_mems);
+ mutex_unlock(&callback_mutex);
+
+ /*
+ * Don't call update_tasks_cpumask() if the cpuset becomes empty,
+ * as the tasks will be migratecd to an ancestor.
+ */
+ if (!cpumask_empty(off_cpus) && !cpumask_empty(cs->cpus_allowed))
+ update_tasks_cpumask(cs, NULL);
+ if (!nodes_empty(*off_mems) && !nodes_empty(cs->mems_allowed))
+ update_tasks_nodemask(cs, NULL);
+
+ is_empty = cpumask_empty(cs->cpus_allowed) ||
+ nodes_empty(cs->mems_allowed);
+
+ mutex_unlock(&cpuset_mutex);
+
+ /*
+ * Move tasks to the nearest ancestor with execution resources,
+ * This is full cgroup operation which will also call back into
+ * cpuset. Should be done outside any lock.
+ */
+ if (is_empty)
+ remove_tasks_in_empty_cpuset(cs);
+
+ mutex_lock(&cpuset_mutex);
+}
+
+static void hotplug_update_tasks_sane(struct cpuset *cs,
+ struct cpumask *off_cpus,
+ nodemask_t *off_mems)
+{
+ mutex_lock(&callback_mutex);
+ cpumask_andnot(cs->effective_cpus, cs->effective_cpus, off_cpus);
+ if (cpumask_empty(cs->effective_cpus))
+ cpumask_copy(cs->effective_cpus,
+ parent_cs(cs)->effective_cpus);
+
+ nodes_andnot(cs->effective_mems, cs->effective_mems, *off_mems);
+ if (nodes_empty(cs->effective_mems))
+ cs->effective_mems = parent_cs(cs)->effective_mems;
+ mutex_unlock(&callback_mutex);
+
+ if (!cpumask_empty(off_cpus))
+ update_tasks_cpumask(cs, NULL);
+ if (!nodes_empty(*off_mems))
+ update_tasks_nodemask(cs, NULL);
+}
+
/**
* cpuset_hotplug_update_tasks - update tasks in a cpuset for hotunplug
* @cs: cpuset in interest
@@ -2198,9 +2257,6 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs)
{
static cpumask_t off_cpus;
static nodemask_t off_mems;
- bool is_empty;
- bool sane = cgroup_sane_behavior(cs->css.cgroup);
-
retry:
wait_event(cpuset_attach_wq, cs->attach_in_progress == 0);

@@ -2218,60 +2274,12 @@ retry:
cpumask_andnot(&off_cpus, cs->effective_cpus, top_cpuset.effective_cpus);
nodes_andnot(off_mems, cs->effective_mems, top_cpuset.effective_mems);

- mutex_lock(&callback_mutex);
- if (!sane)
- cpumask_andnot(cs->cpus_allowed, cs->cpus_allowed, &off_cpus);
-
- /* Inherit the effective mask of the parent, if it becomes empty. */
- cpumask_andnot(cs->effective_cpus, cs->effective_cpus, &off_cpus);
- if (sane && cpumask_empty(cs->effective_cpus))
- cpumask_copy(cs->effective_cpus, parent_cs(cs)->effective_cpus);
- mutex_unlock(&callback_mutex);
-
- /*
- * If sane_behavior flag is set, we need to update tasks' cpumask
- * for empty cpuset to take on ancestor's cpumask. Otherwise, don't
- * call update_tasks_cpumask() if the cpuset becomes empty, as
- * the tasks in it will be migrated to an ancestor.
- */
- if ((sane && cpumask_empty(cs->cpus_allowed)) ||
- (!cpumask_empty(&off_cpus) && !cpumask_empty(cs->cpus_allowed)))
- update_tasks_cpumask(cs, NULL);
-
- mutex_lock(&callback_mutex);
- if (!sane)
- nodes_andnot(cs->mems_allowed, cs->mems_allowed, off_mems);
-
- /* Inherit the effective mask of the parent, if it becomes empty */
- nodes_andnot(cs->effective_mems, cs->effective_mems, off_mems);
- if (sane && nodes_empty(cs->effective_mems))
- cs->effective_mems = parent_cs(cs)->effective_mems;
- mutex_unlock(&callback_mutex);
-
- /*
- * If sane_behavior flag is set, we need to update tasks' nodemask
- * for empty cpuset to take on ancestor's nodemask. Otherwise, don't
- * call update_tasks_nodemask() if the cpuset becomes empty, as
- * the tasks in it will be migratd to an ancestor.
- */
- if ((sane && nodes_empty(cs->mems_allowed)) ||
- (!nodes_empty(off_mems) && !nodes_empty(cs->mems_allowed)))
- update_tasks_nodemask(cs, NULL);
-
- is_empty = cpumask_empty(cs->cpus_allowed) ||
- nodes_empty(cs->mems_allowed);
+ if (cgroup_sane_behavior(cs->css.cgroup))
+ hotplug_update_tasks_sane(cs, &off_cpus, &off_mems);
+ else
+ hotplug_update_tasks_insane(cs, &off_cpus, &off_mems);

mutex_unlock(&cpuset_mutex);
-
- /*
- * If sane_behavior flag is set, we'll keep tasks in empty cpusets.
- *
- * Otherwise move tasks to the nearest ancestor with execution
- * resources. This is full cgroup operation which will
- * also call back into cpuset. Should be done outside any lock.
- */
- if (!sane && is_empty)
- remove_tasks_in_empty_cpuset(cs);
}

/**
--
1.8.0.2

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