perf top: Fix TUI exit screen refresh race condition

When the following command is executed several times, a coredump file is
generated.

	$ timeout -k 9 5 perf top -e task-clock
	*******
	*******
	*******
	0.01%  [kernel]                  [k] __do_softirq
	0.01%  libpthread-2.28.so        [.] __pthread_mutex_lock
	0.01%  [kernel]                  [k] __ll_sc_atomic64_sub_return
	double free or corruption (!prev) perf top --sort comm,dso
	timeout: the monitored command dumped core

When we terminate "perf top" using sending signal method,
SLsmg_reset_smg() called. SLsmg_reset_smg() resets the SLsmg screen
management routines by freeing all memory allocated while it was active.

However SLsmg_reinit_smg() maybe be called by another thread.

SLsmg_reinit_smg() will free the same memory accessed by
SLsmg_reset_smg(), thus it results in a double free.

SLsmg_reinit_smg() is called already protected by ui__lock, so we fix
the problem by adding pthread_mutex_trylock of ui__lock when calling
SLsmg_reset_smg().
Signed-off-by: Wenyu Liu <liuwenyu7@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: wuxu.wu@huawei.com
Link: http://lore.kernel.org/lkml/a91e3943-7ddc-f5c0-a7f5-360f073c20e6@huawei.comSigned-off-by: Hewenliang <hewenliang4@huawei.com>
Signed-off-by: yaowenbin <yaowenbin1@huawei.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/ui/tui/setup.c

@@ -170,9 +170,11 @@ void ui__exit(bool wait_for_ok)
 				    "Press any key...", 0);
 
 	SLtt_set_cursor_visibility(1);
+	if (!pthread_mutex_trylock(&ui__lock)) {
 		SLsmg_refresh();
 		SLsmg_reset_smg();
+		pthread_mutex_unlock(&ui__lock);
+	}
 	SLang_reset_tty();
-
 	perf_error__unregister(&perf_tui_eops);
 }