linux-kernel - [PATCH] cgroup: remove redundant assignment in while loop of cgroup_calc_subtree_ss

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Message-Id: <20190722113923.16914-1-rocking@whu.edu.cn>
Date:   Mon, 22 Jul 2019 19:39:23 +0800
From:   Peng Wang <rocking@....edu.cn>
To:     tj@...nel.org, lizefan@...wei.com, hannes@...xchg.org
Cc:     cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
        Peng Wang <rocking@....edu.cn>
Subject: [PATCH] cgroup: remove redundant assignment in while loop of cgroup_calc_subtree_ss_mask()

new_ss_mask is always not less than cur_ss_mask.
We don not need to update it with cur_ss_mask's value.

Signed-off-by: Peng Wang <rocking@....edu.cn>
---
 kernel/cgroup/cgroup.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 300b0c416341..2b8c39dabd26 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1520,7 +1520,7 @@ static umode_t cgroup_file_mode(const struct cftype *cft)
  */
 static u16 cgroup_calc_subtree_ss_mask(u16 subtree_control, u16 this_ss_mask)
 {
-	u16 cur_ss_mask = subtree_control;
+	u16 cur_ss_mask = subtree_control, new_ss_mask;
 	struct cgroup_subsys *ss;
 	int ssid;
 
@@ -1528,9 +1528,8 @@ static u16 cgroup_calc_subtree_ss_mask(u16 subtree_control, u16 this_ss_mask)
 
 	cur_ss_mask |= cgrp_dfl_implicit_ss_mask;
 
+	new_ss_mask = cur_ss_mask;
 	while (true) {
-		u16 new_ss_mask = cur_ss_mask;
-
 		do_each_subsys_mask(ss, ssid, cur_ss_mask) {
 			new_ss_mask |= ss->depends_on;
 		} while_each_subsys_mask();
-- 
2.19.1