diff options
| author | Steven Rostedt (Google) <rostedt@goodmis.org> | 2023-01-04 16:14:12 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-02-01 08:34:37 +0100 |
| commit | 198c83963f6335ca6d690cff067679560f2a3a22 (patch) | |
| tree | b95036d65fb0f7504a8e88b6b0f4a6aad11d6e3f | |
| parent | e5ae9b5a652fa87e53076282c5855dda860fc5bd (diff) | |
| download | linux-198c83963f6335ca6d690cff067679560f2a3a22.tar.gz | |
tracing: Make sure trace_printk() can output as soon as it can be used
commit 3bb06eb6e9acf7c4a3e1b5bc87aed398ff8e2253 upstream.
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.
Link: https://lkml.kernel.org/r/20230104161412.019f6c55@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: e725c731e3bb1 ("tracing: Split tracing initialization into two for early initialization")
Reported-by: "Joel Fernandes (Google)" <joel@joelfernandes.org>
Tested-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/trace/trace.c | 2 | ||||
| -rw-r--r-- | kernel/trace/trace.h | 1 | ||||
| -rw-r--r-- | 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 3076af8dbf32..546e84ae9993 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -10291,6 +10291,8 @@ 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 5581754d9762..9e931f51328a 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1490,6 +1490,7 @@ 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); |