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authorPrateek Sood <prsood@codeaurora.org>2020-01-24 20:37:29 +0530
committerTejun Heo <tj@kernel.org>2020-02-12 17:13:47 -0500
commita49e4629b5edf1db856de05fbf1aae05502ef1af (patch)
tree11eed372fa154e9be6144e790581102f0ec5f4a2 /kernel/cgroup
parent3010c5b9f5f476b35b24955f08a3a6c06ec8e878 (diff)
cpuset: Make cpuset hotplug synchronous
Convert cpuset_hotplug_workfn() into synchronous call for cpu hotplug path. For memory hotplug path it still gets queued as a work item. Since cpuset_hotplug_workfn() can be made synchronous for cpu hotplug path, it is not required to wait for cpuset hotplug while thawing processes. Signed-off-by: Prateek Sood <prsood@codeaurora.org> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cgroup')
-rw-r--r--kernel/cgroup/cpuset.c31
1 files changed, 19 insertions, 12 deletions
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 58f5073acff7..cafd4d2ff882 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -3101,7 +3101,7 @@ update_tasks:
}
/**
- * cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset
+ * cpuset_hotplug - handle CPU/memory hotunplug for a cpuset
*
* This function is called after either CPU or memory configuration has
* changed and updates cpuset accordingly. The top_cpuset is always
@@ -3116,7 +3116,7 @@ update_tasks:
* Note that CPU offlining during suspend is ignored. We don't modify
* cpusets across suspend/resume cycles at all.
*/
-static void cpuset_hotplug_workfn(struct work_struct *work)
+static void cpuset_hotplug(bool use_cpu_hp_lock)
{
static cpumask_t new_cpus;
static nodemask_t new_mems;
@@ -3201,25 +3201,32 @@ static void cpuset_hotplug_workfn(struct work_struct *work)
/* rebuild sched domains if cpus_allowed has changed */
if (cpus_updated || force_rebuild) {
force_rebuild = false;
- rebuild_sched_domains();
+ if (use_cpu_hp_lock)
+ rebuild_sched_domains();
+ else {
+ /* Acquiring cpu_hotplug_lock is not required.
+ * When cpuset_hotplug() is called in hotplug path,
+ * cpu_hotplug_lock is held by the hotplug context
+ * which is waiting for cpuhp_thread_fun to indicate
+ * completion of callback.
+ */
+ percpu_down_write(&cpuset_rwsem);
+ rebuild_sched_domains_locked();
+ percpu_up_write(&cpuset_rwsem);
+ }
}
free_cpumasks(NULL, ptmp);
}
-void cpuset_update_active_cpus(void)
+static void cpuset_hotplug_workfn(struct work_struct *work)
{
- /*
- * We're inside cpu hotplug critical region which usually nests
- * inside cgroup synchronization. Bounce actual hotplug processing
- * to a work item to avoid reverse locking order.
- */
- schedule_work(&cpuset_hotplug_work);
+ cpuset_hotplug(true);
}
-void cpuset_wait_for_hotplug(void)
+void cpuset_update_active_cpus(void)
{
- flush_work(&cpuset_hotplug_work);
+ cpuset_hotplug(false);
}
/*