Fix incorrect lost_cb type in Python

src/python/bcc/table.py

@@ -532,7 +532,7 @@ class PerfEventArray(ArrayBase):
                     exit()
                 else:
                     raise e
-        def lost_cb_(lost):
+        def lost_cb_(_, lost):
             try:
                 lost_cb(lost)
             except IOError as e:

tests/python/test_array.py

@@ -49,6 +49,9 @@ class TestArray(TestCase):
             event = ct.cast(data, ct.POINTER(Data)).contents
             self.counter += 1
 
+        def lost_cb(lost):
+            self.assertGreater(lost, 0)
+
         text = """
 BPF_PERF_OUTPUT(events);
 int kprobe__sys_nanosleep(void *ctx) {
@@ -60,7 +63,7 @@ int kprobe__sys_nanosleep(void *ctx) {
 }
 """
         b = BPF(text=text)
-        b["events"].open_perf_buffer(cb)
+        b["events"].open_perf_buffer(cb, lost_cb=lost_cb)
         time.sleep(0.1)
         b.kprobe_poll()
         self.assertGreater(self.counter, 0)
@@ -77,6 +80,9 @@ int kprobe__sys_nanosleep(void *ctx) {
             event = ct.cast(data, ct.POINTER(Data)).contents
             self.events.append(event)
 
+        def lost_cb(lost):
+            self.assertGreater(lost, 0)
+
         text = """
 BPF_PERF_OUTPUT(events);
 int kprobe__sys_nanosleep(void *ctx) {
@@ -88,7 +94,7 @@ int kprobe__sys_nanosleep(void *ctx) {
 }
 """
         b = BPF(text=text)
-        b["events"].open_perf_buffer(cb)
+        b["events"].open_perf_buffer(cb, lost_cb=lost_cb)
         online_cpus = get_online_cpus()
         for cpu in online_cpus:
             subprocess.call(['taskset', '-c', str(cpu), 'sleep', '0.1'])