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, 255 insertions, 0 deletions

diff --git a/tools/usb/usbip/README b/tools/usb/usbip/README
new file mode 100644
index 000000000..11971538f
--- /dev/null
+++ b/tools/usb/usbip/README
@@ -0,0 +1,255 @@
+#
+# README for usbip-utils
+#
+# Copyright (C) 2011 matt mooney <mfm@muteddisk.com>
+#               2005-2008 Takahiro Hirofuchi
+
+[Overview]
+USB/IP protocol allows to pass USB device from server to client over the
+network. Server is a machine which provides (shares) a USB device. Client is
+a machine which uses USB device provided by server over the network.
+The USB device may be either physical device connected to a server or
+software entity created on a server using USB gadget subsystem.
+Whole project consists of four parts:
+
+    - usbip-vhci
+        A client side kernel module which provides a virtual USB Host Controller
+        and allows to import a USB device from a remote machine.
+
+    - usbip-host (stub driver)
+        A server side module which provides a USB device driver which can be
+        bound to a physical USB device to make it exportable.
+
+    - usbip-vudc
+        A server side module which provides a virtual USB Device Controller and allows
+        to export a USB device created using USB Gadget Subsystem.
+
+    - usbip-utils
+        A set of userspace tools used to handle connection and management.
+        Used on both sides.
+
+[Requirements]
+    - USB/IP device drivers
+        Found in the drivers/usb/usbip/ directory of the Linux kernel tree.
+
+    - libudev >= 2.0
+	libudev library
+
+    - libwrap0-dev
+	tcp wrapper library
+
+    - gcc >= 4.0
+
+    - libtool, automake >= 1.9, autoconf >= 2.5.0, pkg-config
+
+[Optional]
+    - hwdata
+        Contains USB device identification data.
+
+
+[Install]
+    0. Generate configuration scripts.
+	$ ./autogen.sh
+
+    1. Compile & install the userspace utilities.
+	$ ./configure [--with-tcp-wrappers=no] [--with-usbids-dir=<dir>]
+	$ make install
+
+    2. Compile & install USB/IP drivers.
+
+
+[Usage]
+On a server side there are two entities which can be shared.
+First of them is physical usb device connected to the machine.
+To make it available below steps should be executed:
+
+    server:# (Physically attach your USB device.)
+
+    server:# insmod usbip-core.ko
+    server:# insmod usbip-host.ko
+
+    server:# usbipd -D
+	- Start usbip daemon.
+
+    server:# usbip list -l
+	- List driver assignments for USB devices.
+
+    server:# usbip bind --busid 1-2
+	- Bind usbip-host.ko to the device with busid 1-2.
+	- The USB device 1-2 is now exportable to other hosts!
+	- Use `usbip unbind --busid 1-2' to stop exporting the device.
+
+Second of shareable entities is USB Gadget created using USB Gadget Subsystem
+on a server machine. To make it available below steps should be executed:
+
+    server:# (Create your USB gadget)
+        - Currently the most preferable way of creating a new USB gadget
+          is ConfigFS Composite Gadget. Please refer to its documentation
+          for details.
+        - See vudc_server_example.sh for a short example of USB gadget creation
+
+    server:# insmod usbip-core.ko
+    server:# insmod usbip-vudc.ko
+        - To create more than one instance of vudc use num module param
+
+    server:# (Bind gadget to one of available vudc)
+        - Assign your new gadget to USB/IP UDC
+        - Using ConfigFS interface you may do this simply by:
+            server:# cd /sys/kernel/config/usb_gadget/<gadget_name>
+            server:# echo "usbip-vudc.0" > UDC
+
+    server:# usbipd -D --device
+        - Start usbip daemon.
+
+To attach new device to client machine below commands should be used:
+
+    client:# insmod usbip-core.ko
+    client:# insmod vhci-hcd.ko
+
+    client:# usbip list --remote <host>
+	- List exported USB devices on the <host>.
+
+    client:# usbip attach --remote <host> --busid 1-2
+	- Connect the remote USB device.
+	- When using vudc on a server side busid is really vudc instance name.
+	  For example: usbip-vudc.0
+
+    client:# usbip port
+	- Show virtual port status.
+
+    client:# usbip detach --port <port>
+	- Detach the USB device.
+
+
+[Example]
+---------------------------
+	SERVER SIDE
+---------------------------
+Physically attach your USB devices to this host.
+
+    trois:# insmod path/to/usbip-core.ko
+    trois:# insmod path/to/usbip-host.ko
+    trois:# usbipd -D
+
+In another terminal, let's look up what USB devices are physically
+attached to this host.
+
+    trois:# usbip list -l
+    Local USB devices
+    =================
+     - busid 1-1 (05a9:a511)
+	     1-1:1.0
+
+     - busid 3-2 (0711:0902)
+	     3-2:1.0
+
+     - busid 3-3.1 (08bb:2702)
+	     3-3.1:1.0
+	     3-3.1:1.1
+
+     - busid 3-3.2 (04bb:0206)
+	     3-3.2:1.0
+
+     - busid 3-3 (0409:0058)
+	     3-3:1.0
+
+     - busid 4-1 (046d:08b2)
+	     4-1:1.0
+	     4-1:1.1
+	     4-1:1.2
+
+     - busid 5-2 (058f:9254)
+	     5-2:1.0
+
+A USB storage device of busid 3-3.2 is now bound to the usb-storage
+driver. To export this device, we first mark the device as
+"exportable"; the device is bound to the usbip-host driver. Please
+remember you can not export a USB hub.
+
+Mark the device of busid 3-3.2 as exportable:
+
+    trois:# usbip --debug bind --busid 3-3.2
+    ...
+    usbip debug: usbip_bind.c:162:[unbind_other] 3-3.2:1.0 -> usb-storage
+    ...
+    bind device on busid 3-3.2: complete
+
+    trois:# usbip list -l
+    Local USB devices
+    =================
+    ...
+
+     - busid 3-3.2 (04bb:0206)
+	     3-3.2:1.0
+    ...
+
+---------------------------
+	CLIENT SIDE
+---------------------------
+First, let's list available remote devices that are marked as
+exportable on the host.
+
+    deux:# insmod path/to/usbip-core.ko
+    deux:# insmod path/to/vhci-hcd.ko
+
+    deux:# usbip list --remote 10.0.0.3
+    Exportable USB devices
+    ======================
+     - 10.0.0.3
+	    1-1: Prolific Technology, Inc. : unknown product (067b:3507)
+	       : /sys/devices/pci0000:00/0000:00:1f.2/usb1/1-1
+	       : (Defined at Interface level) / unknown subclass / unknown protocol (00/00/00)
+	       :  0 - Mass Storage / SCSI / Bulk (Zip) (08/06/50)
+
+	1-2.2.1: Apple Computer, Inc. : unknown product (05ac:0203)
+	       : /sys/devices/pci0000:00/0000:00:1f.2/usb1/1-2/1-2.2/1-2.2.1
+	       : (Defined at Interface level) / unknown subclass / unknown protocol (00/00/00)
+	       :  0 - Human Interface Devices / Boot Interface Subclass / Keyboard (03/01/01)
+
+	1-2.2.3: OmniVision Technologies, Inc. : OV511+ WebCam (05a9:a511)
+	       : /sys/devices/pci0000:00/0000:00:1f.2/usb1/1-2/1-2.2/1-2.2.3
+	       : (Defined at Interface level) / unknown subclass / unknown protocol (00/00/00)
+	       :  0 - Vendor Specific Class / unknown subclass / unknown protocol (ff/00/00)
+
+	    3-1: Logitech, Inc. : QuickCam Pro 4000 (046d:08b2)
+	       : /sys/devices/pci0000:00/0000:00:1e.0/0000:02:0a.0/usb3/3-1
+	       : (Defined at Interface level) / unknown subclass / unknown protocol (00/00/00)
+	       :  0 - Data / unknown subclass / unknown protocol (0a/ff/00)
+	       :  1 - Audio / Control Device / unknown protocol (01/01/00)
+	       :  2 - Audio / Streaming / unknown protocol (01/02/00)
+
+Attach a remote USB device:
+
+    deux:# usbip attach --remote 10.0.0.3 --busid 1-1
+    port 0 attached
+
+Show the devices attached to this client:
+
+    deux:# usbip port
+    Port 00: <Port in Use> at Full Speed(12Mbps)
+	   Prolific Technology, Inc. : unknown product (067b:3507)
+	   6-1 -> usbip://10.0.0.3:3240/1-1  (remote bus/dev 001/004)
+	   6-1:1.0 used by usb-storage
+			  /sys/class/scsi_device/0:0:0:0/device
+			  /sys/class/scsi_host/host0/device
+			  /sys/block/sda/device
+
+Detach the imported device:
+
+    deux:# usbip detach --port 0
+    port 0 detached
+
+
+[Checklist]
+    - usbip-host.ko must be bound to the target device.
+	- See /sys/kernel/debug/usb/devices and find "Driver=..." lines of the device.
+    - Target USB gadget must be bound to vudc
+      (using USB gadget susbsys, not usbip bind command)
+    - Shutdown firewall.
+	- usbip now uses TCP port 3240.
+    - Disable SELinux.
+    - Check the kernel and daemon messages.
+
+
+[Contact]
+    Mailing List: linux-usb@vger.kernel.org