locking, sched, cgroups: Annotate release_list_lock as raw

The release_list_lock can be taken in atomic context and therefore
cannot be preempted on -rt - annotate it.

In mainline this change documents the low level nature of
the lock - otherwise there's no functional difference. Lockdep
and Sparse checking will work as usual.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/cgroup.c

@@ -265,7 +265,7 @@ list_for_each_entry(_root, &roots, root_list)
 /* the list of cgroups eligible for automatic release. Protected by
  * release_list_lock */
 static LIST_HEAD(release_list);
-static DEFINE_SPINLOCK(release_list_lock);
+static DEFINE_RAW_SPINLOCK(release_list_lock);
 static void cgroup_release_agent(struct work_struct *work);
 static DECLARE_WORK(release_agent_work, cgroup_release_agent);
 static void check_for_release(struct cgroup *cgrp);
@@ -4014,11 +4014,11 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
 	finish_wait(&cgroup_rmdir_waitq, &wait);
 	clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
 
-	spin_lock(&release_list_lock);
+	raw_spin_lock(&release_list_lock);
 	set_bit(CGRP_REMOVED, &cgrp->flags);
 	if (!list_empty(&cgrp->release_list))
 		list_del_init(&cgrp->release_list);
-	spin_unlock(&release_list_lock);
+	raw_spin_unlock(&release_list_lock);
 
 	cgroup_lock_hierarchy(cgrp->root);
 	/* delete this cgroup from parent->children */
@@ -4671,13 +4671,13 @@ static void check_for_release(struct cgroup *cgrp)
 		 * already queued for a userspace notification, queue
 		 * it now */
 		int need_schedule_work = 0;
-		spin_lock(&release_list_lock);
+		raw_spin_lock(&release_list_lock);
 		if (!cgroup_is_removed(cgrp) &&
 		    list_empty(&cgrp->release_list)) {
 			list_add(&cgrp->release_list, &release_list);
 			need_schedule_work = 1;
 		}
-		spin_unlock(&release_list_lock);
+		raw_spin_unlock(&release_list_lock);
 		if (need_schedule_work)
 			schedule_work(&release_agent_work);
 	}
@@ -4729,7 +4729,7 @@ static void cgroup_release_agent(struct work_struct *work)
 {
 	BUG_ON(work != &release_agent_work);
 	mutex_lock(&cgroup_mutex);
-	spin_lock(&release_list_lock);
+	raw_spin_lock(&release_list_lock);
 	while (!list_empty(&release_list)) {
 		char *argv[3], *envp[3];
 		int i;
@@ -4738,7 +4738,7 @@ static void cgroup_release_agent(struct work_struct *work)
 						    struct cgroup,
 						    release_list);
 		list_del_init(&cgrp->release_list);
-		spin_unlock(&release_list_lock);
+		raw_spin_unlock(&release_list_lock);
 		pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 		if (!pathbuf)
 			goto continue_free;
@@ -4768,9 +4768,9 @@ static void cgroup_release_agent(struct work_struct *work)
  continue_free:
 		kfree(pathbuf);
 		kfree(agentbuf);
-		spin_lock(&release_list_lock);
+		raw_spin_lock(&release_list_lock);
 	}
-	spin_unlock(&release_list_lock);
+	raw_spin_unlock(&release_list_lock);
 	mutex_unlock(&cgroup_mutex);
 }