docs: sphinx/kernel_abi: avoid warnings during Sphinx module init

Sphinx logging system doesn't like warnings during module load,
as it understands that such logs are produced at the wrong time:

	WARNING: while setting up extension automarkup: /sys/devices/system/cpu/cpuX/topology/physical_package_id is defined 2 times: /new_devel/v4l/docs/Documentation/ABI/stable/sysfs-devices-system-cpu:27; /new_devel/v4l/docs/Documentation/ABI/testing/sysfs-devices-system-cpu:70
	WARNING: while setting up extension automarkup: /sys/devices/system/cpu/cpuX/topology/ppin is defined 2 times: /new_devel/v4l/docs/Documentation/ABI/stable/sysfs-devices-system-cpu:89; /new_devel/v4l/docs/Documentation/ABI/testing/sysfs-devices-system-cpu:70

So, use a function to allocate/process ABI files and use it to
be called at kernel_abi.py, as automarkup also needs it to
produce the right cross-references.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/b0e79dc60d556e3b39fa6774d3b7bf734b73f352.1739182025.git.mchehab+huawei@kernel.org

Documentation/sphinx/automarkup.py

@@ -11,7 +11,7 @@ from sphinx.errors import NoUri
 import re
 from itertools import chain
 
-from kernel_abi import kernel_abi
+from kernel_abi import get_kernel_abi
 
 #
 # Python 2 lacks re.ASCII...
@@ -287,6 +287,8 @@ def markup_abi_ref(docname, app, match):
     #
     # Go through the dance of getting an xref out of the std domain
     #
+    kernel_abi = get_kernel_abi()
+
     fname = match.group(1)
     target = kernel_abi.xref(fname)
 

Documentation/sphinx/kernel_abi.py

@@ -52,10 +52,23 @@ __version__ = "1.0"
 logger = logging.getLogger('kernel_abi')
 path = os.path.join(srctree, "Documentation/ABI")
 
-# Parse ABI symbols only once
-kernel_abi = AbiParser(path, logger=logger)
-kernel_abi.parse_abi()
-kernel_abi.check_issues()
+_kernel_abi = None
+
+def get_kernel_abi():
+    u"""
+    Initialize kernel_abi global var, if not initialized yet.
+
+    This is needed to avoid warnings during Sphinx module initialization.
+    """
+    global _kernel_abi
+
+    if not _kernel_abi:
+        # Parse ABI symbols only once
+        _kernel_abi = AbiParser(path, logger=logger)
+        _kernel_abi.parse_abi()
+        _kernel_abi.check_issues()
+
+    return _kernel_abi
 
 def setup(app):
 
@@ -83,6 +96,8 @@ class KernelCmd(Directive):
     }
 
     def run(self):
+        kernel_abi = get_kernel_abi()
+
         doc = self.state.document
         if not doc.settings.file_insertion_enabled:
             raise self.warning("docutils: file insertion disabled")