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authorLi Zefan <lizefan@huawei.com>2013-03-05 06:57:03 +0400
committerTejun Heo <tj@kernel.org>2013-03-05 21:33:25 +0400
commit7d8e0bf56a66bab08d2f316dd87e56c08cecb899 (patch)
treebe35c2daec953f0c98241c16311879dd45bc4859 /include/linux/cgroup.h
parentf50daa704f36a6544a902c52b6cf37b0493dfc5d (diff)
downloadlinux-7d8e0bf56a66bab08d2f316dd87e56c08cecb899.tar.xz
cgroup: avoid accessing modular cgroup subsys structure without locking
subsys[i] is set to NULL in cgroup_unload_subsys() at modular unload, and that's protected by cgroup_mutex, and then the memory *subsys[i] resides will be freed. So this is unsafe without any locking: if (!ss || ss->module) ... v2: - add a comment for enum cgroup_subsys_id - simplify the comment in cgroup_exit() Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'include/linux/cgroup.h')
-rw-r--r--include/linux/cgroup.h17
1 files changed, 14 insertions, 3 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 75c6ec1ba1ba..5f76829dd75e 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -44,14 +44,25 @@ extern void cgroup_unload_subsys(struct cgroup_subsys *ss);
extern const struct file_operations proc_cgroup_operations;
-/* Define the enumeration of all builtin cgroup subsystems */
+/*
+ * Define the enumeration of all cgroup subsystems.
+ *
+ * We define ids for builtin subsystems and then modular ones.
+ */
#define SUBSYS(_x) _x ## _subsys_id,
-#define IS_SUBSYS_ENABLED(option) IS_ENABLED(option)
enum cgroup_subsys_id {
+#define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option)
+#include <linux/cgroup_subsys.h>
+#undef IS_SUBSYS_ENABLED
+ CGROUP_BUILTIN_SUBSYS_COUNT,
+
+ __CGROUP_SUBSYS_TEMP_PLACEHOLDER = CGROUP_BUILTIN_SUBSYS_COUNT - 1,
+
+#define IS_SUBSYS_ENABLED(option) IS_MODULE(option)
#include <linux/cgroup_subsys.h>
+#undef IS_SUBSYS_ENABLED
CGROUP_SUBSYS_COUNT,
};
-#undef IS_SUBSYS_ENABLED
#undef SUBSYS
/* Per-subsystem/per-cgroup state maintained by the system. */