From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
The kernel command line ftrace_boot_snapshot by itself is supposed to
trigger a snapshot at the end of boot up of the main top level trace
buffer. A ftrace_boot_snapshot=foo will do the same for an instance called
foo that was created by trace_instance=foo,...
The logic was broken where if ftrace_boot_snapshot was by itself, it would
trigger a snapshot for all instances that had tracing enabled, regardless
if it asked for a snapshot or not.
When a snapshot is requested for a buffer, the buffer's
tr->allocated_snapshot is set to true. Use that to know if a trace buffer
wants a snapshot at boot up or not.
Since the top level buffer is part of the ftrace_trace_arrays list,
there's no reason to treat it differently than the other buffers. Just
iterate the list if ftrace_boot_snapshot was specified.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 9c1c251d670bc ("tracing: Allow boot instances to have snapshot buffers")
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
kernel/trace/trace.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ed1d1093f5e9..8ae51f1dea8e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -10395,16 +10395,15 @@ void __init ftrace_boot_snapshot(void)
{
struct trace_array *tr;
- if (snapshot_at_boot) {
- tracing_snapshot();
- internal_trace_puts("** Boot snapshot taken **\n");
- }
+ if (!snapshot_at_boot)
+ return;
list_for_each_entry(tr, &ftrace_trace_arrays, list) {
- if (tr == &global_trace)
+ if (!tr->allocated_snapshot)
continue;
- trace_array_puts(tr, "** Boot snapshot taken **\n");
+
tracing_snapshot_instance(tr);
+ trace_array_puts(tr, "** Boot snapshot taken **\n");
}
}
--
2.39.2
