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

[Wang Nan <wangnan0@huawei.com>]

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;
 
 	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