Re: [PATCH v2] tracing: Record trace_clock and recover when reboot

[Steven Rostedt]

On Thu, 17 Apr 2025 14:17:29 +0900
"Masami Hiramatsu (Google)" <mhira...@kernel.org> wrote:

> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -6004,6 +6004,7 @@ struct trace_mod_entry {
>  };
>  
>  struct trace_scratch {
> +     char                    clock[TRACE_CLOCK_NAME_MAX];
>       unsigned long           text_addr;
>       unsigned long           nr_entries;
>       struct trace_mod_entry  entries[];
> @@ -6114,6 +6115,8 @@ static void update_last_data(struct trace_array *tr)
>       if (tr->scratch) {
>               struct trace_scratch *tscratch = tr->scratch;
>  
> +             strscpy(tscratch->clock, trace_clocks[tr->clock_id].name,

Why copy the name and not the clock_id?

The clock ids should not change between kernels.

-- Steve

> +                     TRACE_CLOCK_NAME_MAX);
>               memset(tscratch->entries, 0,
>                      flex_array_size(tscratch, entries, 
> tscratch->nr_entries));
>               tscratch->nr_entries = 0;