Commit 720dee53 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt (VMware)
Browse files

tracing/boot: Initialize per-instance event list in early boot 

Initialize per-instance event list in early boot time (before
initializing instance directory on tracefs). This fixes boot-time
tracing to correctly handle the boot-time per-instance settings.

Link: https://lkml.kernel.org/r/160096560826.182763.17110991546046128881.stgit@devnote2



Fixes: 4114fbfd ("tracing: Enable creating new instance early boot")
Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent fd264ce9

kernel/trace/trace.c

+2 −1
Original line number Diff line number Diff line
@@ -8700,7 +8700,8 @@ static struct trace_array *trace_array_create(const char *name) 
		ret = trace_array_create_dir(tr);

		if (ret)

			goto out_free_tr;

	}

	} else

		__trace_early_add_events(tr);



	list_add(&tr->list, &ftrace_trace_arrays);

kernel/trace/trace.h

+1 −0
Original line number Diff line number Diff line
@@ -1658,6 +1658,7 @@ extern void trace_event_enable_tgid_record(bool enable); 
extern int event_trace_init(void);

extern int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr);

extern int event_trace_del_tracer(struct trace_array *tr);

extern void __trace_early_add_events(struct trace_array *tr);



extern struct trace_event_file *__find_event_file(struct trace_array *tr,

						  const char *system,

kernel/trace/trace_events.c

+16 −14
Original line number Diff line number Diff line
@@ -3131,14 +3131,13 @@ static inline int register_event_cmds(void) { return 0; } 
#endif /* CONFIG_DYNAMIC_FTRACE */



/*

 * The top level array has already had its trace_event_file

 * descriptors created in order to allow for early events to

 * be recorded. This function is called after the tracefs has been

 * initialized, and we now have to create the files associated

 * to the events.

 * The top level array and trace arrays created by boot-time tracing

 * have already had its trace_event_file descriptors created in order

 * to allow for early events to be recorded.

 * This function is called after the tracefs has been initialized,

 * and we now have to create the files associated to the events.

 */

static __init void

__trace_early_add_event_dirs(struct trace_array *tr)

static void __trace_early_add_event_dirs(struct trace_array *tr)

{

	struct trace_event_file *file;

	int ret;
@@ -3153,13 +3152,12 @@ __trace_early_add_event_dirs(struct trace_array *tr) 
}



/*

 * For early boot up, the top trace array requires to have

 * a list of events that can be enabled. This must be done before

 * the filesystem is set up in order to allow events to be traced

 * early.

 * For early boot up, the top trace array and the trace arrays created

 * by boot-time tracing require to have a list of events that can be

 * enabled. This must be done before the filesystem is set up in order

 * to allow events to be traced early.

 */

static __init void

__trace_early_add_events(struct trace_array *tr)

void __trace_early_add_events(struct trace_array *tr)

{

	struct trace_event_call *call;

	int ret;
@@ -3290,6 +3288,10 @@ int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr) 
		goto out;



	down_write(&trace_event_sem);

	/* If tr already has the event list, it is initialized in early boot. */

	if (unlikely(!list_empty(&tr->events)))

		__trace_early_add_event_dirs(tr);

	else

		__trace_add_event_dirs(tr);

	up_write(&trace_event_sem);

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