Re: [PATCH] tracing: erase irqsoff trace with empty write

From: Steven Rostedt
Date: Mon Sep 18 2017 - 10:38:47 EST


On Mon, 11 Sep 2017 11:16:35 -0700
Bo Yan <byan@xxxxxxxxxx> wrote:

> One convenient way to erase trace is "echo > trace". However, this
> is currently broken if the current tracer is irqsoff tracer. This
> is because irqsoff tracer use max_buffer as the default trace
> buffer.
>
> Set the max_buffer as the one to be cleared when it's the trace
> buffer currently in use.

Hi Bo,

I have no problems with the logic of the patch. But just one nit. The
tr->trace_buffer has been called "trace_buf" elsewhere in the file. Can
you resend with using the variable name "trace_buf" instead of "tr_buf"
just to keep it consistent in the file. It's also been called 'buf' but
trace_buf would probably be more appropriate.

Thanks!

-- Steve

>
> Signed-off-by: Bo Yan <byan@xxxxxxxxxx>
> ---
> kernel/trace/trace.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 5360b7aec57a..1f91bdd9365b 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -4020,11 +4020,17 @@ static int tracing_open(struct inode *inode, struct file *file)
> /* If this file was open for write, then erase contents */
> if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
> int cpu = tracing_get_cpu(inode);
> + struct trace_buffer *tr_buf = &tr->trace_buffer;
> +
> +#ifdef CONFIG_TRACER_MAX_TRACE
> + if (tr->current_trace->print_max)
> + tr_buf = &tr->max_buffer;
> +#endif
>
> if (cpu == RING_BUFFER_ALL_CPUS)
> - tracing_reset_online_cpus(&tr->trace_buffer);
> + tracing_reset_online_cpus(tr_buf);
> else
> - tracing_reset(&tr->trace_buffer, cpu);
> + tracing_reset(tr_buf, cpu);
> }
>
> if (file->f_mode & FMODE_READ) {