Message-Id: <20251029-jk-fix-kernel-doc-duplicate-return-warning-v1-1-28ed58bec304@intel.com>
Date: Wed, 29 Oct 2025 11:30:42 -0700
From: Jacob Keller <jacob.e.keller@...el.com>
To: Jonathan Corbet <corbet@....net>, 
 Mauro Carvalho Chehab <mchehab+huawei@...nel.org>, 
 Jakub Kicinski <kuba@...nel.org>
Cc: netdev@...r.kernel.org, linux-doc@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Jacob Keller <jacob.e.keller@...el.com>
Subject: [PATCH] docs: kdoc: fix duplicate section warning message

The python version of the kernel-doc parser emits some strange warnings
with just a line number in certain cases:

$ ./scripts/kernel-doc -Wall -none 'include/linux/virtio_config.h'
Warning: 174
Warning: 184
Warning: 190
Warning: include/linux/virtio_config.h:226 No description found for return value of '__virtio_test_bit'
Warning: include/linux/virtio_config.h:259 No description found for return value of 'virtio_has_feature'
Warning: include/linux/virtio_config.h:283 No description found for return value of 'virtio_has_dma_quirk'
Warning: include/linux/virtio_config.h:392 No description found for return value of 'virtqueue_set_affinity'

I eventually tracked this down to the lone call of emit_msg() in the
KernelEntry class, which looks like:

  self.emit_msg(self.new_start_line, f"duplicate section name '{name}'\n")

This looks like all the other emit_msg calls. Unfortunately, the definition
within the KernelEntry class takes only a message parameter and not a line
number. The intended message is passed as the warning!

Pass the filename to the KernelEntry class, and use this to build the log
message in the same way as the KernelDoc class does.

To avoid future errors, mark the warning parameter for both emit_msg
definitions as a keyword-only argument. This will prevent accidentally
passing a string as the warning parameter in the future.

Also fix the call in dump_section to avoid an unnecessary additional
newline.

Fixes: e3b42e94cf10 ("scripts/lib/kdoc/kdoc_parser.py: move kernel entry to a class")
Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>
---
We recently discovered this while working on some netdev text
infrastructure. All of the duplicate section warnings are not being logged
properly, which was confusing the warning comparison logic we have for
testing patches in NIPA.

This appears to have been caused by the optimizations in:
https://lore.kernel.org/all/cover.1745564565.git.mchehab+huawei@kernel.org/

Before this fix:
$ ./scripts/kernel-doc -Wall -none 'include/linux/virtio_config.h'
Warning: 174
Warning: 184
Warning: 190
Warning: include/linux/virtio_config.h:226 No description found for return value of '__virtio_test_bit'
Warning: include/linux/virtio_config.h:259 No description found for return value of 'virtio_has_feature'
Warning: include/linux/virtio_config.h:283 No description found for return value of 'virtio_has_dma_quirk'
Warning: include/linux/virtio_config.h:392 No description found for return value of 'virtqueue_set_affinity'

After this fix:
$ ./scripts/kernel-doc -Wall -none 'include/linux/virtio_config.h'
Warning: include/linux/virtio_config.h:174 duplicate section name 'Return'
Warning: include/linux/virtio_config.h:184 duplicate section name 'Return'
Warning: include/linux/virtio_config.h:190 duplicate section name 'Return'
Warning: include/linux/virtio_config.h:226 No description found for return value of '__virtio_test_bit'
Warning: include/linux/virtio_config.h:259 No description found for return value of 'virtio_has_feature'
Warning: include/linux/virtio_config.h:283 No description found for return value of 'virtio_has_dma_quirk'
Warning: include/linux/virtio_config.h:392 No description found for return value of 'virtqueue_set_affinity'
---
 scripts/lib/kdoc/kdoc_parser.py | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/scripts/lib/kdoc/kdoc_parser.py b/scripts/lib/kdoc/kdoc_parser.py
index 2376f180b1fa..2acf9f6e5c35 100644
--- a/scripts/lib/kdoc/kdoc_parser.py
+++ b/scripts/lib/kdoc/kdoc_parser.py
@@ -254,7 +254,7 @@ SECTION_DEFAULT = "Description"  # default section
 
 class KernelEntry:
 
-    def __init__(self, config, ln):
+    def __init__(self, config, fname, ln):
         self.config = config
 
         self._contents = []
@@ -274,6 +274,8 @@ class KernelEntry:
 
         self.leading_space = None
 
+        self.fname = fname
+
         # State flags
         self.brcount = 0
         self.declaration_start_line = ln + 1
@@ -288,9 +290,11 @@ class KernelEntry:
         return '\n'.join(self._contents) + '\n'
 
     # TODO: rename to emit_message after removal of kernel-doc.pl
-    def emit_msg(self, log_msg, warning=True):
+    def emit_msg(self, ln, msg, *, warning=True):
         """Emit a message"""
 
+        log_msg = f"{self.fname}:{ln} {msg}"
+
         if not warning:
             self.config.log.info(log_msg)
             return
@@ -336,7 +340,7 @@ class KernelEntry:
                 # Only warn on user-specified duplicate section names
                 if name != SECTION_DEFAULT:
                     self.emit_msg(self.new_start_line,
-                                  f"duplicate section name '{name}'\n")
+                                  f"duplicate section name '{name}'")
                 # Treat as a new paragraph - add a blank line
                 self.sections[name] += '\n' + contents
             else:
@@ -387,15 +391,15 @@ class KernelDoc:
             self.emit_msg(0,
                           'Python 3.7 or later is required for correct results')
 
-    def emit_msg(self, ln, msg, warning=True):
+    def emit_msg(self, ln, msg, *, warning=True):
         """Emit a message"""
 
-        log_msg = f"{self.fname}:{ln} {msg}"
-
         if self.entry:
-            self.entry.emit_msg(log_msg, warning)
+            self.entry.emit_msg(ln, msg, warning=warning)
             return
 
+        log_msg = f"{self.fname}:{ln} {msg}"
+
         if warning:
             self.config.log.warning(log_msg)
         else:
@@ -440,7 +444,7 @@ class KernelDoc:
         variables used by the state machine.
         """
 
-        self.entry = KernelEntry(self.config, ln)
+        self.entry = KernelEntry(self.config, self.fname, ln)
 
         # State flags
         self.state = state.NORMAL

---
base-commit: e53642b87a4f4b03a8d7e5f8507fc3cd0c595ea6
change-id: 20251029-jk-fix-kernel-doc-duplicate-return-warning-bd57ea39c628

Best regards,
--  
Jacob Keller <jacob.e.keller@...el.com>

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