From add0c59d802e6118e51e21244c3871be35164e4b Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Tue, 9 Jul 2013 16:17:39 -0700
Subject: cgroup: remove bcache_subsys_id which got added stealthily
cafe563591 ("bcache: A block layer cache") added a new cgroup
subsystem bcache_subsys without proper review and ack. bcache_subsys
seems to use cgroup for group stats and per-group cache_mode
configuration. This is very much the type of usage that we don't want
to allow.
Fortunately, CONFIG_CGROUP_BCACHE which enables bcache_subsys is
currently commented out, so this shouldn't have any upstream users.
Let's nip in the bud. While at it, clarify in cgroup_subsys.h that no
new subsystem should be added without explicit acks from cgroup
maintainers.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: cgroups@vger.kernel.org
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-bcache@vger.kernel.org
---
include/linux/cgroup_subsys.h | 45 +++++++------------------------------------
1 file changed, 7 insertions(+), 38 deletions(-)
diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h
index 6e7ec64b69a..b613ffd402d 100644
--- a/include/linux/cgroup_subsys.h
+++ b/include/linux/cgroup_subsys.h
@@ -1,86 +1,55 @@
-/* Add subsystem definitions of the form SUBSYS(<name>) in this
- * file. Surround each one by a line of comment markers so that
- * patches don't collide
+/*
+ * List of cgroup subsystems.
+ *
+ * DO NOT ADD ANY SUBSYSTEM WITHOUT EXPLICIT ACKS FROM CGROUP MAINTAINERS.
*/
-
-/* */
-
-/* */
-
#if IS_SUBSYS_ENABLED(CONFIG_CPUSETS)
SUBSYS(cpuset)
#endif
-/* */
-
#if IS_SUBSYS_ENABLED(CONFIG_CGROUP_DEBUG)
SUBSYS(debug)
#endif
-/* */
-
#if IS_SUBSYS_ENABLED(CONFIG_CGROUP_SCHED)
SUBSYS(cpu_cgroup)
#endif
-/* */
-
#if IS_SUBSYS_ENABLED(CONFIG_CGROUP_CPUACCT)
SUBSYS(cpuacct)
#endif
-/* */
-
#if IS_SUBSYS_ENABLED(CONFIG_MEMCG)
SUBSYS(mem_cgroup)
#endif
-/* */
-
#if IS_SUBSYS_ENABLED(CONFIG_CGROUP_DEVICE)
SUBSYS(devices)
#endif
-/* */
-
#if IS_SUBSYS_ENABLED(CONFIG_CGROUP_FREEZER)
SUBSYS(freezer)
#endif
-/* */
-
#if IS_SUBSYS_ENABLED(CONFIG_NET_CLS_CGROUP)
SUBSYS(net_cls)
#endif
-/* */
-
#if IS_SUBSYS_ENABLED(CONFIG_BLK_CGROUP)
SUBSYS(blkio)
#endif
-/* */
-
#if IS_SUBSYS_ENABLED(CONFIG_CGROUP_PERF)
SUBSYS(perf)
#endif
-/* */
-
#if IS_SUBSYS_ENABLED(CONFIG_NETPRIO_CGROUP)
SUBSYS(net_prio)
#endif
-/* */
-
#if IS_SUBSYS_ENABLED(CONFIG_CGROUP_HUGETLB)
SUBSYS(hugetlb)
#endif
-
-/* */
-
-#ifdef CONFIG_CGROUP_BCACHE
-SUBSYS(bcache)
-#endif
-
-/* */
+/*
+ * DO NOT ADD ANY SUBSYSTEM WITHOUT EXPLICIT ACKS FROM CGROUP MAINTAINERS.
+ */
--
cgit v1.2.3-18-g5258
From 913ffdb54366f94eec65c656cae8c6e00e1ab1b0 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Thu, 11 Jul 2013 16:34:48 -0700
Subject: cgroup: replace task_cgroup_path_from_hierarchy() with
task_cgroup_path()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
task_cgroup_path_from_hierarchy() was added for the planned new users
and none of the currently planned users wants to know about multiple
hierarchies. This patch drops the multiple hierarchy part and makes
it always return the path in the first non-dummy hierarchy.
As unified hierarchy will always have id 1, this is guaranteed to
return the path for the unified hierarchy if mounted; otherwise, it
will return the path from the hierarchy which happens to occupy the
lowest hierarchy id, which will usually be the first hierarchy mounted
after boot.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Jan Kaluža <jkaluza@redhat.com>
---
include/linux/cgroup.h | 3 +--
kernel/cgroup.c | 31 +++++++++++++++++++------------
2 files changed, 20 insertions(+), 14 deletions(-)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index fd097ecfcd9..21cfaff7e00 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -540,8 +540,7 @@ int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor);
int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen);
-int task_cgroup_path_from_hierarchy(struct task_struct *task, int hierarchy_id,
- char *buf, size_t buflen);
+int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen);
int cgroup_task_count(const struct cgroup *cgrp);
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index e5583d10a32..afb8d53ca6c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1846,36 +1846,43 @@ out:
EXPORT_SYMBOL_GPL(cgroup_path);
/**
- * task_cgroup_path_from_hierarchy - cgroup path of a task on a hierarchy
+ * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
* @task: target task
- * @hierarchy_id: the hierarchy to look up @task's cgroup from
* @buf: the buffer to write the path into
* @buflen: the length of the buffer
*
- * Determine @task's cgroup on the hierarchy specified by @hierarchy_id and
- * copy its path into @buf. This function grabs cgroup_mutex and shouldn't
- * be used inside locks used by cgroup controller callbacks.
+ * Determine @task's cgroup on the first (the one with the lowest non-zero
+ * hierarchy_id) cgroup hierarchy and copy its path into @buf. This
+ * function grabs cgroup_mutex and shouldn't be used inside locks used by
+ * cgroup controller callbacks.
+ *
+ * Returns 0 on success, fails with -%ENAMETOOLONG if @buflen is too short.
*/
-int task_cgroup_path_from_hierarchy(struct task_struct *task, int hierarchy_id,
- char *buf, size_t buflen)
+int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
{
struct cgroupfs_root *root;
- struct cgroup *cgrp = NULL;
- int ret = -ENOENT;
+ struct cgroup *cgrp;
+ int hierarchy_id = 1, ret = 0;
+
+ if (buflen < 2)
+ return -ENAMETOOLONG;
mutex_lock(&cgroup_mutex);
- root = idr_find(&cgroup_hierarchy_idr, hierarchy_id);
+ root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id);
+
if (root) {
cgrp = task_cgroup_from_root(task, root);
ret = cgroup_path(cgrp, buf, buflen);
+ } else {
+ /* if no hierarchy exists, everyone is in "/" */
+ memcpy(buf, "/", 2);
}
mutex_unlock(&cgroup_mutex);
-
return ret;
}
-EXPORT_SYMBOL_GPL(task_cgroup_path_from_hierarchy);
+EXPORT_SYMBOL_GPL(task_cgroup_path);
/*
* Control Group taskset
--
cgit v1.2.3-18-g5258