Re: [PATCH 2/2] perf hists browser: Reset selection when refresh

[Namhyung Kim <namhyung@kernel.org>]

On Wed, Dec 02, 2015 at 12:51:33PM +0000, Wang Nan wrote:
> With following steps:
> 
>  Step 1: perf report
> 
>  Step 2: Use UP/DOWN to select an entry, don't press 'ENTER'
> 
>  Step 3: Use '/' to filter symbols, use a filter which returns
>          empty result
> 
>  Step 4: Press 'ENTER'
> 
> We see that, even if we have filter all symbols (and the main interface
> is empty), pressing 'ENTER' still select one symbol. This behavior
> surprise user. This patch resets browser->selection in
> hist_browser__refresh() and let it choose default selection. In this
> case browser->selection keeps NULL so user won't see annotation item
> in menu.
> 
> Signed-off-by: Wang Nan <wangnan0@huawei.com>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> ---
> 
> Note that if this patch is applied before 1/2 then the steps listed in
> commit message in 1/2 won't trigger segfault. However I believe patch 1/1
> is still required.
> 
> ---
>  tools/perf/ui/browsers/hists.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
> index 9458da8..523a9ef 100644
> --- a/tools/perf/ui/browsers/hists.c
> +++ b/tools/perf/ui/browsers/hists.c
> @@ -1192,6 +1192,7 @@ static unsigned int hist_browser__refresh(struct ui_browser *browser)
>  	}
>  
>  	ui_browser__hists_init_top(browser);
> +	hb->selection = NULL;

This code assumes that hb->selection is not NULL if hb->he_selection
is not NULL.  So I think that the right (and simple) fix is to reset
hb->he_selection rather than hb->selection (or both).  It'll make the
change below unnecessary IMHO.

Thanks,
Namhyung


>  
>  	for (nd = browser->top; nd; nd = rb_next(nd)) {
>  		struct hist_entry *h = rb_entry(nd, struct hist_entry, rb_node);
> @@ -2102,7 +2103,7 @@ static int perf_evsel__hists_browse(struct perf_evsel *evsel, int nr_events,
>  
>  		if (browser->he_selection != NULL) {
>  			thread = hist_browser__selected_thread(browser);
> -			map = browser->selection->map;
> +			map = browser->selection ? browser->selection->map : NULL;
>  			socked_id = browser->he_selection->socket;
>  		}
>  		switch (key) {
> @@ -2321,7 +2322,8 @@ skip_annotation:
>  			nr_options += add_script_opt(browser,
>  						     &actions[nr_options],
>  						     &options[nr_options],
> -						     NULL, browser->selection->sym);
> +						     NULL, browser->selection ?
> +						     		browser->selection->sym : NULL);
>  		}
>  		nr_options += add_script_opt(browser, &actions[nr_options],
>  					     &options[nr_options], NULL, NULL);
> -- 
> 1.8.3.4
>