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, 202 insertions, 0 deletions

diff --git a/Documentation/driver-api/cxl/maturity-map.rst b/Documentation/driver-api/cxl/maturity-map.rst
new file mode 100644
index 000000000..282c1102d
--- /dev/null
+++ b/Documentation/driver-api/cxl/maturity-map.rst
@@ -0,0 +1,202 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+===========================================
+Compute Express Link Subsystem Maturity Map
+===========================================
+
+The Linux CXL subsystem tracks the dynamic `CXL specification
+<https://computeexpresslink.org/cxl-specification-landing-page>`_ that
+continues to respond to new use cases with new features, capability
+updates and fixes. At any given point some aspects of the subsystem are
+more mature than others. While the periodic pull requests summarize the
+`work being incorporated each merge window
+<https://lore.kernel.org/linux-cxl/?q=s%3APULL+s%3ACXL+tc%3Atorvalds+NOT+s%3ARe>`_,
+those do not always convey progress relative to a starting point and a
+future end goal.
+
+What follows is a coarse breakdown of the subsystem's major
+responsibilities along with a maturity score. The expectation is that
+the change-history of this document provides an overview summary of the
+subsystem maturation over time.
+
+The maturity scores are:
+
+- [3] Mature: Work in this area is complete and no changes on the horizon.
+  Note that this score can regress from one kernel release to the next
+  based on new test results or end user reports.
+
+- [2] Stabilizing: Major functionality operational, common cases are
+  mature, but known corner cases are still a work in progress.
+
+- [1] Initial: Capability that has exited the Proof of Concept phase, but
+  may still have significant gaps to close and fixes to apply as real
+  world testing occurs.
+
+- [0] Known gap: Feature is on a medium to long term horizon to
+  implement.  If the specification has a feature that does not even have
+  a '0' score in this document, there is a good chance that no one in
+  the linux-cxl@vger.kernel.org community has started to look at it.
+
+- X: Out of scope for kernel enabling, or kernel enabling not required
+
+Feature and Capabilities
+========================
+
+Enumeration / Provisioning
+--------------------------
+All of the fundamental enumeration an object model of the subsystem is
+in place, but there are several corner cases that are pending closure.
+
+
+* [2] CXL Window Enumeration
+
+  * [2] :ref:`Extended-linear memory-side cache <extended-linear>`
+  * [0] Low Memory-hole
+  * [X] Hetero-interleave
+
+* [2] Switch Enumeration
+
+  * [0] CXL register enumeration link-up dependency
+
+* [2] HDM Decoder Configuration
+
+  * [0] Decoder target and granularity constraints
+
+* [2] Performance enumeration
+
+  * [3] Endpoint CDAT
+  * [3] Switch CDAT
+  * [1] CDAT to Core-mm integration
+
+    * [1] x86
+    * [0] Arm64
+    * [0] All other arch.
+
+  * [0] Shared link
+
+* [2] Hotplug
+  (see CXL Window Enumeration)
+
+  * [0] Handle Soft Reserved conflicts
+
+* [0] :ref:`RCH link status <rch-link-status>`
+* [0] Fabrics / G-FAM (chapter 7)
+* [0] Global Access Endpoint
+
+
+RAS
+---
+In many ways CXL can be seen as a standardization of what would normally
+be handled by custom EDAC drivers. The open development here is
+mainly caused by the enumeration corner cases above.
+
+* [3] Component events (OS)
+* [2] Component events (FFM)
+* [1] Endpoint protocol errors (OS)
+* [1] Endpoint protocol errors (FFM)
+* [0] Switch protocol errors (OS)
+* [1] Switch protocol errors (FFM)
+* [2] DPA->HPA Address translation
+
+    * [1] XOR Interleave translation
+      (see CXL Window Enumeration)
+
+* [1] Memory Failure coordination
+* [0] Scrub control
+* [2] ACPI error injection EINJ
+
+  * [0] EINJ v2
+  * [X] Compliance DOE
+
+* [2] Native error injection
+* [3] RCH error handling
+* [1] VH error handling
+* [0] PPR
+* [0] Sparing
+* [0] Device built in test
+
+
+Mailbox commands
+----------------
+
+* [3] Firmware update
+* [3] Health / Alerts
+* [1] :ref:`Background commands <background-commands>`
+* [3] Sanitization
+* [3] Security commands
+* [3] RAW Command Debug Passthrough
+* [0] CEL-only-validation Passthrough
+* [0] Switch CCI
+* [3] Timestamp
+* [1] PMEM labels
+* [3] PMEM GPF / Dirty Shutdown
+* [0] Scan Media
+
+PMU
+---
+* [1] Type 3 PMU
+* [0] Switch USP/ DSP, Root Port
+
+Security
+--------
+
+* [X] CXL Trusted Execution Environment Security Protocol (TSP)
+* [X] CXL IDE (subsumed by TSP)
+
+Memory-pooling
+--------------
+
+* [1] Hotplug of LDs (via PCI hotplug)
+* [0] Dynamic Capacity Device (DCD) Support
+
+Multi-host sharing
+------------------
+
+* [0] Hardware coherent shared memory
+* [0] Software managed coherency shared memory
+
+Multi-host memory
+-----------------
+
+* [0] Dynamic Capacity Device Support
+* [0] Sharing
+
+Accelerator
+-----------
+
+* [0] Accelerator memory enumeration HDM-D (CXL 1.1/2.0 Type-2)
+* [0] Accelerator memory enumeration HDM-DB (CXL 3.0 Type-2)
+* [0] CXL.cache 68b (CXL 2.0)
+* [0] CXL.cache 256b Cache IDs (CXL 3.0)
+
+User Flow Support
+-----------------
+
+* [2] Inject & clear poison by region offset
+
+Details
+=======
+
+.. _extended-linear:
+
+* **Extended-linear memory-side cache**: An HMAT proposal to enumerate the presence of a
+  memory-side cache where the cache capacity extends the SRAT address
+  range capacity. `See the ECN
+  <https://lore.kernel.org/linux-cxl/6650e4f835a0e_195e294a8@dwillia2-mobl3.amr.corp.intel.com.notmuch/>`_
+  for more details:
+
+.. _rch-link-status:
+
+* **RCH Link Status**: RCH (Restricted CXL Host) topologies, end up
+  hiding some standard registers like PCIe Link Status / Capabilities in
+  the CXL RCRB (Root Complex Register Block).
+
+.. _background-commands:
+
+* **Background commands**: The CXL background command mechanism is
+  awkward as the single slot is monopolized potentially indefinitely by
+  various commands. A `cancel on conflict
+  <http://lore.kernel.org/r/66035c2e8ba17_770232948b@dwillia2-xfh.jf.intel.com.notmuch>`_
+  facility is needed to make sure the kernel can ensure forward progress
+  of priority commands.