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 <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: [e-mail]
Link: http://lore.kernel.org/lkml/[e-mail]
Signed-off-by: Hewenliang <[e-mail]>
Signed-off-by: yaowenbin <[e-mail]>
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/ui/tui/setup.c

···
 				    "Press any key...", 0);
 
 	SLtt_set_cursor_visibility(1);
-	SLsmg_refresh();
-	SLsmg_reset_smg();
+	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);
 }