checkpatch.py: Add checks for easy-to-misuse APIs.

Signed-off-by: Peng He <hepeng.0320@bytedance.com>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Acked-by: Aaron Conole <aconole@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

utilities/checkpatch.py

@@ -620,6 +620,10 @@ def regex_error_factory(description):
     return lambda: print_error(description)
 
 
+def regex_warn_factory(description):
+    return lambda: print_warning(description)
+
+
 std_functions = [
         ('malloc', 'Use xmalloc() in place of malloc()'),
         ('calloc', 'Use xcalloc() in place of calloc()'),
@@ -636,6 +640,7 @@ std_functions = [
         ('assert', 'Use ovs_assert() in place of assert()'),
         ('error', 'Use ovs_error() in place of error()'),
 ]
+
 checks += [
     {'regex': r'(\.c|\.h)(\.in)?$',
      'match_name': None,
@@ -644,6 +649,21 @@ checks += [
      'print': regex_error_factory(description)}
     for (function_name, description) in std_functions]
 
+easy_to_misuse_api = [
+        ('ovsrcu_barrier',
+            'lib/ovs-rcu.c',
+            'Are you sure you need to use ovsrcu_barrier(), '
+            'in most cases ovsrcu_synchronize() will be fine?'),
+        ]
+
+checks += [
+    {'regex': r'(\.c)(\.in)?$',
+     'match_name': lambda x: x != location,
+     'prereq': lambda x: not is_comment_line(x),
+     'check': regex_function_factory(function_name),
+     'print': regex_warn_factory(description)}
+    for (function_name, location, description) in easy_to_misuse_api]
+
 
 def regex_operator_factory(operator):
     regex = re.compile(r'^[^#][^"\']*[^ "]%s[^ "\'][^"]*' % operator)
@@ -676,12 +696,22 @@ def get_file_type_checks(filename):
     global checks
     checkList = []
     for check in checks:
+        regex_check = True
+        match_check = True
+
         if check['regex'] is None and check['match_name'] is None:
             checkList.append(check)
+            continue
+
         if check['regex'] is not None and \
-           re.compile(check['regex']).search(filename) is not None:
-            checkList.append(check)
-        elif check['match_name'] is not None and check['match_name'](filename):
+           re.compile(check['regex']).search(filename) is None:
+            regex_check = False
+
+        if check['match_name'] is not None and \
+                not check['match_name'](filename):
+            match_check = False
+
+        if regex_check and match_check:
             checkList.append(check)
     return checkList