cgroup: clean up cgroup_subsys names and initialization
cgroup_subsys is a bit messier than it needs to be.
* The name of a subsys can be different from its internal identifier
defined in cgroup_subsys.h. Most subsystems use the matching name
but three - cpu, memory and perf_event - use different ones.
* cgroup_subsys_id enums are postfixed with _subsys_id and each
cgroup_subsys is postfixed with _subsys. cgroup.h is widely
included throughout various subsystems, it doesn't and shouldn't
have claim on such generic names which don't have any qualifier
indicating that they belong to cgroup.
* cgroup_subsys->subsys_id should always equal the matching
cgroup_subsys_id enum; however, we require each controller to
initialize it and then BUG if they don't match, which is a bit
silly.
This patch cleans up cgroup_subsys names and initialization by doing
the followings.
* cgroup_subsys_id enums are now postfixed with _cgrp_id, and each
cgroup_subsys with _cgrp_subsys.
* With the above, renaming subsys identifiers to match the userland
visible names doesn't cause any naming conflicts. All non-matching
identifiers are renamed to match the official names.
cpu_cgroup -> cpu
mem_cgroup -> memory
perf -> perf_event
* controllers no longer need to initialize ->subsys_id and ->name.
They're generated in cgroup core and set automatically during boot.
* Redundant cgroup_subsys declarations removed.
* While updating BUG_ON()s in cgroup_init_early(), convert them to
WARN()s. BUGging that early during boot is stupid - the kernel
can't print anything, even through serial console and the trap
handler doesn't even link stack frame properly for back-tracing.
This patch doesn't introduce any behavior changes.
v2: Rebased on top of fe1217c4f3f7 ("net: net_cls: move cgroupfs
classid handling into core").
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: "David S. Miller" <davem@davemloft.net>
Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Ingo Molnar <mingo@redhat.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Thomas Graf <tgraf@suug.ch>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index ccb16b4..fe3f725 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -120,10 +120,18 @@
static struct workqueue_struct *cgroup_pidlist_destroy_wq;
/* generate an array of cgroup subsystem pointers */
-#define SUBSYS(_x) [_x ## _subsys_id] = &_x ## _subsys,
+#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
static struct cgroup_subsys *cgroup_subsys[] = {
#include <linux/cgroup_subsys.h>
};
+#undef SUBSYS
+
+/* array of cgroup subsystem names */
+#define SUBSYS(_x) [_x ## _cgrp_id] = #_x,
+static const char *cgroup_subsys_name[] = {
+#include <linux/cgroup_subsys.h>
+};
+#undef SUBSYS
/*
* The dummy hierarchy, reserved for the subsystems that are otherwise
@@ -1076,7 +1084,7 @@
BUG_ON(!mutex_is_locked(&cgroup_mutex));
#ifdef CONFIG_CPUSETS
- mask = ~(1UL << cpuset_subsys_id);
+ mask = ~(1UL << cpuset_cgrp_id);
#endif
memset(opts, 0, sizeof(*opts));
@@ -4528,15 +4536,15 @@
list_add(&init_cgrp_cset_link.cgrp_link, &init_css_set.cgrp_links);
for_each_subsys(ss, i) {
- BUG_ON(!ss->name);
- BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN);
- BUG_ON(!ss->css_alloc);
- BUG_ON(!ss->css_free);
- if (ss->subsys_id != i) {
- printk(KERN_ERR "cgroup: Subsys %s id == %d\n",
- ss->name, ss->subsys_id);
- BUG();
- }
+ WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->subsys_id,
+ "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p name:id=%d:%s\n",
+ i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free,
+ ss->subsys_id, ss->name);
+ WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN,
+ "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]);
+
+ ss->subsys_id = i;
+ ss->name = cgroup_subsys_name[i];
if (ss->early_init)
cgroup_init_subsys(ss);
@@ -5167,11 +5175,9 @@
{ } /* terminate */
};
-struct cgroup_subsys debug_subsys = {
- .name = "debug",
+struct cgroup_subsys debug_cgrp_subsys = {
.css_alloc = debug_css_alloc,
.css_free = debug_css_free,
- .subsys_id = debug_subsys_id,
.base_cftypes = debug_files,
};
#endif /* CONFIG_CGROUP_DEBUG */
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 6c3154e..98ea26a9 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -52,7 +52,7 @@
static inline struct freezer *task_freezer(struct task_struct *task)
{
- return css_freezer(task_css(task, freezer_subsys_id));
+ return css_freezer(task_css(task, freezer_cgrp_id));
}
static struct freezer *parent_freezer(struct freezer *freezer)
@@ -84,8 +84,6 @@
return "THAWED";
};
-struct cgroup_subsys freezer_subsys;
-
static struct cgroup_subsys_state *
freezer_css_alloc(struct cgroup_subsys_state *parent_css)
{
@@ -473,13 +471,11 @@
{ } /* terminate */
};
-struct cgroup_subsys freezer_subsys = {
- .name = "freezer",
+struct cgroup_subsys freezer_cgrp_subsys = {
.css_alloc = freezer_css_alloc,
.css_online = freezer_css_online,
.css_offline = freezer_css_offline,
.css_free = freezer_css_free,
- .subsys_id = freezer_subsys_id,
.attach = freezer_attach,
.fork = freezer_fork,
.base_cftypes = files,
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 4410ac6..2d018c7 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -119,7 +119,7 @@
/* Retrieve the cpuset for a task */
static inline struct cpuset *task_cs(struct task_struct *task)
{
- return css_cs(task_css(task, cpuset_subsys_id));
+ return css_cs(task_css(task, cpuset_cgrp_id));
}
static inline struct cpuset *parent_cs(struct cpuset *cs)
@@ -1521,7 +1521,7 @@
struct task_struct *task;
struct task_struct *leader = cgroup_taskset_first(tset);
struct cgroup_subsys_state *oldcss = cgroup_taskset_cur_css(tset,
- cpuset_subsys_id);
+ cpuset_cgrp_id);
struct cpuset *cs = css_cs(css);
struct cpuset *oldcs = css_cs(oldcss);
struct cpuset *cpus_cs = effective_cpumask_cpuset(cs);
@@ -2024,8 +2024,7 @@
kfree(cs);
}
-struct cgroup_subsys cpuset_subsys = {
- .name = "cpuset",
+struct cgroup_subsys cpuset_cgrp_subsys = {
.css_alloc = cpuset_css_alloc,
.css_online = cpuset_css_online,
.css_offline = cpuset_css_offline,
@@ -2033,7 +2032,6 @@
.can_attach = cpuset_can_attach,
.cancel_attach = cpuset_cancel_attach,
.attach = cpuset_attach,
- .subsys_id = cpuset_subsys_id,
.base_cftypes = files,
.early_init = 1,
};
@@ -2699,7 +2697,7 @@
goto out_free;
rcu_read_lock();
- css = task_css(tsk, cpuset_subsys_id);
+ css = task_css(tsk, cpuset_cgrp_id);
retval = cgroup_path(css->cgroup, buf, PAGE_SIZE);
rcu_read_unlock();
if (retval < 0)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 56003c6..6490373 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -342,7 +342,7 @@
static inline struct perf_cgroup *
perf_cgroup_from_task(struct task_struct *task)
{
- return container_of(task_css(task, perf_subsys_id),
+ return container_of(task_css(task, perf_event_cgrp_id),
struct perf_cgroup, css);
}
@@ -595,7 +595,7 @@
rcu_read_lock();
- css = css_from_dir(f.file->f_dentry, &perf_subsys);
+ css = css_from_dir(f.file->f_dentry, &perf_event_cgrp_subsys);
if (IS_ERR(css)) {
ret = PTR_ERR(css);
goto out;
@@ -8055,9 +8055,7 @@
task_function_call(task, __perf_cgroup_move, task);
}
-struct cgroup_subsys perf_subsys = {
- .name = "perf_event",
- .subsys_id = perf_subsys_id,
+struct cgroup_subsys perf_event_cgrp_subsys = {
.css_alloc = perf_cgroup_css_alloc,
.css_free = perf_cgroup_css_free,
.exit = perf_cgroup_exit,
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b46131e..d4cfc55 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7176,7 +7176,7 @@
if (unlikely(running))
tsk->sched_class->put_prev_task(rq, tsk);
- tg = container_of(task_css_check(tsk, cpu_cgroup_subsys_id,
+ tg = container_of(task_css_check(tsk, cpu_cgrp_id,
lockdep_is_held(&tsk->sighand->siglock)),
struct task_group, css);
tg = autogroup_task_group(tsk, tg);
@@ -7957,8 +7957,7 @@
{ } /* terminate */
};
-struct cgroup_subsys cpu_cgroup_subsys = {
- .name = "cpu",
+struct cgroup_subsys cpu_cgrp_subsys = {
.css_alloc = cpu_cgroup_css_alloc,
.css_free = cpu_cgroup_css_free,
.css_online = cpu_cgroup_css_online,
@@ -7966,7 +7965,6 @@
.can_attach = cpu_cgroup_can_attach,
.attach = cpu_cgroup_attach,
.exit = cpu_cgroup_exit,
- .subsys_id = cpu_cgroup_subsys_id,
.base_cftypes = cpu_files,
.early_init = 1,
};
diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c
index 622e081..c143ee3 100644
--- a/kernel/sched/cpuacct.c
+++ b/kernel/sched/cpuacct.c
@@ -41,7 +41,7 @@
/* return cpu accounting group to which this task belongs */
static inline struct cpuacct *task_ca(struct task_struct *tsk)
{
- return css_ca(task_css(tsk, cpuacct_subsys_id));
+ return css_ca(task_css(tsk, cpuacct_cgrp_id));
}
static inline struct cpuacct *parent_ca(struct cpuacct *ca)
@@ -275,11 +275,9 @@
rcu_read_unlock();
}
-struct cgroup_subsys cpuacct_subsys = {
- .name = "cpuacct",
+struct cgroup_subsys cpuacct_cgrp_subsys = {
.css_alloc = cpuacct_css_alloc,
.css_free = cpuacct_css_free,
- .subsys_id = cpuacct_subsys_id,
.base_cftypes = files,
.early_init = 1,
};