linux-kernel - [PATCH 5/8] cgroup: cosmetic updates to rebind

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Date:	Tue, 11 Aug 2015 13:58:06 -0400
From:	Tejun Heo <tj@...nel.org>
To:	hannes@...xchg.org, lizefan@...wei.com
Cc:	mhocko@...nel.org, cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org, Tejun Heo <tj@...nel.org>
Subject: [PATCH 5/8] cgroup: cosmetic updates to rebind_subsystems()

* Use local variables @scgrp and @dcgrp for @src_root->cgrp and
  @dst_root->cgrp respectively.

* Use initializers to set @src_root and @css in the inner bind loop.

Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: Li Zefan <lizefan@...wei.com>
Cc: Johannes Weiner <hannes@...xchg.org>
---
 kernel/cgroup.c | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 5e5a4e0..67d2ba3 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1271,6 +1271,7 @@ static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask)
 static int rebind_subsystems(struct cgroup_root *dst_root,
 			     unsigned long ss_mask)
 {
+	struct cgroup *dcgrp = &dst_root->cgrp;
 	struct cgroup_subsys *ss;
 	unsigned long tmp_ss_mask;
 	int ssid, i, ret;
@@ -1292,7 +1293,7 @@ static int rebind_subsystems(struct cgroup_root *dst_root,
 	if (dst_root == &cgrp_dfl_root)
 		tmp_ss_mask &= ~cgrp_dfl_root_inhibit_ss_mask;
 
-	ret = cgroup_populate_dir(&dst_root->cgrp, tmp_ss_mask);
+	ret = cgroup_populate_dir(dcgrp, tmp_ss_mask);
 	if (ret) {
 		if (dst_root != &cgrp_dfl_root)
 			return ret;
@@ -1318,42 +1319,40 @@ static int rebind_subsystems(struct cgroup_root *dst_root,
 		cgroup_clear_dir(&ss->root->cgrp, 1 << ssid);
 
 	for_each_subsys_which(ss, ssid, &ss_mask) {
-		struct cgroup_root *src_root;
-		struct cgroup_subsys_state *css;
+		struct cgroup_root *src_root = ss->root;
+		struct cgroup *scgrp = &src_root->cgrp;
+		struct cgroup_subsys_state *css = cgroup_css(scgrp, ss);
 		struct css_set *cset;
 
-		src_root = ss->root;
-		css = cgroup_css(&src_root->cgrp, ss);
-
-		WARN_ON(!css || cgroup_css(&dst_root->cgrp, ss));
+		WARN_ON(!css || cgroup_css(dcgrp, ss));
 
-		RCU_INIT_POINTER(src_root->cgrp.subsys[ssid], NULL);
-		rcu_assign_pointer(dst_root->cgrp.subsys[ssid], css);
+		RCU_INIT_POINTER(scgrp->subsys[ssid], NULL);
+		rcu_assign_pointer(dcgrp->subsys[ssid], css);
 		ss->root = dst_root;
-		css->cgroup = &dst_root->cgrp;
+		css->cgroup = dcgrp;
 
 		down_write(&css_set_rwsem);
 		hash_for_each(css_set_table, i, cset, hlist)
 			list_move_tail(&cset->e_cset_node[ss->id],
-				       &dst_root->cgrp.e_csets[ss->id]);
+				       &dcgrp->e_csets[ss->id]);
 		up_write(&css_set_rwsem);
 
 		src_root->subsys_mask &= ~(1 << ssid);
-		src_root->cgrp.subtree_control &= ~(1 << ssid);
-		cgroup_refresh_child_subsys_mask(&src_root->cgrp);
+		scgrp->subtree_control &= ~(1 << ssid);
+		cgroup_refresh_child_subsys_mask(scgrp);
 
 		/* default hierarchy doesn't enable controllers by default */
 		dst_root->subsys_mask |= 1 << ssid;
 		if (dst_root != &cgrp_dfl_root) {
-			dst_root->cgrp.subtree_control |= 1 << ssid;
-			cgroup_refresh_child_subsys_mask(&dst_root->cgrp);
+			dcgrp->subtree_control |= 1 << ssid;
+			cgroup_refresh_child_subsys_mask(dcgrp);
 		}
 
 		if (ss->bind)
 			ss->bind(css);
 	}
 
-	kernfs_activate(dst_root->cgrp.kn);
+	kernfs_activate(dcgrp->kn);
 	return 0;
 }
 
-- 
2.4.3

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