From 006cb99200a38a8e3b0cbc1be48035a08921e601 Mon Sep 17 00:00:00 2001
From: Paul Menage <menage@google.com>
Date: Thu, 18 Oct 2007 23:39:43 -0700
Subject: [PATCH] Task Control Groups: simple task cgroup debug info subsystem
This example subsystem exports debugging information as an aid to diagnosing
refcount leaks, etc, in the cgroup framework.
Signed-off-by: Paul Menage <menage@google.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/cgroup_subsys.h | 4 ++
init/Kconfig | 10 ++++
kernel/Makefile | 1 +
kernel/cgroup_debug.c | 97 +++++++++++++++++++++++++++++++++++
4 files changed, 112 insertions(+)
create mode 100644 kernel/cgroup_debug.c
diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h
index a568b8746f18..cbadc3b5dbc0 100644
--- a/include/linux/cgroup_subsys.h
+++ b/include/linux/cgroup_subsys.h
@@ -19,4 +19,8 @@ SUBSYS(cpuacct)
/* */
+#ifdef CONFIG_CGROUP_DEBUG
+SUBSYS(debug)
+#endif
+
/* */
diff --git a/init/Kconfig b/init/Kconfig
index b59a0a95a0e6..6687f805b38d 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -278,6 +278,16 @@ config CGROUPS
Say N if unsure.
+config CGROUP_DEBUG
+ bool "Example debug cgroup subsystem"
+ depends on CGROUPS
+ help
+ This option enables a simple cgroup subsystem that
+ exports useful debugging information about the cgroups
+ framework
+
+ Say N if unsure
+
config CPUSETS
bool "Cpuset support"
depends on SMP && CGROUPS
diff --git a/kernel/Makefile b/kernel/Makefile
index 48a7fae00271..a50a6debe5fc 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -37,6 +37,7 @@ obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
obj-$(CONFIG_KEXEC) += kexec.o
obj-$(CONFIG_COMPAT) += compat.o
obj-$(CONFIG_CGROUPS) += cgroup.o
+obj-$(CONFIG_CGROUP_DEBUG) += cgroup_debug.o
obj-$(CONFIG_CPUSETS) += cpuset.o
obj-$(CONFIG_CGROUP_CPUACCT) += cpu_acct.o
obj-$(CONFIG_IKCONFIG) += configs.o
diff --git a/kernel/cgroup_debug.c b/kernel/cgroup_debug.c
new file mode 100644
index 000000000000..37301e877cb0
--- /dev/null
+++ b/kernel/cgroup_debug.c
@@ -0,0 +1,97 @@
+/*
+ * kernel/ccontainer_debug.c - Example cgroup subsystem that
+ * exposes debug info
+ *
+ * Copyright (C) Google Inc, 2007
+ *
+ * Developed by Paul Menage (menage@google.com)
+ *
+ */
+
+#include <linux/cgroup.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/rcupdate.h>
+
+#include <asm/atomic.h>
+
+static struct cgroup_subsys_state *debug_create(struct cgroup_subsys *ss,
+ struct cgroup *cont)
+{
+ struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
+
+ if (!css)
+ return ERR_PTR(-ENOMEM);
+
+ return css;
+}
+
+static void debug_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
+{
+ kfree(cont->subsys[debug_subsys_id]);
+}
+
+static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft)
+{
+ return atomic_read(&cont->count);
+}
+
+static u64 taskcount_read(struct cgroup *cont, struct cftype *cft)
+{
+ u64 count;
+
+ cgroup_lock();
+ count = cgroup_task_count(cont);
+ cgroup_unlock();
+ return count;
+}
+
+static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft)
+{
+ return (u64)(long)current->cgroups;
+}
+
+static u64 current_css_set_refcount_read(struct cgroup *cont,
+ struct cftype *cft)
+{
+ u64 count;
+
+ rcu_read_lock();
+ count = atomic_read(¤t->cgroups->ref.refcount);
+ rcu_read_unlock();
+ return count;
+}
+
+static struct cftype files[] = {
+ {
+ .name = "cgroup_refcount",
+ .read_uint = cgroup_refcount_read,
+ },
+ {
+ .name = "taskcount",
+ .read_uint = taskcount_read,
+ },
+
+ {
+ .name = "current_css_set",
+ .read_uint = current_css_set_read,
+ },
+
+ {
+ .name = "current_css_set_refcount",
+ .read_uint = current_css_set_refcount_read,
+ },
+};
+
+static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont)
+{
+ return cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
+}
+
+struct cgroup_subsys debug_subsys = {
+ .name = "debug",
+ .create = debug_create,
+ .destroy = debug_destroy,
+ .populate = debug_populate,
+ .subsys_id = debug_subsys_id,
+};
--
GitLab