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tracing: Fix ftrace_boot_snapshot command line logic

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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.

Link: https://lkml.kernel.org/r/20230405022341.895334039@goodmis.org

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ross Zwisler <zwisler@google.com>
Fixes: 9c1c251d67 ("tracing: Allow boot instances to have snapshot buffers")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Google) 2023-04-04 22:21:15 -04:00
parent 9d52727f80
commit e94891641c
1 changed files with 7 additions and 6 deletions
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13
kernel/trace/trace.c
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@ -10393,19 +10393,20 @@ out:
void __init ftrace_boot_snapshot(void)
{
#ifdef CONFIG_TRACER_MAX_TRACE
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");
}
#endif
}
void __init early_trace_init(void)