cgroup: refactor the cgroup_attach_lock code to make it clearer

Dynamic cgroup migration involving threadgroup locks can be in one of
two states: no lock held, or holding the global lock. Explicitly
declaring the different lock modes to make the code easier to
understand and facilitates future extensions of the lock modes.

Signed-off-by: Yi Tao <escape@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 7 insertions, 7 deletions

diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 0a23b65de013..852ebe7ca3a1 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -69,7 +69,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
 	int retval = 0;
 
 	cgroup_lock();
-	cgroup_attach_lock(true);
+	cgroup_attach_lock(CGRP_ATTACH_LOCK_GLOBAL);
 	for_each_root(root) {
 		struct cgroup *from_cgrp;
 
@@ -81,7 +81,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
 		if (retval)
 			break;
 	}
-	cgroup_attach_unlock(true);
+	cgroup_attach_unlock(CGRP_ATTACH_LOCK_GLOBAL);
 	cgroup_unlock();
 
 	return retval;
@@ -118,7 +118,7 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
 
 	cgroup_lock();
 
-	cgroup_attach_lock(true);
+	cgroup_attach_lock(CGRP_ATTACH_LOCK_GLOBAL);
 
 	/* all tasks in @from are being moved, all csets are source */
 	spin_lock_irq(&css_set_lock);
@@ -154,7 +154,7 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
 	} while (task && !ret);
 out_err:
 	cgroup_migrate_finish(&mgctx);
-	cgroup_attach_unlock(true);
+	cgroup_attach_unlock(CGRP_ATTACH_LOCK_GLOBAL);
 	cgroup_unlock();
 	return ret;
 }
@@ -503,13 +503,13 @@ static ssize_t __cgroup1_procs_write(struct kernfs_open_file *of,
 	struct task_struct *task;
 	const struct cred *cred, *tcred;
 	ssize_t ret;
-	bool locked;
+	enum cgroup_attach_lock_mode lock_mode;
 
 	cgrp = cgroup_kn_lock_live(of->kn, false);
 	if (!cgrp)
 		return -ENODEV;
 
-	task = cgroup_procs_write_start(buf, threadgroup, &locked);
+	task = cgroup_procs_write_start(buf, threadgroup, &lock_mode);
 	ret = PTR_ERR_OR_ZERO(task);
 	if (ret)
 		goto out_unlock;
@@ -532,7 +532,7 @@ static ssize_t __cgroup1_procs_write(struct kernfs_open_file *of,
 	ret = cgroup_attach_task(cgrp, task, threadgroup);
 
 out_finish:
-	cgroup_procs_write_finish(task, locked);
+	cgroup_procs_write_finish(task, lock_mode);
 out_unlock:
 	cgroup_kn_unlock(of->kn);