From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops 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 --- Documentation/usb/functionfs-desc.rst | 39 +++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) create mode 100644 Documentation/usb/functionfs-desc.rst (limited to 'Documentation/usb/functionfs-desc.rst') diff --git a/Documentation/usb/functionfs-desc.rst b/Documentation/usb/functionfs-desc.rst new file mode 100644 index 000000000..39649774d --- /dev/null +++ b/Documentation/usb/functionfs-desc.rst @@ -0,0 +1,39 @@ +====================== +FunctionFS Descriptors +====================== + +Some of the descriptors that can be written to the FFS gadget are +described below. Device and configuration descriptors are handled +by the composite gadget and are not written by the user to the +FFS gadget. + +Descriptors are written to the "ep0" file in the FFS gadget +following the descriptor header. + +.. kernel-doc:: include/uapi/linux/usb/functionfs.h + :doc: descriptors + +Interface Descriptors +--------------------- + +Standard USB interface descriptors may be written. The class/subclass of the +most recent interface descriptor determines what type of class-specific +descriptors are accepted. + +Class-Specific Descriptors +-------------------------- + +Class-specific descriptors are accepted only for the class/subclass of the +most recent interface descriptor. The following are some of the +class-specific descriptors that are supported. + +DFU Functional Descriptor +~~~~~~~~~~~~~~~~~~~~~~~~~ + +When the interface class is USB_CLASS_APP_SPEC and the interface subclass +is USB_SUBCLASS_DFU, a DFU functional descriptor can be provided. +The DFU functional descriptor is a described in the USB specification for +Device Firmware Upgrade (DFU), version 1.1 as of this writing. + +.. kernel-doc:: include/uapi/linux/usb/functionfs.h + :doc: usb_dfu_functional_descriptor -- cgit v1.3.1