cpuset: don't use cgroup_taskset_cur_css()

cgroup_taskset_cur_css() will be removed during the planned
resturcturing of migration path.  The only use of
cgroup_taskset_cur_css() is finding out the old cgroup_subsys_state of
the leader in cpuset_attach().  This usage can easily be removed by
remembering the old value from cpuset_can_attach().

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index bf20e4ac2f75da122ced42fa0870470a76cb52ac..d8bec21d7a11154d81fb0fc943ebacb316a1158d 100644 (file)
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1379,6 +1379,8 @@ static int fmeter_getrate(struct fmeter *fmp)
        return val;
 }
 
+static struct cpuset *cpuset_attach_old_cs;
+
 /* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */
 static int cpuset_can_attach(struct cgroup_subsys_state *css,
                             struct cgroup_taskset *tset)
@@ -1387,6 +1389,9 @@ static int cpuset_can_attach(struct cgroup_subsys_state *css,
        struct task_struct *task;
        int ret;
 
+       /* used later by cpuset_attach() */
+       cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset));
+
        mutex_lock(&cpuset_mutex);
 
        /*
@@ -1450,10 +1455,8 @@ static void cpuset_attach(struct cgroup_subsys_state *css,
        struct mm_struct *mm;
        struct task_struct *task;
        struct task_struct *leader = cgroup_taskset_first(tset);
-       struct cgroup_subsys_state *oldcss = cgroup_taskset_cur_css(tset,
-                                                       cpuset_cgrp_id);
        struct cpuset *cs = css_cs(css);
-       struct cpuset *oldcs = css_cs(oldcss);
+       struct cpuset *oldcs = cpuset_attach_old_cs;
        struct cpuset *cpus_cs = effective_cpumask_cpuset(cs);
        struct cpuset *mems_cs = effective_nodemask_cpuset(cs);