Re: [PATCH 1/2] trace-cmd: Add new tracefs API tracefs_instances_walk()

[Steven Rostedt <rostedt@goodmis.org>]

On Fri, 17 Jul 2020 11:03:25 +0300
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> The logic for finding all configured ftrace instances is encapuslated in
> the new tracefs_instances_walk() API. A user specified callback is
> called for each ftrace instance in the system, excpet for the top level
> one.
> The implementation of "trace-cmd stat" is modified to use the new API.
> 
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> ---
>  include/tracefs/tracefs.h           |  1 +
>  lib/tracefs/include/tracefs-local.h |  1 +
>  lib/tracefs/tracefs-events.c        | 14 ++++----
>  lib/tracefs/tracefs-instance.c      | 52 +++++++++++++++++++++++++++++
>  tracecmd/trace-stat.c               | 52 ++++++++---------------------
>  5 files changed, 74 insertions(+), 46 deletions(-)
> 
> diff --git a/include/tracefs/tracefs.h b/include/tracefs/tracefs.h
> index 8ee7ba6e..0dd8046f 100644
> --- a/include/tracefs/tracefs.h
> +++ b/include/tracefs/tracefs.h
> @@ -32,6 +32,7 @@ int tracefs_instance_file_write(struct tracefs_instance *instance,
>  				const char *file, const char *str);
>  char *tracefs_instance_file_read(struct tracefs_instance *instance,
>  				 char *file, int *psize);
> +int tracefs_instances_walk(int (*callback)(const char *, void *), void *context);

Perhaps a better name would be: tracefs_instance_iterate()?

I usually consider a "walk" as going through a tree, not a list. If
this was a directory tree, then "walk" would be more appropriate.

An "iterator" is something that walks through a list and triggers a
callback, like this does.

But other than that, the patch looks good.

-- Steve


>  
>  bool tracefs_file_exists(struct tracefs_instance *instance, char *name);
>  bool tracefs_dir_exists(struct tracefs_instance *instance, char *name);
> diff --git a/lib/tracefs/include/tracefs-local.h b/lib/tracefs/include/tracefs-local.h
> index fe327a0f..08b67fa9 100644
> --- a/lib/tracefs/include/tracefs-local.h
>