Helper to get open k[ret]probes. Fixes #236

src/python/bcc/__init__.py

@@ -708,3 +708,12 @@ class BPF(object):
             return "[unknown]"
         offset = int(addr - ksym_addrs[idx])
         return ksym_names[idx] + hex(offset)
+
+    @staticmethod
+    def get_open_kprobes():
+        """ get_open_kprobes()
+
+        Get the number of open K[ret]probes. Can be useful for scenarios where
+        event_re is used while attaching and detaching probes
+        """
+        return len(open_kprobes)

tests/cc/CMakeLists.txt

@@ -32,6 +32,8 @@ add_test(NAME py_test_trace3_c WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
   COMMAND ${TEST_WRAPPER} py_trace3_c sudo ${CMAKE_CURRENT_SOURCE_DIR}/test_trace3.py test_trace3.c)
 add_test(NAME py_test_trace4 WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
   COMMAND ${TEST_WRAPPER} py_trace4 sudo ${CMAKE_CURRENT_SOURCE_DIR}/test_trace4.py)
+add_test(NAME py_test_probe_count WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+  COMMAND ${TEST_WRAPPER} py_probe_count sudo ${CMAKE_CURRENT_SOURCE_DIR}/test_probe_count.py)
 add_test(NAME py_test_brb WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
   COMMAND ${TEST_WRAPPER} py_brb_c sudo ${CMAKE_CURRENT_SOURCE_DIR}/test_brb.py test_brb.c)
 add_test(NAME py_test_brb2 WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}

tests/cc/test_probe_count.py

+#!/usr/bin/env python
+# Copyright (c) Suchakra Sharma <suchakrapani.sharma@polymtl.ca>
+# Licensed under the Apache License, Version 2.0 (the "License")
+
+from bcc import BPF
+import os
+import sys
+from unittest import main, TestCase
+
+class TestKprobeCnt(TestCase):
+    def setUp(self):
+        self.b = BPF(text="""
+        int wololo(void *ctx) {
+          return 0;
+        }
+        """)
+        self.b.attach_kprobe(event_re="^vfs_.*", fn_name="wololo")
+
+    def test_attach1(self):
+        actual_cnt = 0
+        with open("/sys/kernel/debug/tracing/available_filter_functions") as f:
+            for line in f:
+                if str(line).startswith("vfs_"):
+                    actual_cnt += 1
+        open_cnt = self.b.get_open_kprobes()
+        self.assertEqual(actual_cnt, open_cnt)
+
+if __name__ == "__main__":
+    main()