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Linus Torvalds 5779de8d36 rtla updaets for v6.19:
- Officially add Tomas Glozar as a maintainer to RTLA tool
 
 - Add for_each_monitored_cpu() helper
 
   In multiple places, RTLA tools iterate over the list of CPUs running
   tracer threads.
 
   Use single helper instead of repeating the for/if combination.
 
 - Remove unused variable option_index in argument parsing
 
   RTLA tools use getopt_long() for argument parsing. For its last
   argument, an unused variable "option_index" is passed.
 
   Remove the variable and pass NULL to getopt_long() to shorten
   the naturally long parsing functions, and make them more readable.
 
 - Fix unassigned nr_cpus after code consolidation
 
   In recent code consolidation, timerlat tool cleanup, previously
   implemented separately for each tool, was moved to a common function
   timerlat_free().
 
   The cleanup relies on nr_cpus being set. This was not done in the new
   function, leaving the variable uninitialized.
 
   Initialize the variable properly, and remove silencing of compiler
   warning for uninitialized variables.
 
 - Stop tracing on user latency in BPF mode
 
   Despite the name, rtla-timerlat's -T/--thread option sets timerlat's
   stop_tracing_total_us option, which also stops tracing on
   return-from-user latency, not only on thread latency.
 
   Implement the same behavior also in BPF sample collection stop tracing
   handler to avoid a discrepancy and restore correspondence of behavior
   with the equivalent option of cyclictest.
 
 - Fix threshold actions always triggering
 
   A bug in threshold action logic caused the action to execute even
   if tracing did not stop because of threshold.
 
   Fix the logic to stop correctly.
 
 - Fix few minor issues in tests
 
   Extend tests that were shown to need it to 5s, fix osnoise test
   calling timerlat by mistake, and use new, more reliable output
   checking in timerlat's "top stop at failed action" test.
 
 - Do not print usage on argument parsing error
 
   RTLA prints the entire usage message on encountering errors in
   argument parsing, like a malformed CPU list.
 
   The usage message has gotten too long. Instead of printing it,
   use newly added fatal() helper function to simply exit with
   the error message, excluding the usage.
 
 - Fix unintuitive -C/--cgroup interface
 
   "-C cgroup" and "--cgroup cgroup" are invalid syntax, despite that
   being a common way to specify an option with argument. Moreover,
   using them fails silently and no cgroup is set.
 
   Create new helper function to unify the handling of all such options
   and allow all of:
 
   -Xsomething
   -X=something
   -X something
 
   as well as the equivalent for the long option.
 
 - Fix -a overriding -t argument filename
 
   Fix a bug where -a following -t custom_file.txt overrides the custom
   filename with the default timerlat_trace.txt.
 
 - Stop tracing correctly on multiple events at once
 
   In some race scenarios, RTLA BPF sample collection might send multiple
   stop tracing events via the BPF ringbuffer at once.
 
   Compare the number of events for != 0 instead of == 1 to cover for
   this scenario and stop tracing properly.
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Merge tag 'trace-tools-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull rtla trace tooling updates from Steven Rostedt:

 - Officially add Tomas Glozar as a maintainer to RTLA tool

 - Add for_each_monitored_cpu() helper

   In multiple places, RTLA tools iterate over the list of CPUs running
   tracer threads.

   Use single helper instead of repeating the for/if combination.

 - Remove unused variable option_index in argument parsing

   RTLA tools use getopt_long() for argument parsing. For its last
   argument, an unused variable "option_index" is passed.

   Remove the variable and pass NULL to getopt_long() to shorten the
   naturally long parsing functions, and make them more readable.

 - Fix unassigned nr_cpus after code consolidation

   In recent code consolidation, timerlat tool cleanup, previously
   implemented separately for each tool, was moved to a common function
   timerlat_free().

   The cleanup relies on nr_cpus being set. This was not done in the new
   function, leaving the variable uninitialized.

   Initialize the variable properly, and remove silencing of compiler
   warning for uninitialized variables.

 - Stop tracing on user latency in BPF mode

   Despite the name, rtla-timerlat's -T/--thread option sets timerlat's
   stop_tracing_total_us option, which also stops tracing on
   return-from-user latency, not only on thread latency.

   Implement the same behavior also in BPF sample collection stop
   tracing handler to avoid a discrepancy and restore correspondence of
   behavior with the equivalent option of cyclictest.

 - Fix threshold actions always triggering

   A bug in threshold action logic caused the action to execute even if
   tracing did not stop because of threshold.

   Fix the logic to stop correctly.

 - Fix few minor issues in tests

   Extend tests that were shown to need it to 5s, fix osnoise test
   calling timerlat by mistake, and use new, more reliable output
   checking in timerlat's "top stop at failed action" test.

 - Do not print usage on argument parsing error

   RTLA prints the entire usage message on encountering errors in
   argument parsing, like a malformed CPU list.

   The usage message has gotten too long. Instead of printing it, use
   newly added fatal() helper function to simply exit with the error
   message, excluding the usage.

 - Fix unintuitive -C/--cgroup interface

   "-C cgroup" and "--cgroup cgroup" are invalid syntax, despite that
   being a common way to specify an option with argument. Moreover,
   using them fails silently and no cgroup is set.

   Create new helper function to unify the handling of all such options
   and allow all of:

     -Xsomething
     -X=something
     -X something

   as well as the equivalent for the long option.

 - Fix -a overriding -t argument filename

   Fix a bug where -a following -t custom_file.txt overrides the custom
   filename with the default timerlat_trace.txt.

 - Stop tracing correctly on multiple events at once

   In some race scenarios, RTLA BPF sample collection might send
   multiple stop tracing events via the BPF ringbuffer at once.

   Compare the number of events for != 0 instead of == 1 to cover for
   this scenario and stop tracing properly.

* tag 'trace-tools-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  rtla/timerlat: Exit top main loop on any non-zero wait_retval
  rtla/tests: Don't rely on matching ^1ALL
  rtla: Fix -a overriding -t argument
  rtla: Fix -C/--cgroup interface
  tools/rtla: Replace osnoise_hist_usage("...") with fatal("...")
  tools/rtla: Replace osnoise_top_usage("...") with fatal("...")
  tools/rtla: Replace timerlat_hist_usage("...") with fatal("...")
  tools/rtla: Replace timerlat_top_usage("...") with fatal("...")
  tools/rtla: Add fatal() and replace error handling pattern
  rtla/tests: Fix osnoise test calling timerlat
  rtla/tests: Extend action tests to 5s
  tools/rtla: Fix --on-threshold always triggering
  rtla/timerlat_bpf: Stop tracing on user latency
  tools/rtla: Fix unassigned nr_cpus
  tools/rtla: Remove unused optional option_index
  tools/rtla: Add for_each_monitored_cpu() helper
  MAINTAINERS: Add Tomas Glozar as a maintainer to RTLA tool
2025-12-05 09:34:01 -08:00
Documentation rtla updaets for v6.19: 2025-12-05 09:34:01 -08:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
arch IOMMU Updates for Linux v6.19 2025-12-04 18:05:06 -08:00
block VFIO updates for v6.19-rc1 2025-12-04 18:42:48 -08:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto Networking changes for 6.19. 2025-12-03 17:24:33 -08:00
drivers hardening updates for v6.19-rc1 2025-12-05 09:11:02 -08:00
fs pstore update for v6.19-rc1 2025-12-05 09:08:13 -08:00
include hardening updates for v6.19-rc1 2025-12-05 09:11:02 -08:00
init drm-next for 6.19-rc1: 2025-12-04 08:53:30 -08:00
io_uring for-6.19/io_uring-20251201 2025-12-03 18:58:57 -08:00
ipc vfs-6.19-rc1.fd_prepare.fs 2025-12-01 17:32:07 -08:00
kernel VFIO updates for v6.19-rc1 2025-12-04 18:42:48 -08:00
lib sound updates for 6.19-rc1 2025-12-04 10:08:40 -08:00
mm VFIO updates for v6.19-rc1 2025-12-04 18:42:48 -08:00
net for-6.19/io_uring-20251201 2025-12-03 18:58:57 -08:00
rust pwm: Changes for v6.19-rc1 2025-12-04 11:04:38 -08:00
samples VFIO updates for v6.19-rc1 2025-12-04 18:42:48 -08:00
scripts Devicetree updates for v6.19: 2025-12-04 15:50:37 -08:00
security Capabilities patch for v6.19 2025-12-04 20:10:28 -08:00
sound firewire updates for v6.19 2025-12-04 12:26:36 -08:00
tools rtla updaets for v6.19: 2025-12-05 09:34:01 -08:00
usr initramfs: add gen_init_cpio to hostprogs unconditionally 2025-11-26 21:55:40 +01:00
virt A large overhaul of the restartable sequences and CID management: 2025-12-02 08:48:53 -08:00
.clang-format IOMMU Updates for Linux v6.19 2025-12-04 18:05:06 -08:00
.clippy.toml rust: clean Rust 1.88.0's warning about `clippy::disallowed_macros` configuration 2025-05-07 00:11:47 +02:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: kbuild: add proc macro library support 2025-11-24 17:15:36 +01:00
.mailmap IOMMU Updates for Linux v6.19 2025-12-04 18:05:06 -08:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml
COPYING
CREDITS MAINTAINERS: mark ISDN subsystem as orphan 2025-10-27 17:49:45 -07:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS rtla updaets for v6.19: 2025-12-05 09:34:01 -08:00
Makefile hardening updates for v6.19-rc1 2025-12-05 09:11:02 -08:00
README README: restructure with role-based documentation and guidelines 2025-11-29 08:40:33 -07:00

README

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


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



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