cgroup: cgroup.{procs,threads} factor out common parts

The functions cgroup_threads_write and cgroup_procs_write are almost
identical. In order to reduce duplication, factor out the common code in
similar fashion we already do for other threadgroup/task functions. No
functional changes are intended.

Suggested-by: Hao Lee <haolee.swjtu@gmail.com>
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 613845769103cd36ab9ef9340b9dd90f5c20f5f9..f6279df507f4bd4b6434c0d63e66011fa594cba9 100644 (file)
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -4726,8 +4726,8 @@ static int cgroup_attach_permissions(struct cgroup *src_cgrp,
        return ret;
 }
 
-static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
-                                 char *buf, size_t nbytes, loff_t off)
+static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
+                                   bool threadgroup)
 {
        struct cgroup *src_cgrp, *dst_cgrp;
        struct task_struct *task;
@@ -4738,7 +4738,7 @@ static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
        if (!dst_cgrp)
                return -ENODEV;
 
-       task = cgroup_procs_write_start(buf, true, &locked);
+       task = cgroup_procs_write_start(buf, threadgroup, &locked);
        ret = PTR_ERR_OR_ZERO(task);
        if (ret)
                goto out_unlock;
@@ -4748,19 +4748,26 @@ static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
        src_cgrp = task_cgroup_from_root(task, &cgrp_dfl_root);
        spin_unlock_irq(&css_set_lock);
 
+       /* process and thread migrations follow same delegation rule */
        ret = cgroup_attach_permissions(src_cgrp, dst_cgrp,
-                                       of->file->f_path.dentry->d_sb, true);
+                                       of->file->f_path.dentry->d_sb, threadgroup);
        if (ret)
                goto out_finish;
 
-       ret = cgroup_attach_task(dst_cgrp, task, true);
+       ret = cgroup_attach_task(dst_cgrp, task, threadgroup);
 
 out_finish:
        cgroup_procs_write_finish(task, locked);
 out_unlock:
        cgroup_kn_unlock(of->kn);
 
-       return ret ?: nbytes;
+       return ret;
+}
+
+static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
+                                 char *buf, size_t nbytes, loff_t off)
+{
+       return __cgroup_procs_write(of, buf, true) ?: nbytes;
 }
 
 static void *cgroup_threads_start(struct seq_file *s, loff_t *pos)
@@ -4771,41 +4778,7 @@ static void *cgroup_threads_start(struct seq_file *s, loff_t *pos)
 static ssize_t cgroup_threads_write(struct kernfs_open_file *of,
                                    char *buf, size_t nbytes, loff_t off)
 {
-       struct cgroup *src_cgrp, *dst_cgrp;
-       struct task_struct *task;
-       ssize_t ret;
-       bool locked;
-
-       buf = strstrip(buf);
-
-       dst_cgrp = cgroup_kn_lock_live(of->kn, false);
-       if (!dst_cgrp)
-               return -ENODEV;
-
-       task = cgroup_procs_write_start(buf, false, &locked);
-       ret = PTR_ERR_OR_ZERO(task);
-       if (ret)
-               goto out_unlock;
-
-       /* find the source cgroup */
-       spin_lock_irq(&css_set_lock);
-       src_cgrp = task_cgroup_from_root(task, &cgrp_dfl_root);
-       spin_unlock_irq(&css_set_lock);
-
-       /* thread migrations follow the cgroup.procs delegation rule */
-       ret = cgroup_attach_permissions(src_cgrp, dst_cgrp,
-                                       of->file->f_path.dentry->d_sb, false);
-       if (ret)
-               goto out_finish;
-
-       ret = cgroup_attach_task(dst_cgrp, task, false);
-
-out_finish:
-       cgroup_procs_write_finish(task, locked);
-out_unlock:
-       cgroup_kn_unlock(of->kn);
-
-       return ret ?: nbytes;
+       return __cgroup_procs_write(of, buf, false) ?: nbytes;
 }
 
 /* cgroup core interface files for the default hierarchy */