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authorTejun Heo <tj@kernel.org>2016-03-03 09:58:00 -0500
committerTejun Heo <tj@kernel.org>2016-03-03 09:58:00 -0500
commitf7b2814bb9b6cb1d69333e1592c702260fcb4184 (patch)
treec3f3d5c0c1e96cc170d8fa40d9ef997b5123e5e3 /kernel/cgroup.c
parent15a27c362d54378f17ec078579b2f6af88495a3f (diff)
downloadlinux-sh-f7b2814bb9b6cb1d69333e1592c702260fcb4184.tar.gz
cgroup: factor out cgroup_{apply|finalize}_control() from cgroup_subtree_control_write()
Factor out cgroup_{apply|finalize}_control() so that control mask update can be done in several simple steps. This patch doesn't introduce behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c81
1 files changed, 58 insertions, 23 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 452a90e455fa..2adf0433a3cf 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3169,6 +3169,62 @@ static void cgroup_apply_control_disable(struct cgroup *cgrp)
}
}
+/**
+ * cgroup_apply_control - apply control mask updates to the subtree
+ * @cgrp: root of the target subtree
+ *
+ * subsystems can be enabled and disabled in a subtree using the following
+ * steps.
+ *
+ * 1. Call cgroup_save_control() to stash the current state.
+ * 2. Update ->subtree_control masks in the subtree as desired.
+ * 3. Call cgroup_apply_control() to apply the changes.
+ * 4. Optionally perform other related operations.
+ * 5. Call cgroup_finalize_control() to finish up.
+ *
+ * This function implements step 3 and propagates the mask changes
+ * throughout @cgrp's subtree, updates csses accordingly and perform
+ * process migrations.
+ */
+static int cgroup_apply_control(struct cgroup *cgrp)
+{
+ int ret;
+
+ cgroup_propagate_control(cgrp);
+
+ ret = cgroup_apply_control_enable(cgrp);
+ if (ret)
+ return ret;
+
+ /*
+ * At this point, cgroup_e_css() results reflect the new csses
+ * making the following cgroup_update_dfl_csses() properly update
+ * css associations of all tasks in the subtree.
+ */
+ ret = cgroup_update_dfl_csses(cgrp);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+/**
+ * cgroup_finalize_control - finalize control mask update
+ * @cgrp: root of the target subtree
+ * @ret: the result of the update
+ *
+ * Finalize control mask update. See cgroup_apply_control() for more info.
+ */
+static void cgroup_finalize_control(struct cgroup *cgrp, int ret)
+{
+ if (ret) {
+ cgroup_restore_control(cgrp);
+ cgroup_propagate_control(cgrp);
+ }
+
+ cgroup_apply_control_disable(cgrp);
+}
+
/* change the enabled child controllers for a cgroup in the default hierarchy */
static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
char *buf, size_t nbytes,
@@ -3264,36 +3320,15 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
cgrp->subtree_control |= enable;
cgrp->subtree_control &= ~disable;
- cgroup_propagate_control(cgrp);
+ ret = cgroup_apply_control(cgrp);
- ret = cgroup_apply_control_enable(cgrp);
- if (ret)
- goto err_undo_css;
-
- /*
- * At this point, cgroup_e_css() results reflect the new csses
- * making the following cgroup_update_dfl_csses() properly update
- * css associations of all tasks in the subtree.
- */
- ret = cgroup_update_dfl_csses(cgrp);
- if (ret)
- goto err_undo_css;
-
- /* all tasks are migrated out of disabled csses, commit disable */
- cgroup_apply_control_disable(cgrp);
+ cgroup_finalize_control(cgrp, ret);
kernfs_activate(cgrp->kn);
ret = 0;
out_unlock:
cgroup_kn_unlock(of->kn);
return ret ?: nbytes;
-
-err_undo_css:
- /* restore masks and shoot down new csses */
- cgroup_restore_control(cgrp);
- cgroup_apply_control_disable(cgrp);
-
- goto out_unlock;
}
static int cgroup_events_show(struct seq_file *seq, void *v)