tracing: Enable creating new instance early boot

Enable creating new trace_array instance in early boot stage.
If the instances directory is not created, postpone it until
the tracefs is initialized.

Link: https://lkml.kernel.org/r/159974154763.478751.6289753509587233103.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c35fcd2..6211a13 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -8636,6 +8636,24 @@ struct trace_array *trace_array_find_get(const char *instance)
        return tr;
 }
 
+static int trace_array_create_dir(struct trace_array *tr)
+{
+       int ret;
+
+       tr->dir = tracefs_create_dir(tr->name, trace_instance_dir);
+       if (!tr->dir)
+               return -EINVAL;
+
+       ret = event_trace_add_tracer(tr->dir, tr);
+       if (ret)
+               tracefs_remove(tr->dir);
+
+       init_tracer_tracefs(tr, tr->dir);
+       __update_tracer_options(tr);
+
+       return ret;
+}
+
 static struct trace_array *trace_array_create(const char *name)
 {
        struct trace_array *tr;
@@ -8671,30 +8689,27 @@ static struct trace_array *trace_array_create(const char *name)
        if (allocate_trace_buffers(tr, trace_buf_size) < 0)
                goto out_free_tr;
 
-       tr->dir = tracefs_create_dir(name, trace_instance_dir);
-       if (!tr->dir)
-               goto out_free_tr;
-
-       ret = event_trace_add_tracer(tr->dir, tr);
-       if (ret) {
-               tracefs_remove(tr->dir);
+       if (ftrace_allocate_ftrace_ops(tr) < 0)
                goto out_free_tr;
-       }
 
        ftrace_init_trace_array(tr);
 
-       init_tracer_tracefs(tr, tr->dir);
        init_trace_flags_index(tr);
-       __update_tracer_options(tr);
+
+       if (trace_instance_dir) {
+               ret = trace_array_create_dir(tr);
+               if (ret)
+                       goto out_free_tr;
+       }
 
        list_add(&tr->list, &ftrace_trace_arrays);
 
        tr->ref++;
 
-
        return tr;
 
  out_free_tr:
+       ftrace_free_ftrace_ops(tr);
        free_trace_buffers(tr);
        free_cpumask_var(tr->tracing_cpumask);
        kfree(tr->name);
@@ -8852,11 +8867,27 @@ static int instance_rmdir(const char *name)
 
 static __init void create_trace_instances(struct dentry *d_tracer)
 {
+       struct trace_array *tr;
+
        trace_instance_dir = tracefs_create_instance_dir("instances", d_tracer,
                                                         instance_mkdir,
                                                         instance_rmdir);
        if (MEM_FAIL(!trace_instance_dir, "Failed to create instances directory\n"))
                return;
+
+       mutex_lock(&event_mutex);
+       mutex_lock(&trace_types_lock);
+
+       list_for_each_entry(tr, &ftrace_trace_arrays, list) {
+               if (!tr->name)
+                       continue;
+               if (MEM_FAIL(trace_array_create_dir(tr) < 0,
+                            "Failed to create instance directory\n"))
+                       break;
+       }
+
+       mutex_unlock(&trace_types_lock);
+       mutex_unlock(&event_mutex);
 }
 
 static void

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 0d3a405..5254341 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1125,6 +1125,8 @@ extern int ftrace_is_dead(void);
 int ftrace_create_function_files(struct trace_array *tr,
                                 struct dentry *parent);
 void ftrace_destroy_function_files(struct trace_array *tr);
+int ftrace_allocate_ftrace_ops(struct trace_array *tr);
+void ftrace_free_ftrace_ops(struct trace_array *tr);
 void ftrace_init_global_array_ops(struct trace_array *tr);
 void ftrace_init_array_ops(struct trace_array *tr, ftrace_func_t func);
 void ftrace_reset_array_ops(struct trace_array *tr);
@@ -1146,6 +1148,11 @@ ftrace_create_function_files(struct trace_array *tr,
 {
        return 0;
 }
+static inline int ftrace_allocate_ftrace_ops(struct trace_array *tr)
+{
+       return 0;
+}
+static inline void ftrace_free_ftrace_ops(struct trace_array *tr) { }
 static inline void ftrace_destroy_function_files(struct trace_array *tr) { }
 static inline __init void
 ftrace_init_global_array_ops(struct trace_array *tr) { }

diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index dd4dff7..2c2126e 100644 (file)
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -34,10 +34,14 @@ enum {
        TRACE_FUNC_OPT_STACK    = 0x1,
 };
 
-static int allocate_ftrace_ops(struct trace_array *tr)
+int ftrace_allocate_ftrace_ops(struct trace_array *tr)
 {
        struct ftrace_ops *ops;
 
+       /* The top level array uses the "global_ops" */
+       if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
+               return 0;
+
        ops = kzalloc(sizeof(*ops), GFP_KERNEL);
        if (!ops)
                return -ENOMEM;
@@ -48,15 +52,19 @@ static int allocate_ftrace_ops(struct trace_array *tr)
 
        tr->ops = ops;
        ops->private = tr;
+
        return 0;
 }
 
+void ftrace_free_ftrace_ops(struct trace_array *tr)
+{
+       kfree(tr->ops);
+       tr->ops = NULL;
+}
 
 int ftrace_create_function_files(struct trace_array *tr,
                                 struct dentry *parent)
 {
-       int ret;
-
        /*
         * The top level array uses the "global_ops", and the files are
         * created on boot up.
@@ -64,9 +72,8 @@ int ftrace_create_function_files(struct trace_array *tr,
        if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
                return 0;
 
-       ret = allocate_ftrace_ops(tr);
-       if (ret)
-               return ret;
+       if (!tr->ops)
+               return -EINVAL;
 
        ftrace_create_filter_files(tr->ops, parent);
 
@@ -76,8 +83,7 @@ int ftrace_create_function_files(struct trace_array *tr,
 void ftrace_destroy_function_files(struct trace_array *tr)
 {
        ftrace_destroy_filter_files(tr->ops);
-       kfree(tr->ops);
-       tr->ops = NULL;
+       ftrace_free_ftrace_ops(tr);
 }
 
 static int function_trace_init(struct trace_array *tr)