Re: [PATCH] tracing: Have trace_marker break up by lines by size of trace_seq

[Google]

On Tue, 12 Dec 2023 19:04:22 -0500
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
> 
> If a trace_marker write is bigger than what trace_seq can hold, then it
> will print "LINE TOO BIG" message and not what was written.
> 
> Instead, if check if the write is bigger than the trace_seq and break it

Instead, check if ... ?

> up by that size.
> 
> Ideally, we could make the trace_seq dynamic that could hold this. But
> that's for another time.

I think this is OK, but if possible it is better to be merged with the
"LINE TOO BIG" patch (by updating the version).

Reviewed-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>

Thank you,

> 
> Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
> ---
>  kernel/trace/trace.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 893e749713d3..2a21bc840fe7 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -7298,6 +7298,11 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
>  	if (cnt < FAULTED_SIZE)
>  		size += FAULTED_SIZE - cnt;
>  
> +	if (size > TRACE_SEQ_BUFFER_SIZE) {
> +		cnt -= size - TRACE_SEQ_BUFFER_SIZE;
> +		goto again;
> +	}
> +
>  	buffer = tr->array_buffer.buffer;
>  	event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
>  					    tracing_gen_ctx());
> -- 
> 2.42.0
> 


-- 
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>