ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 175 insertions, 0 deletions

diff --git a/Documentation/netlink/specs/dev-energymodel.yaml b/Documentation/netlink/specs/dev-energymodel.yaml
new file mode 100644
index 000000000..11faabfdf
--- /dev/null
+++ b/Documentation/netlink/specs/dev-energymodel.yaml
@@ -0,0 +1,175 @@
+# SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
+#
+# Copyright (c) 2025 Valve Corporation.
+#
+---
+name: dev-energymodel
+
+doc: |
+  Energy model netlink interface to notify its changes.
+
+protocol: genetlink
+
+uapi-header: linux/dev_energymodel.h
+
+definitions:
+  -
+    type: flags
+    name: perf-state-flags
+    entries:
+      -
+        name: perf-state-inefficient
+        doc: >-
+          The performance state is inefficient. There is in this perf-domain,
+          another performance state with a higher frequency but a lower or
+          equal power cost.
+  -
+    type: flags
+    name: perf-domain-flags
+    entries:
+      -
+        name: perf-domain-microwatts
+        doc: >-
+          The power values are in micro-Watts or some other scale.
+      -
+        name: perf-domain-skip-inefficiencies
+        doc: >-
+          Skip inefficient states when estimating energy consumption.
+      -
+        name: perf-domain-artificial
+        doc: >-
+          The power values are artificial and might be created by platform
+          missing real power information.
+
+attribute-sets:
+  -
+    name: perf-domain
+    doc: >-
+      Information on a single performance domains.
+    attributes:
+      -
+        name: pad
+        type: pad
+      -
+        name: perf-domain-id
+        type: u32
+        doc: >-
+          A unique ID number for each performance domain.
+      -
+        name: flags
+        type: u64
+        doc: >-
+          Bitmask of performance domain flags.
+        enum: perf-domain-flags
+      -
+        name: cpus
+        type: u64
+        multi-attr: true
+        doc: >-
+          CPUs that belong to this performance domain.
+  -
+    name: perf-table
+    doc: >-
+      Performance states table.
+    attributes:
+      -
+        name: perf-domain-id
+        type: u32
+        doc: >-
+          A unique ID number for each performance domain.
+      -
+        name: perf-state
+        type: nest
+        nested-attributes: perf-state
+        multi-attr: true
+  -
+    name: perf-state
+    doc: >-
+      Performance state of a performance domain.
+    attributes:
+      -
+        name: pad
+        type: pad
+      -
+        name: performance
+        type: u64
+        doc: >-
+          CPU performance (capacity) at a given frequency.
+      -
+        name: frequency
+        type: u64
+        doc: >-
+          The frequency in KHz, for consistency with CPUFreq.
+      -
+        name: power
+        type: u64
+        doc: >-
+          The power consumed at this level (by 1 CPU or by a registered
+          device). It can be a total power: static and dynamic.
+      -
+        name: cost
+        type: u64
+        doc: >-
+          The cost coefficient associated with this level, used during energy
+          calculation. Equal to: power * max_frequency / frequency.
+      -
+        name: flags
+        type: u64
+        doc: >-
+          Bitmask of performance state flags.
+        enum: perf-state-flags
+
+operations:
+  list:
+    -
+      name: get-perf-domains
+      attribute-set: perf-domain
+      doc: Get the list of information for all performance domains.
+      do:
+        request:
+          attributes:
+            - perf-domain-id
+        reply:
+          attributes: &perf-domain-attrs
+            - pad
+            - perf-domain-id
+            - flags
+            - cpus
+      dump:
+        reply:
+          attributes: *perf-domain-attrs
+    -
+      name: get-perf-table
+      attribute-set: perf-table
+      doc: Get the energy model table of a performance domain.
+      do:
+        request:
+          attributes:
+            - perf-domain-id
+        reply:
+          attributes:
+            - perf-domain-id
+            - perf-state
+    -
+      name: perf-domain-created
+      doc: A performance domain is created.
+      notify: get-perf-table
+      mcgrp: event
+    -
+      name: perf-domain-updated
+      doc: A performance domain is updated.
+      notify: get-perf-table
+      mcgrp: event
+    -
+      name: perf-domain-deleted
+      doc: A performance domain is deleted.
+      attribute-set: perf-table
+      event:
+        attributes:
+          - perf-domain-id
+      mcgrp: event
+
+mcast-groups:
+  list:
+    -
+      name: event