Re: [PATCH 0/7] libtracfes: Add tracefs_function_filter()

[Steven Rostedt <rostedt@goodmis.org>]

On Wed, 24 Mar 2021 15:43:28 +0530
Sameeruddin Shaik <sameeruddin.shaik8@gmail.com> wrote:

> >  - We can have a tracefs_read_function_filter() that returns an array of
> >    strings which ends with a NULL pointer (and needs to be freed with
> >    tracefs_list_free(), and have this:
> >
> >    save_filters = tracefs_read_function_filter(instance);  
> 
> are we going to use the tracefs_read_function_filter() function to
> read the set_ftrace_file for getting written filters?

Yes, why not?

But it would not return probes, only filters.

That is, the set_ftrace_filter also shows probes, and they are different.
But the tracefs_read_function_filter() should not return them. For them, we
should have a tracefs_read_function_probes() API.

-- Steve


> >
> >    ret = tracefs_function_filter(instance, filters, NULL, true, &errs);
> >    if (ret > 0 && errs) {
> >         /* Modified but failed */
> >         int i, j;
> >         for (i = 0; filters[i]; i++)
> >                 ;
> >         for (j = 0; errs[i]; j++)
> >                 ;
> >         if (i == j)
> >                 /* all filters failed! Put back the original */
> >                 tracefs_function_filter(instance, save_filters, NULL, false, NULL);
> >    }