Chinmaya Kajagar dff03860a7 scsi: zfcp: Trace return values of sysfs unit add store
sysfs unit add failures are seen during FCP devices manual SCSI LUN scans,
indicating the kernel cannot add a LUN, usually because the device is
offline, already exists, no memory or the target port is incorrectly
configured.

Add a new trace to debug zfcp sysfs unit add failures with tag id
ZFCP_DBF_HBA_UAS. This traces wwpn, fcp lun id, return value (error
condition) and associated hba of the device.

Typical unit add store failures as seen below example syslog messages,

Feb  2 10:47:25 systemd-udevd[823]: rport-1:0-2: /etc/udev/
rules.d/41-zfcp-lun-0.0.50c0:0x500507680b26c449:0x01d2000000000000.rules:10
Failed to write ATTR{/sys/devices/css0/0.0.0015/0.0.50c0/0x500507680b26c449
/unit_add}, ignoring: File exists

Feb  2 10:50:03 systemd-udevd[801]: rport-2:0-3: /etc/udev/
rules.d/41-zfcp-lun-0.0.50c0:0x500507680b26c448:0x01d2000000000000.rules:10
Failed to write ATTR{/sys/devices/css0/0.0.0015/0.0.50c0/0x500507680b26c448
/unit_add}, ignoring: Cannot allocate memory

Example zfcpdbf traces for both the errors:

Timestamp      : 2026-03-05-07:28:34:029797
Area           : HBA
Subarea        : 00
Level          : 3
Exception      : -
CPU ID         : 0002
Caller         : 0x000001fe345e6d0e
Record ID      : 6
Tag            : syuast2
Description    : syuast2 HBA, unit add, failed, unable to add unit
Request ID     : 0x00000000ffffffff
Request status : 0xffffffff
FSF cmnd       : 0xffffffff
FSF sequence no: 0xffffffff
WWPN           : 0x500507680b25c448
LUN            : 0x01d3000000000000
Return Value   : 0xfffffff4

Timestamp      : 2026-03-05-07:33:04:151807 <== the last record
Area           : HBA
Subarea        : 00
Level          : 3
Exception      : -
CPU ID         : 0002
Caller         : 0x000001fe345e6d0e
Record ID      : 6
Tag            : syuast2
Description    : syuast2 HBA, unit add, failed, unable to add unit
Request ID     : 0x00000000ffffffff
Request status : 0xffffffff
FSF cmnd       : 0xffffffff
FSF sequence no: 0xffffffff
WWPN           : 0x500507680b25c449
LUN            : 0x01d0000000000000
Return Value   : 0xfffffff4

Link: https://patch.msgid.link/20260728044857.2532646-4-niharp@linux.ibm.com
Signed-off-by: Chinmaya Kajagar <chinmayk@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2026-07-28 22:15:05 -04:00
2026-01-26 19:07:09 -08:00
2022-09-28 09:02:20 +02:00
2025-02-19 14:53:27 -07:00
2026-06-28 12:01:31 -07:00

Linux kernel
============

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer - Getting started with kernel development
* Academic Researcher - Studying kernel internals and architecture
* Security Expert - Hardening and vulnerability analysis
* Backport/Maintenance Engineer - Maintaining stable kernels
* System Administrator - Configuring and troubleshooting
* Maintainer - Leading subsystems and reviewing patches
* Hardware Vendor - Writing drivers for new hardware
* Distribution Maintainer - Packaging kernels for distros
* AI Coding Assistant - LLMs and AI-powered development tools


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst
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