netdev - [PATCH net-next 6/7] netconsole: docs: document the task name feature

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Message-Id: <20250221-netcons_current-v1-6-21c86ae8fc0d@debian.org>
Date: Fri, 21 Feb 2025 05:52:11 -0800
From: Breno Leitao <leitao@...ian.org>
To: Andrew Lunn <andrew+netdev@...n.ch>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Simon Horman <horms@...nel.org>, Jonathan Corbet <corbet@....net>, 
 Shuah Khan <shuah@...nel.org>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-doc@...r.kernel.org, linux-kselftest@...r.kernel.org, 
 Breno Leitao <leitao@...ian.org>, kernel-team@...a.com
Subject: [PATCH net-next 6/7] netconsole: docs: document the task name
 feature

Add documentation for the netconsole task name feature in
Documentation/networking/netconsole.rst. This explains how to enable
task name via configfs and demonstrates the output format.

The documentation includes:
- How to enable/disable the feature via taskname_enabled
- The format of the task name in the output
- An example showing the task name appearing in messages

Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 Documentation/networking/netconsole.rst | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/Documentation/networking/netconsole.rst b/Documentation/networking/netconsole.rst
index 84803c59968a3237012fab821f432eb531aba45c..ae82a6337a8d8a07a0d691e2da170f6cf70ae86f 100644
--- a/Documentation/networking/netconsole.rst
+++ b/Documentation/networking/netconsole.rst
@@ -240,6 +240,34 @@ Delete `userdata` entries with `rmdir`::

    It is recommended to not write user data values with newlines.

+Task name auto population in userdata
+-------------------------------------
+
+Inside the netconsole configfs hierarchy, there is a file called
+`taskname_enabled` under the `userdata` directory. This file is used to enable
+or disable the automatic task name population feature. This feature
+automatically populates the current task name that is scheduled in the CPU
+sneding the message.
+
+To enable task name auto-population::
+
+  echo 1 > /sys/kernel/config/netconsole/target1/userdata/taskname_enabled
+
+When this option is enabled, the netconsole messages will include an additional
+line in the userdata field with the format `taskname=<task name>`. This allows
+the receiver of the netconsole messages to easily find which application was
+currently scheduled when that message was generated, providing extra context
+for kernel messages and helping to categorize them.
+
+Example::
+
+  echo "This is a message" > /dev/kmsg
+  12,607,22085407756,-;This is a message
+   taskname=echo
+
+In this example, the message was generated while "echo" was the current
+scheduled process.
+
 CPU number auto population in userdata
 --------------------------------------

-- 
2.43.5