Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 381 insertions, 0 deletions

diff --git a/Documentation/process/kernel-docs.rst b/Documentation/process/kernel-docs.rst
new file mode 100644
index 000000000..c67ac12cf
--- /dev/null
+++ b/Documentation/process/kernel-docs.rst
@@ -0,0 +1,381 @@
+.. _kernel_docs:
+
+Index of Further Kernel Documentation
+=====================================
+
+The need for a document like this one became apparent in the linux-kernel
+mailing list as the same questions, asking for pointers to information,
+appeared again and again.
+
+Fortunately, as more and more people get to GNU/Linux, more and more get
+interested in the Kernel. But reading the sources is not always enough. It
+is easy to understand the code, but miss the concepts, the philosophy and
+design decisions behind this code.
+
+Unfortunately, not many documents are available for beginners to start.
+And, even if they exist, there was no "well-known" place which kept track
+of them. These lines try to cover this lack.
+
+PLEASE, if you know any paper not listed here or write a new document,
+include a reference to it here, following the kernel's patch submission
+process. Any corrections, ideas or comments are also welcome.
+
+All documents are cataloged with the following fields: the document's
+"Title", the "Author"/s, the "URL" where they can be found, some "Keywords"
+helpful when searching for specific topics, and a brief "Description" of
+the Document.
+
+.. note::
+
+   The documents on each section of this document are ordered by its
+   published date, from the newest to the oldest. The maintainer(s) should
+   periodically retire resources as they become obsolete or outdated; with
+   the exception of foundational books.
+
+Docs at the Linux Kernel tree
+-----------------------------
+
+The Sphinx books should be built with ``make {htmldocs | pdfdocs | epubdocs}``.
+
+    * Name: **linux/Documentation**
+
+      :Author: Many.
+      :Location: Documentation/
+      :Keywords: text files, Sphinx.
+      :Description: Documentation that comes with the kernel sources,
+        inside the Documentation directory. Some pages from this document
+        (including this document itself) have been moved there, and might
+        be more up to date than the web version.
+
+On-line docs
+------------
+
+    * Title: **Linux Kernel Mailing List Glossary**
+
+      :Author: various
+      :URL: https://kernelnewbies.org/KernelGlossary
+      :Date: rolling version
+      :Keywords: glossary, terms, linux-kernel.
+      :Description: From the introduction: "This glossary is intended as
+        a brief description of some of the acronyms and terms you may hear
+        during discussion of the Linux kernel".
+
+    * Title: **The Linux Kernel Module Programming Guide**
+
+      :Author: Peter Jay Salzman, Michael Burian, Ori Pomerantz, Bob Mottram,
+        Jim Huang.
+      :URL: https://sysprog21.github.io/lkmpg/
+      :Date: 2021
+      :Keywords: modules, GPL book, /proc, ioctls, system calls,
+        interrupt handlers .
+      :Description: A very nice GPL book on the topic of modules
+        programming. Lots of examples. Currently the new version is being
+        actively maintained at https://github.com/sysprog21/lkmpg.
+
+Published books
+---------------
+
+    * Title: **The Linux Memory Manager**
+
+      :Author: Lorenzo Stoakes
+      :Publisher: No Starch Press
+      :Date: February 2025
+      :Pages: 1300
+      :ISBN: 978-1718504462
+      :Notes: Memory management. Full draft available as early access for
+              pre-order, full release scheduled for Fall 2025. See
+              https://nostarch.com/linux-memory-manager for further info.
+
+    * Title: **Practical Linux System Administration: A Guide to Installation, Configuration, and Management, 1st Edition**
+
+      :Author: Kenneth Hess
+      :Publisher: O'Reilly Media
+      :Date: May, 2023
+      :Pages: 246
+      :ISBN: 978-1098109035
+      :Notes: System administration
+
+    * Title: **Linux Kernel Debugging: Leverage proven tools and advanced techniques to effectively debug Linux kernels and kernel modules**
+
+      :Author: Kaiwan N Billimoria
+      :Publisher: Packt Publishing Ltd
+      :Date: August, 2022
+      :Pages: 638
+      :ISBN: 978-1801075039
+      :Notes: Debugging book
+
+    * Title: **Linux Kernel Programming: A Comprehensive Guide to Kernel Internals, Writing Kernel Modules, and Kernel Synchronization**
+
+      :Author: Kaiwan N Billimoria
+      :Publisher: Packt Publishing Ltd
+      :Date: March, 2021 (Second Edition published in 2024)
+      :Pages: 754
+      :ISBN: 978-1789953435 (Second Edition ISBN is 978-1803232225)
+
+    * Title: **Linux Kernel Programming Part 2 - Char Device Drivers and Kernel Synchronization: Create user-kernel interfaces, work with peripheral I/O, and handle hardware interrupts**
+
+      :Author: Kaiwan N Billimoria
+      :Publisher: Packt Publishing Ltd
+      :Date: March, 2021
+      :Pages: 452
+      :ISBN: 978-1801079518
+
+    * Title: **Linux System Programming: Talking Directly to the Kernel and C Library**
+
+      :Author: Robert Love
+      :Publisher: O'Reilly Media
+      :Date: June, 2013
+      :Pages: 456
+      :ISBN: 978-1449339531
+      :Notes: Foundational book
+
+    * Title: **Linux Kernel Development, 3rd Edition**
+
+      :Author: Robert Love
+      :Publisher: Addison-Wesley
+      :Date: July, 2010
+      :Pages: 440
+      :ISBN: 978-0672329463
+      :Notes: Foundational book
+
+.. _ldd3_published:
+
+    * Title: **Linux Device Drivers, 3rd Edition**
+
+      :Authors: Jonathan Corbet, Alessandro Rubini, and Greg Kroah-Hartman
+      :Publisher: O'Reilly & Associates
+      :Date: 2005
+      :Pages: 636
+      :ISBN: 0-596-00590-3
+      :Notes: Foundational book. Further information in
+        http://www.oreilly.com/catalog/linuxdrive3/
+        PDF format, URL: https://lwn.net/Kernel/LDD3/
+
+    * Title: **The Design of the UNIX Operating System**
+
+      :Author: Maurice J. Bach
+      :Publisher: Prentice Hall
+      :Date: 1986
+      :Pages: 471
+      :ISBN: 0-13-201757-1
+      :Notes: Foundational book
+
+Miscellaneous
+-------------
+
+    * Name: **Cross-Referencing Linux**
+
+      :URL: https://elixir.bootlin.com/
+      :Keywords: Browsing source code.
+      :Description: Another web-based Linux kernel source code browser.
+        Lots of cross references to variables and functions. You can see
+        where they are defined and where they are used.
+
+    * Name: **Linux Weekly News**
+
+      :URL: https://lwn.net
+      :Keywords: latest kernel news.
+      :Description: The title says it all. There's a fixed kernel section
+        summarizing developers' work, bug fixes, new features and versions
+        produced during the week.
+
+    * Name: **The home page of Linux-MM**
+
+      :Author: The Linux-MM team.
+      :URL: https://linux-mm.org/
+      :Keywords: memory management, Linux-MM, mm patches, TODO, docs,
+        mailing list.
+      :Description: Site devoted to Linux Memory Management development.
+        Memory related patches, HOWTOs, links, mm developers... Don't miss
+        it if you are interested in memory management development!
+
+    * Name: **Kernel Newbies IRC Channel and Website**
+
+      :URL: https://www.kernelnewbies.org
+      :Keywords: IRC, newbies, channel, asking doubts.
+      :Description: #kernelnewbies on irc.oftc.net.
+        #kernelnewbies is an IRC network dedicated to the 'newbie'
+        kernel hacker. The audience mostly consists of people who are
+        learning about the kernel, working on kernel projects or
+        professional kernel hackers that want to help less seasoned kernel
+        people.
+        #kernelnewbies is on the OFTC IRC Network.
+        Try irc.oftc.net as your server and then /join #kernelnewbies.
+        The kernelnewbies website also hosts articles, documents, FAQs...
+
+    * Name: **linux-kernel mailing list archives and search engines**
+
+      :URL: https://subspace.kernel.org
+      :URL: https://lore.kernel.org
+      :Keywords: linux-kernel, archives, search.
+      :Description: Some of the linux-kernel mailing list archivers. If
+        you have a better/another one, please let me know.
+
+    * Name: **The Linux Foundation YouTube channel**
+
+      :URL: https://www.youtube.com/user/thelinuxfoundation
+      :Keywords: linux, videos, linux-foundation, youtube.
+      :Description: The Linux Foundation uploads video recordings of their
+        collaborative events, Linux conferences including LinuxCon, and
+        other original research and content related to Linux and software
+        development.
+
+Rust
+----
+
+    * Title: **Rust for Linux**
+
+      :Author: various
+      :URL: https://rust-for-linux.com/
+      :Date: rolling version
+      :Keywords: glossary, terms, linux-kernel, rust.
+      :Description: From the website: "Rust for Linux is the project adding
+        support for the Rust language to the Linux kernel. This website is
+        intended as a hub of links, documentation and resources related to
+        the project".
+
+    * Title: **Learn Rust the Dangerous Way**
+
+      :Author: Cliff L. Biffle
+      :URL: https://cliffle.com/p/dangerust/
+      :Date: Accessed Sep 11 2024
+      :Keywords: rust, blog.
+      :Description: From the website: "LRtDW is a series of articles
+        putting Rust features in context for low-level C programmers who
+        maybe don’t have a formal CS background — the sort of people who
+        work on firmware, game engines, OS kernels, and the like.
+        Basically, people like me.". It illustrates line-by-line
+        conversions from C to Rust.
+
+    * Title: **The Rust Book**
+
+      :Author: Steve Klabnik and Carol Nichols, with contributions from the
+        Rust community
+      :URL: https://doc.rust-lang.org/book/
+      :Date: Accessed Sep 11 2024
+      :Keywords: rust, book.
+      :Description: From the website: "This book fully embraces the
+        potential of Rust to empower its users. It’s a friendly and
+        approachable text intended to help you level up not just your
+        knowledge of Rust, but also your reach and confidence as a
+        programmer in general. So dive in, get ready to learn—and welcome
+        to the Rust community!".
+
+    * Title: **Rust for the Polyglot Programmer**
+
+      :Author: Ian Jackson
+      :URL: https://www.chiark.greenend.org.uk/~ianmdlvl/rust-polyglot/index.html
+      :Date: December 2022
+      :Keywords: rust, blog, tooling.
+      :Description: From the website: "There are many guides and
+        introductions to Rust. This one is something different: it is
+        intended for the experienced programmer who already knows many
+        other programming languages. I try to be comprehensive enough to be
+        a starting point for any area of Rust, but to avoid going into too
+        much detail except where things are not as you might expect. Also
+        this guide is not entirely free of opinion, including
+        recommendations of libraries (crates), tooling, etc.".
+
+    * Title: **Fasterthanli.me**
+
+      :Author: Amos Wenger
+      :URL: https://fasterthanli.me/
+      :Date: Accessed Sep 11 2024
+      :Keywords: rust, blog, news.
+      :Description: From the website: "I make articles and videos about how
+        computers work. My content is long-form, didactic and exploratory
+        — and often an excuse to teach Rust!".
+
+    * Title: **Comprehensive Rust**
+
+      :Author: Android team at Google
+      :URL: https://google.github.io/comprehensive-rust/
+      :Date: Accessed Sep 13 2024
+      :Keywords: rust, blog.
+      :Description: From the website: "The course covers the full spectrum
+        of Rust, from basic syntax to advanced topics like generics and
+        error handling".
+
+    * Title: **The Embedded Rust Book**
+
+      :Author: Multiple contributors, mostly Jorge Aparicio
+      :URL: https://docs.rust-embedded.org/book/
+      :Date: Accessed Sep 13 2024
+      :Keywords: rust, blog.
+      :Description: From the website: "An introductory book about using
+        the Rust Programming Language on "Bare Metal" embedded systems,
+        such as Microcontrollers".
+
+   * Title: **Experiment: Improving the Rust Book**
+
+      :Author: Cognitive Engineering Lab at Brown University
+      :URL: https://rust-book.cs.brown.edu/
+      :Date: Accessed Sep 22 2024
+      :Keywords: rust, blog.
+      :Description: From the website: "The goal of this experiment is to
+        evaluate and improve the content of the Rust Book to help people
+        learn Rust more effectively.".
+
+   * Title: **New Rustacean** (podcast)
+
+      :Author: Chris Krycho
+      :URL: https://newrustacean.com/
+      :Date: Accessed Sep 22 2024
+      :Keywords: rust, podcast.
+      :Description: From the website: "This is a podcast about learning
+        the programming language Rust—from scratch! Apart from this spiffy
+        landing page, all the site content is built with Rust's own
+        documentation tools.".
+
+   * Title: **Opsem-team** (repository)
+
+      :Author: Operational semantics team
+      :URL: https://github.com/rust-lang/opsem-team/tree/main
+      :Date: Accessed Sep 22 2024
+      :Keywords: rust, repository.
+      :Description: From the README: "The opsem team is the successor of
+        the unsafe-code-guidelines working group and responsible for
+        answering many of the difficult questions about the semantics of
+        unsafe Rust".
+
+    * Title: **You Can't Spell Trust Without Rust**
+
+      :Author: Alexis Beingessner
+      :URL: https://repository.library.carleton.ca/downloads/1j92g820w?locale=en
+      :Date: 2015
+      :Keywords: rust, master, thesis.
+      :Description: This thesis focuses on Rust's ownership system, which
+        ensures memory safety by controlling data manipulation and
+        lifetime, while also highlighting its limitations and comparing it
+        to similar systems in Cyclone and C++.
+
+    * Name: **Linux Plumbers (LPC) 2024 Rust presentations**
+
+      :Title: Rust microconference
+      :URL: https://lpc.events/event/18/sessions/186/#20240918
+      :Title: Rust for Linux
+      :URL: https://lpc.events/event/18/contributions/1912/
+      :Title: Journey of a C kernel engineer starting a Rust driver project
+      :URL: https://lpc.events/event/18/contributions/1911/
+      :Title: Crafting a Linux kernel scheduler that runs in user-space
+        using Rust
+      :URL: https://lpc.events/event/18/contributions/1723/
+      :Title: openHCL: A Linux and Rust based paravisor
+      :URL: https://lpc.events/event/18/contributions/1956/
+      :Keywords: rust, lpc, presentations.
+      :Description: A number of LPC talks related to Rust.
+
+    * Name: **The Rustacean Station Podcast**
+
+      :URL: https://rustacean-station.org/
+      :Keywords: rust, podcasts.
+      :Description: A community project for creating podcast content for
+        the Rust programming language.
+
+-------
+
+This document was originally based on:
+
+ https://www.dit.upm.es/~jmseyas/linux/kernel/hackers-docs.html
+
+and written by Juan-Mariano de Goyeneche