perf top: Fix number of samples displayed

In recent versions of perf top, pressing the 'e' key to change the
number of displayed samples had no effect.

The number of samples was still dictated by the size of the terminal
(stdio mode). That was quite annoying because typically only the first
dozen samples really matter.

This patch fixes this.

Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20120130105037.GA5160@quadSigned-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-top.c

@@ -88,8 +88,6 @@ void get_term_dimensions(struct winsize *ws)
 
 static void perf_top__update_print_entries(struct perf_top *top)
 {
-	top->print_entries = top->winsize.ws_row;
-
 	if (top->print_entries > 9)
 		top->print_entries -= 9;
 }
@@ -99,6 +97,13 @@ static void perf_top__sig_winch(int sig __used, siginfo_t *info __used, void *ar
 	struct perf_top *top = arg;
 
 	get_term_dimensions(&top->winsize);
+	if (!top->print_entries
+	    || (top->print_entries+4) > top->winsize.ws_row) {
+		top->print_entries = top->winsize.ws_row;
+	} else {
+		top->print_entries += 4;
+		top->winsize.ws_row = top->print_entries;
+	}
 	perf_top__update_print_entries(top);
 }
 
@@ -452,8 +457,10 @@ static void perf_top__handle_keypress(struct perf_top *top, int c)
 				};
 				perf_top__sig_winch(SIGWINCH, NULL, top);
 				sigaction(SIGWINCH, &act, NULL);
-			} else
+			} else {
+				perf_top__sig_winch(SIGWINCH, NULL, top);
 				signal(SIGWINCH, SIG_DFL);
+			}
 			break;
 		case 'E':
 			if (top->evlist->nr_entries > 1) {