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

[Bo Yan]

Steven,

Thanks for review. I have posted the following update

https://lkml.org/lkml/2017/9/18/715

Bo

On 09/18/2017 07:38 AM, Steven Rostedt wrote:
> 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) {