diff --git a/include/trace/events/cgroup.h b/include/trace/events/cgroup.h
index d74722c2ac8b..a401ff5e7847 100644
--- a/include/trace/events/cgroup.h
+++ b/include/trace/events/cgroup.h
@@ -53,24 +53,22 @@ DEFINE_EVENT(cgroup_root, cgroup_remount,
DECLARE_EVENT_CLASS(cgroup,
- TP_PROTO(struct cgroup *cgrp),
+ TP_PROTO(struct cgroup *cgrp, const char *path),
- TP_ARGS(cgrp),
+ TP_ARGS(cgrp, path),
TP_STRUCT__entry(
__field( int, root )
__field( int, id )
__field( int, level )
- __dynamic_array(char, path,
- cgroup_path(cgrp, NULL, 0) + 1)
+ __string( path, path )
),
TP_fast_assign(
__entry->root = cgrp->root->hierarchy_id;
__entry->id = cgrp->id;
__entry->level = cgrp->level;
- cgroup_path(cgrp, __get_dynamic_array(path),
- __get_dynamic_array_len(path));
+ __assign_str(path, path);
),
TP_printk("root=%d id=%d level=%d path=%s",
@@ -79,45 +77,45 @@ DECLARE_EVENT_CLASS(cgroup,
DEFINE_EVENT(cgroup, cgroup_mkdir,
- TP_PROTO(struct cgroup *cgroup),
+ TP_PROTO(struct cgroup *cgrp, const char *path),
- TP_ARGS(cgroup)
+ TP_ARGS(cgrp, path)
);
DEFINE_EVENT(cgroup, cgroup_rmdir,
- TP_PROTO(struct cgroup *cgroup),
+ TP_PROTO(struct cgroup *cgrp, const char *path),
- TP_ARGS(cgroup)
+ TP_ARGS(cgrp, path)
);
DEFINE_EVENT(cgroup, cgroup_release,
- TP_PROTO(struct cgroup *cgroup),
+ TP_PROTO(struct cgroup *cgrp, const char *path),
- TP_ARGS(cgroup)
+ TP_ARGS(cgrp, path)
);
DEFINE_EVENT(cgroup, cgroup_rename,
- TP_PROTO(struct cgroup *cgroup),
+ TP_PROTO(struct cgroup *cgrp, const char *path),
- TP_ARGS(cgroup)
+ TP_ARGS(cgrp, path)
);
DECLARE_EVENT_CLASS(cgroup_migrate,
- TP_PROTO(struct cgroup *dst_cgrp, struct task_struct *task, bool threadgroup),
+ TP_PROTO(struct cgroup *dst_cgrp, const char *path,
+ struct task_struct *task, bool threadgroup),
- TP_ARGS(dst_cgrp, task, threadgroup),
+ TP_ARGS(dst_cgrp, path, task, threadgroup),
TP_STRUCT__entry(
__field( int, dst_root )
__field( int, dst_id )
__field( int, dst_level )
- __dynamic_array(char, dst_path,
- cgroup_path(dst_cgrp, NULL, 0) + 1)
__field( int, pid )
+ __string( dst_path, path )
__string( comm, task->comm )
),
@@ -125,8 +123,7 @@ DECLARE_EVENT_CLASS(cgroup_migrate,
__entry->dst_root = dst_cgrp->root->hierarchy_id;
__entry->dst_id = dst_cgrp->id;
__entry->dst_level = dst_cgrp->level;
- cgroup_path(dst_cgrp, __get_dynamic_array(dst_path),
- __get_dynamic_array_len(dst_path));
+ __assign_str(dst_path, path);
__entry->pid = task->pid;
__assign_str(comm, task->comm);
),
@@ -138,16 +135,18 @@ DECLARE_EVENT_CLASS(cgroup_migrate,
DEFINE_EVENT(cgroup_migrate, cgroup_attach_task,
- TP_PROTO(struct cgroup *dst_cgrp, struct task_struct *task, bool threadgroup),
+ TP_PROTO(struct cgroup *dst_cgrp, const char *path,
+ struct task_struct *task, bool threadgroup),
- TP_ARGS(dst_cgrp, task, threadgroup)
+ TP_ARGS(dst_cgrp, path, task, threadgroup)
);
DEFINE_EVENT(cgroup_migrate, cgroup_transfer_tasks,
- TP_PROTO(struct cgroup *dst_cgrp, struct task_struct *task, bool threadgroup),
+ TP_PROTO(struct cgroup *dst_cgrp, const char *path,
+ struct task_struct *task, bool threadgroup),
- TP_ARGS(dst_cgrp, task, threadgroup)
+ TP_ARGS(dst_cgrp, path, task, threadgroup)
);
#endif /* _TRACE_CGROUP_H */
diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
index 77ff1cd6a252..75568fcf2180 100644
--- a/kernel/cgroup/cgroup-internal.h
+++ b/kernel/cgroup/cgroup-internal.h
@@ -8,6 +8,32 @@
#include <linux/list.h>
#include <linux/refcount.h>
+#define TRACE_CGROUP_PATH_LEN 1024
+extern spinlock_t trace_cgroup_path_lock;
+extern char trace_cgroup_path[TRACE_CGROUP_PATH_LEN];
+
+/*
+ * cgroup_path() takes a spin lock. It is good practice not to take
+ * spin locks within trace point handlers, as they are mostly hidden
+ * from normal view. As cgroup_path() can take the kernfs_rename_lock
+ * spin lock, it is best to not call that function from the trace event
+ * handler.
+ *
+ * Note: trace_cgroup_##type##_enabled() is a static branch that will only
+ * be set when the trace event is enabled.
+ */
+#define TRACE_CGROUP_PATH(type, cgrp, ...) \
+ do { \
+ if (trace_cgroup_##type##_enabled()) { \
+ spin_lock(&trace_cgroup_path_lock); \
+ cgroup_path(cgrp, trace_cgroup_path, \
+ TRACE_CGROUP_PATH_LEN); \
+ trace_cgroup_##type(cgrp, trace_cgroup_path, \
+ ##__VA_ARGS__); \
+ spin_unlock(&trace_cgroup_path_lock); \
+ } \
+ } while (0)
+
/*
* A cgroup can be associated with multiple css_sets as different tasks may
* belong to different cgroups on different hierarchies. In the other
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 8b4f0768efd6..51063e7a93c2 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -135,7 +135,7 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
if (task) {
ret = cgroup_migrate(task, false, &mgctx);
if (!ret)
- trace_cgroup_transfer_tasks(to, task, false);
+ TRACE_CGROUP_PATH(transfer_tasks, to, task, false);
put_task_struct(task);
}
} while (task && !ret);
@@ -865,7 +865,7 @@ static int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent
ret = kernfs_rename(kn, new_parent, new_name_str);
if (!ret)
- trace_cgroup_rename(cgrp);
+ TRACE_CGROUP_PATH(rename, cgrp);
mutex_unlock(&cgroup_mutex);
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 35cf3d71f8aa..aae10baf1902 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -83,6 +83,9 @@ EXPORT_SYMBOL_GPL(cgroup_mutex);
EXPORT_SYMBOL_GPL(css_set_lock);
#endif
+DEFINE_SPINLOCK(trace_cgroup_path_lock);
+char trace_cgroup_path[TRACE_CGROUP_PATH_LEN];
+
/*
* Protects cgroup_idr and css_idr so that IDs can be released without
* grabbing cgroup_mutex.
@@ -2638,7 +2641,7 @@ int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
cgroup_migrate_finish(&mgctx);
if (!ret)
- trace_cgroup_attach_task(dst_cgrp, leader, threadgroup);
+ TRACE_CGROUP_PATH(attach_task, dst_cgrp, leader, threadgroup);
return ret;
}
@@ -4636,7 +4639,7 @@ static void css_release_work_fn(struct work_struct *work)
struct cgroup *tcgrp;
/* cgroup release path */
- trace_cgroup_release(cgrp);
+ TRACE_CGROUP_PATH(release, cgrp);
if (cgroup_on_dfl(cgrp))
cgroup_rstat_flush(cgrp);
@@ -4979,7 +4982,7 @@ int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode)
if (ret)
goto out_destroy;
- trace_cgroup_mkdir(cgrp);
+ TRACE_CGROUP_PATH(mkdir, cgrp);
/* let's create and online css's */
kernfs_activate(kn);
@@ -5167,9 +5170,8 @@ int cgroup_rmdir(struct kernfs_node *kn)
return 0;
ret = cgroup_destroy_locked(cgrp);
-
if (!ret)
- trace_cgroup_rmdir(cgrp);
+ TRACE_CGROUP_PATH(rmdir, cgrp);
cgroup_kn_unlock(kn);
return ret;