From 720dee53ad8dfd528941fbbc264574601b04488a Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Fri, 25 Sep 2020 01:40:08 +0900 Subject: [PATCH] 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: 4114fbfd02f1 ("tracing: Enable creating new instance early boot") Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace.c | 3 ++- kernel/trace/trace.h | 1 + kernel/trace/trace_events.c | 30 ++++++++++++++++-------------- 3 files changed, 19 insertions(+), 15 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 6211a13b33276..3f2533adae72a 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -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); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 525434145eead..5b0e797cacdda 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -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, diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 42c0e7df6e708..851ab37058ddf 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -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; @@ -3290,7 +3288,11 @@ int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr) goto out; down_write(&trace_event_sem); - __trace_add_event_dirs(tr); + /* 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); out: -- 2.39.5