Re: [PATCH] perf config: Refine error message to eliminate confusion

[Ian Rogers]

On Fri, Sep 24, 2021 at 4:58 AM Like Xu <like.xu.linux@xxxxxxxxx> wrote:
>
> From: Like Xu <likexu@xxxxxxxxxxx>
>
> If there is no configuration file at first, the user can
> write any pair of "key.subkey=value" to the newly created
> configuration file, while value validation against a valid
> configurable key is *deferred* until the next execution or
> the implied execution of "perf config ... ".
>
> For example:
>
>  $ rm ~/.perfconfig
>  $ perf config call-graph.dump-size=65529
>  $ cat ~/.perfconfig
>  # this file is auto-generated.
>  [call-graph]
>         dump-size = 65529
>  $ perf config call-graph.dump-size=2048
>  callchain: Incorrect stack dump size (max 65528): 65529
>  Error: wrong config key-value pair call-graph.dump-size=65529
>
> The user might expect that the second value 2048 is valid
> and can be updated to the configuration file, but the error
> message is very confusing because the first value 65529 is
> not reported as an error during the last configuration.
>
> It is recommended not to change the current behavior of
> delayed validation (as more effort is needed), but to refine
> the original error message to *clearly indicate* that the
> cause of the error is the configuration file.
>
> Signed-off-by: Like Xu <likexu@xxxxxxxxxxx>

Acked-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

> ---
>  tools/perf/util/config.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/config.c b/tools/perf/util/config.c
> index 4fb5e90d7a57..60ce5908c664 100644
> --- a/tools/perf/util/config.c
> +++ b/tools/perf/util/config.c
> @@ -801,7 +801,7 @@ int perf_config_set(struct perf_config_set *set,
>                                   section->name, item->name);
>                         ret = fn(key, value, data);
>                         if (ret < 0) {
> -                               pr_err("Error: wrong config key-value pair %s=%s\n",
> +                               pr_err("Error in the given config file: wrong config key-value pair %s=%s\n",
>                                        key, value);
>                                 /*
>                                  * Can't be just a 'break', as perf_config_set__for_each_entry()
> --
> 2.32.0
>