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@xxxxxxxxxx>
---
kernel/cgroup.c | 81 +++++++++++++++++++++++++++++++++++++++++----------------
1 file changed, 58 insertions(+), 23 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 86d7bcb..a1f82fa 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3164,6 +3164,62 @@ 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,
@@ -3262,36 +3318,15 @@ 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)
--
2.5.0
--
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