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authorTejun Heo <tj@kernel.org>2014-02-12 09:29:50 -0500
committerTejun Heo <tj@kernel.org>2014-02-12 09:29:50 -0500
commite61734c55c24cdf11b07e52a74aec4dc4a7f4bd0 (patch)
treebab256faae539cd38840bfc886317f80385acae4 /kernel/cpuset.c
parent6f30558f37bfbd428e3854c2c34b5c32117c8f7e (diff)
cgroup: remove cgroup->name
cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Diffstat (limited to 'kernel/cpuset.c')
-rw-r--r--kernel/cpuset.c27
1 files changed, 13 insertions, 14 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 2d018c795fe..e97a6e88d03 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -2088,10 +2088,9 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
parent = parent_cs(parent);
if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) {
- rcu_read_lock();
- printk(KERN_ERR "cpuset: failed to transfer tasks out of empty cpuset %s\n",
- cgroup_name(cs->css.cgroup));
- rcu_read_unlock();
+ printk(KERN_ERR "cpuset: failed to transfer tasks out of empty cpuset ");
+ pr_cont_cgroup_name(cs->css.cgroup);
+ pr_cont("\n");
}
}
@@ -2619,19 +2618,17 @@ void cpuset_print_task_mems_allowed(struct task_struct *tsk)
/* Statically allocated to prevent using excess stack. */
static char cpuset_nodelist[CPUSET_NODELIST_LEN];
static DEFINE_SPINLOCK(cpuset_buffer_lock);
-
struct cgroup *cgrp = task_cs(tsk)->css.cgroup;
- rcu_read_lock();
spin_lock(&cpuset_buffer_lock);
nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
tsk->mems_allowed);
- printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n",
- tsk->comm, cgroup_name(cgrp), cpuset_nodelist);
+ printk(KERN_INFO "%s cpuset=", tsk->comm);
+ pr_cont_cgroup_name(cgrp);
+ pr_cont(" mems_allowed=%s\n", cpuset_nodelist);
spin_unlock(&cpuset_buffer_lock);
- rcu_read_unlock();
}
/*
@@ -2681,12 +2678,12 @@ int proc_cpuset_show(struct seq_file *m, void *unused_v)
{
struct pid *pid;
struct task_struct *tsk;
- char *buf;
+ char *buf, *p;
struct cgroup_subsys_state *css;
int retval;
retval = -ENOMEM;
- buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ buf = kmalloc(PATH_MAX, GFP_KERNEL);
if (!buf)
goto out;
@@ -2696,14 +2693,16 @@ int proc_cpuset_show(struct seq_file *m, void *unused_v)
if (!tsk)
goto out_free;
+ retval = -ENAMETOOLONG;
rcu_read_lock();
css = task_css(tsk, cpuset_cgrp_id);
- retval = cgroup_path(css->cgroup, buf, PAGE_SIZE);
+ p = cgroup_path(css->cgroup, buf, PATH_MAX);
rcu_read_unlock();
- if (retval < 0)
+ if (!p)
goto out_put_task;
- seq_puts(m, buf);
+ seq_puts(m, p);
seq_putc(m, '\n');
+ retval = 0;
out_put_task:
put_task_struct(tsk);
out_free: