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| author | Steven Rostedt (Google) <rostedt@goodmis.org> | 2023-01-04 16:14:12 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-02-01 08:27:23 +0100 |
| commit | b0af180514edea6c83dc9a299d9f383009c99f25 (patch) | |
| tree | cf5bd81e4df426e9b7c093841f9e2049378521ab /kernel/trace | |
| parent | 91135d72338838ce32bf6f87e788dc57703aabb6 (diff) | |
| download | linux-b0af180514edea6c83dc9a299d9f383009c99f25.tar.gz linux-b0af180514edea6c83dc9a299d9f383009c99f25.tar.bz2 linux-b0af180514edea6c83dc9a299d9f383009c99f25.zip | |
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>
Diffstat (limited to 'kernel/trace')
| -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 114d94d1e0a9..06ff4dea34d0 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -10217,6 +10217,8 @@ 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 9fc598165f3a..66b6c8395fbc 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1500,6 +1500,7 @@ 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 c2ca40e8595b..6b4d3f3abdae 100644 --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -1569,7 +1569,7 @@ 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; @@ -1587,4 +1587,3 @@ __init static int init_events(void) return 0; } -early_initcall(init_events); |