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>

2 files changed, 49 insertions, 0 deletions

diff --git a/Documentation/driver-api/xilinx/eemi.rst b/Documentation/driver-api/xilinx/eemi.rst
new file mode 100644
index 000000000..c1bc47b90
--- /dev/null
+++ b/Documentation/driver-api/xilinx/eemi.rst
@@ -0,0 +1,40 @@
+====================================
+Xilinx Zynq MPSoC EEMI Documentation
+====================================
+
+Xilinx Zynq MPSoC Firmware Interface
+-------------------------------------
+The zynqmp-firmware node describes the interface to platform firmware.
+ZynqMP has an interface to communicate with secure firmware. Firmware
+driver provides an interface to firmware APIs. Interface APIs can be
+used by any driver to communicate with PMC(Platform Management Controller).
+
+Embedded Energy Management Interface (EEMI)
+----------------------------------------------
+The embedded energy management interface is used to allow software
+components running across different processing clusters on a chip or
+device to communicate with a power management controller (PMC) on a
+device to issue or respond to power management requests.
+
+Any driver who wants to communicate with PMC using EEMI APIs use the
+functions provided for each function.
+
+IOCTL
+------
+IOCTL API is for device control and configuration. It is not a system
+IOCTL but it is an EEMI API. This API can be used by master to control
+any device specific configuration. IOCTL definitions can be platform
+specific. This API also manage shared device configuration.
+
+The following IOCTL IDs are valid for device control:
+- IOCTL_SET_PLL_FRAC_MODE	8
+- IOCTL_GET_PLL_FRAC_MODE	9
+- IOCTL_SET_PLL_FRAC_DATA	10
+- IOCTL_GET_PLL_FRAC_DATA	11
+
+Refer EEMI API guide [0] for IOCTL specific parameters and other EEMI APIs.
+
+References
+----------
+[0] Embedded Energy Management Interface (EEMI) API guide:
+    https://www.xilinx.com/support/documentation/user_guides/ug1200-eemi-api.pdf
diff --git a/Documentation/driver-api/xilinx/index.rst b/Documentation/driver-api/xilinx/index.rst
new file mode 100644
index 000000000..c95bda55d
--- /dev/null
+++ b/Documentation/driver-api/xilinx/index.rst
@@ -0,0 +1,9 @@
+
+===========
+Xilinx FPGA
+===========
+
+.. toctree::
+    :maxdepth: 1
+
+    eemi