| Message ID | 20230104161412.019f6c55@gandalf.local.home (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 3bb06eb6e9acf7c4a3e1b5bc87aed398ff8e2253 |
| Headers | show |
| Series | tracing: Make sure trace_printk() can output as soon as it can be used | expand |
On Wed, Jan 04, 2023 at 04:14:12PM -0500, Steven Rostedt wrote: > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > > Currently trace_printk() can be used as soon as early_trace_init() is > called from start_kernel(). But if a crash happens, and > "ftrace_dump_on_oops" is set on the kernel command line, all you get will > be: > > [ 0.456075] <idle>-0 0dN.2. 347519us : Unknown type 6 > [ 0.456075] <idle>-0 0dN.2. 353141us : Unknown type 6 > [ 0.456075] <idle>-0 0dN.2. 358684us : Unknown type 6 > > This is because the trace_printk() event (type 6) hasn't been registered > yet. That gets done via an early_initcall(), which may be early, but not > early enough. > > Instead of registering the trace_printk() event (and other ftrace events, > which are not trace events) via an early_initcall(), have them registered at > the same time that trace_printk() can be used. This way, if there is a > crash before early_initcall(), then the trace_printk()s will actually be > useful. > > Cc: stable@vger.kernel.org > Reported-by: "Joel Fernandes (Google)" <joel@joelfernandes.org> > Fixes: e725c731e3bb1 ("tracing: Split tracing initialization into two for early initialization") > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Tested-by: Joel Fernandes (Google) <joel@joelfernandes.org> thanks, - Joel > --- > kernel/trace/trace.c | 2 ++ > kernel/trace/trace.h | 1 + > kernel/trace/trace_output.c | 3 +-- > 3 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index d3005279165d..80de338f1277 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -10196,6 +10196,8 @@ void __init early_trace_init(void) > static_key_enable(&tracepoint_printk_key.key); > } > tracer_alloc_buffers(); > + > + init_events(); > } > > void __init trace_init(void) > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > index 900e75d96c84..11c4918ff202 100644 > --- a/kernel/trace/trace.h > +++ b/kernel/trace/trace.h > @@ -1504,6 +1504,7 @@ extern void trace_event_enable_cmd_record(bool enable); > extern void trace_event_enable_tgid_record(bool enable); > > extern int event_trace_init(void); > +extern int init_events(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); > diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c > index 67f47ea27921..5cd4fb656306 100644 > --- a/kernel/trace/trace_output.c > +++ b/kernel/trace/trace_output.c > @@ -1568,7 +1568,7 @@ static struct trace_event *events[] __initdata = { > NULL > }; > > -__init static int init_events(void) > +__init int init_events(void) > { > struct trace_event *event; > int i, ret; > @@ -1581,4 +1581,3 @@ __init static int init_events(void) > > return 0; > } > -early_initcall(init_events); > -- > 2.35.1 >
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index d3005279165d..80de338f1277 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -10196,6 +10196,8 @@ void __init early_trace_init(void) static_key_enable(&tracepoint_printk_key.key); } tracer_alloc_buffers(); + + init_events(); } void __init trace_init(void) diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 900e75d96c84..11c4918ff202 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1504,6 +1504,7 @@ extern void trace_event_enable_cmd_record(bool enable); extern void trace_event_enable_tgid_record(bool enable); extern int event_trace_init(void); +extern int init_events(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); diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c index 67f47ea27921..5cd4fb656306 100644 --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -1568,7 +1568,7 @@ static struct trace_event *events[] __initdata = { NULL }; -__init static int init_events(void) +__init int init_events(void) { struct trace_event *event; int i, ret; @@ -1581,4 +1581,3 @@ __init static int init_events(void) return 0; } -early_initcall(init_events);