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)" <mhiramat@xxxxxxxxxx> 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;