Re: [PATCH 01/12] perf tools: Separate generic code in dso__data_file_size

Arnaldo Carvalho de Melo
2019-05-13T19:48:46Z

Em Wed, May 08, 2019 at 03:19:59PM +0200, Jiri Olsa escreveu:
> Moving file specific code in dso__data_file_size function
> into separate file_size function. I'll add bpf specific
> code in following patches.

I'm applying this patch, as it just moves things around, no logic
change, but can you please clarify a question I have after looking at
this patch?

> Link: http://lkml.kernel.org/n/tip-rkcsft4a0f8sw33p67llxf0d@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> tools/perf/util/dso.c | 19 ++++++++++++-------
> 1 file changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
> index e059976d9d93..cb6199c1390a 100644
> --- a/tools/perf/util/dso.c
> +++ b/tools/perf/util/dso.c
> @@ -898,18 +898,12 @@ static ssize_t cached_read(struct dso *dso, struct machine *machine,
> return r;
> }
>
> -int dso__data_file_size(struct dso *dso, struct machine *machine)
> +static int file_size(struct dso *dso, struct machine *machine)
> {
> int ret = 0;
> struct stat st;
> char sbuf[STRERR_BUFSIZE];
>
> - if (dso->data.file_size)
> - return 0;
> -
> - if (dso->data.status == DSO_DATA_STATUS_ERROR)
> - return -1;
> -
> pthread_mutex_lock(&dso__data_open_lock);
>
> /*
> @@ -938,6 +932,17 @@ int dso__data_file_size(struct dso *dso, struct machine *machine)
> return ret;
> }
>
> +int dso__data_file_size(struct dso *dso, struct machine *machine)
> +{
> + if (dso->data.file_size)
> + return 0;
> +
> + if (dso->data.status == DSO_DATA_STATUS_ERROR)
> + return -1;
> +
> + return file_size(dso, machine);
> +}

So the name of the function suggests we want to know the
"data_file_size" of a dso, then the logic in it returns _zero_ if a
member named "dso->data.file_size" is _not_ zero, can you please
clarify?

I was expecting something like:

if (dso->data.file_size)
return dso->data.file_size;

I.e. if we had already read it, return the cached value, otherwise go
and call some other function to get that info somehow.

- Arnaldo

> +
> /**
> * dso__data_size - Return dso data size
> * @dso: dso object
> --
> 2.20.1

--

- Arnaldo