perf hists browser: Remove leftover from row returned from refresh

Commit-ID:  94e87a8bd529121ea90219164c65c36ea1d19e56
Gitweb:     https://git.kernel.org/tip/94e87a8bd529121ea90219164c65c36ea1d19e56
Author:     Arnaldo Carvalho de Melo <[email protected]>
AuthorDate: Fri, 6 Apr 2018 12:11:11 -0300
Committer:  Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Fri, 6 Apr 2018 12:23:25 -0300

perf hists browser: Remove leftover from row returned from refresh

The per-browser screen refresh routine (ui_browser->refresh()) should return the first row that should be cleaned after the rows just printed, in case not all rows available on the screen gets filled.

When moving the extra title lines logic from the hists browser to the generic ui_browser class, one piece of that logic remained in the hists browser and then when going back from the annotate browser to the hists browser in a case where fewer lines were displayed in the hists browser, for instance when filtering the entries per substring, one line of the annotate browser would remain on the screen, fix that.

Example of the screen artifact:

================================================================================
Samples: 73K of event 'cycles:ppp', 4000 Hz, Event count (approx.): 45172901394

Overhead  Shared O  Symbol
   0.30%  [kernel]  [k] __indirect_thunk_start
   0.09%  [kernel]  [k] __x86_indirect_thunk_r10

│ lfence
================================================================================

Here from 'perf top' the view was zoomed with '/thunk' to functions having that substring, then the first was annotated and from the annotate browser ESC was pressed, then the first lines were overwritten, but the 'lfence' line remained due to the off by one bug fixed in this cset.

---
 tools/perf/ui/browsers/hists.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

index de17e59d9952..0eec06c105c6 100644
@@ -1744,17 +1744,11 @@ static void ui_browser__hists_init_top(struct ui_browser *browser)
 static unsigned int hist_browser__refresh(struct ui_browser *browser)
 {
 	unsigned row = 0;
-	u16 header_offset = 0;
 	struct rb_node *nd;
 	struct hist_browser *hb = container_of(browser, struct hist_browser, b);
-	struct hists *hists = hb->hists;
-
-	if (hb->show_headers) {
-		struct perf_hpp_list *hpp_list = hists->hpp_list;
 
+	if (hb->show_headers)
 		hist_browser__show_headers(hb);
-		header_offset = hpp_list->nr_header_lines;
-	}
 
 	ui_browser__hists_init_top(browser);
 	hb->he_selection = NULL;

@@ -1792,7 +1786,7 @@ static unsigned int hist_browser__refresh(struct ui_browser *browser)
 			break;
 	}
 
-	return row + header_offset;
+	return row;
 }
 
 static struct rb_node *hists__filter_entries(struct rb_node *nd,