1 files changed, 62 insertions, 4 deletions

diff --git a/kernel/kthread.c b/kernel/kthread.c
index ba3992c8c375..8af313081b0d 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -20,7 +20,6 @@
 #include <linux/freezer.h>
 #include <linux/ptrace.h>
 #include <linux/uaccess.h>
-#include <linux/cgroup.h>
 #include <trace/events/sched.h>
 
 static DEFINE_SPINLOCK(kthread_create_lock);
@@ -47,6 +46,9 @@ struct kthread {
         void *data;
         struct completion parked;
         struct completion exited;
+#ifdef CONFIG_BLK_CGROUP
+        struct cgroup_subsys_state *blkcg_css;
+#endif
 };
 
 enum KTHREAD_BITS {
@@ -74,11 +76,17 @@ static inline struct kthread *to_kthread(struct task_struct *k)
 
 void free_kthread_struct(struct task_struct *k)
 {
+        struct kthread *kthread;
+
         /*
          * Can be NULL if this kthread was created by kernel_thread()
          * or if kmalloc() in kthread() failed.
          */
-        kfree(to_kthread(k));
+        kthread = to_kthread(k);
+#ifdef CONFIG_BLK_CGROUP
+        WARN_ON_ONCE(kthread && kthread->blkcg_css);
+#endif
+        kfree(kthread);
 }
 
 /**
@@ -196,7 +204,7 @@ static int kthread(void *_create)
         struct kthread *self;
         int ret;
 
-        self = kmalloc(sizeof(*self), GFP_KERNEL);
+        self = kzalloc(sizeof(*self), GFP_KERNEL);
         set_kthread_struct(self);
 
         /* If user was SIGKILLed, I release the structure. */
@@ -212,7 +220,6 @@ static int kthread(void *_create)
                 do_exit(-ENOMEM);
         }
 
-        self->flags = 0;
         self->data = data;
         init_completion(&self->exited);
         init_completion(&self->parked);
@@ -1152,3 +1159,54 @@ void kthread_destroy_worker(struct kthread_worker *worker)
         kfree(worker);
 }
 EXPORT_SYMBOL(kthread_destroy_worker);
+
+#ifdef CONFIG_BLK_CGROUP
+/**
+ * kthread_associate_blkcg - associate blkcg to current kthread
+ * @css: the cgroup info
+ *
+ * Current thread must be a kthread. The thread is running jobs on behalf of
+ * other threads. In some cases, we expect the jobs attach cgroup info of
+ * original threads instead of that of current thread. This function stores
+ * original thread's cgroup info in current kthread context for later
+ * retrieval.
+ */
+void kthread_associate_blkcg(struct cgroup_subsys_state *css)
+{
+        struct kthread *kthread;
+
+        if (!(current->flags & PF_KTHREAD))
+                return;
+        kthread = to_kthread(current);
+        if (!kthread)
+                return;
+
+        if (kthread->blkcg_css) {
+                css_put(kthread->blkcg_css);
+                kthread->blkcg_css = NULL;
+        }
+        if (css) {
+                css_get(css);
+                kthread->blkcg_css = css;
+        }
+}
+EXPORT_SYMBOL(kthread_associate_blkcg);
+
+/**
+ * kthread_blkcg - get associated blkcg css of current kthread
+ *
+ * Current thread must be a kthread.
+ */
+struct cgroup_subsys_state *kthread_blkcg(void)
+{
+        struct kthread *kthread;
+
+        if (current->flags & PF_KTHREAD) {
+                kthread = to_kthread(current);
+                if (kthread)
+                        return kthread->blkcg_css;
+        }
+        return NULL;
+}
+EXPORT_SYMBOL(kthread_blkcg);
+#endif