Re: [PATCH 1/4] rust: bindings: add io_uring headers in bindings_helper.h

[kernel test robot <lkp@intel.com>]

Hi Sidong,

kernel test robot noticed the following build warnings:

[auto build test WARNING on rust/rust-next]
[also build test WARNING on char-misc/char-misc-testing char-misc/char-misc-next char-misc/char-misc-linus soc/for-next linus/master v6.16-rc6 next-20250718]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Sidong-Yang/rust-bindings-add-io_uring-headers-in-bindings_helper-h/20250719-223630
base:   https://github.com/Rust-for-Linux/linux rust-next
patch link:    https://lore.kernel.org/r/20250719143358.22363-2-sidong.yang%40furiosa.ai
patch subject: [PATCH 1/4] rust: bindings: add io_uring headers in bindings_helper.h
config: x86_64-rhel-9.4-rust (https://download.01.org/0day-ci/archive/20250720/202507202006.8ZnBwBsW-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
rustc: rustc 1.88.0 (6b00bc388 2025-06-23)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250720/202507202006.8ZnBwBsW-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202507202006.8ZnBwBsW-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> warning: `extern` fn uses type `io_tw_state`, which is not FFI-safe
   --> rust/bindings/bindings_generated.rs:109725:28
   |
   109725 |     ::core::option::Option<unsafe extern "C" fn(req: *mut io_kiocb, tw: io_tw_token_t)>;
   |                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
   |
   = help: consider adding a member to this struct
   = note: this struct has no fields
   note: the type is defined here
   --> rust/bindings/bindings_generated.rs:109642:1
   |
   109642 | pub struct io_tw_state {}
   | ^^^^^^^^^^^^^^^^^^^^^^
   = note: `#[warn(improper_ctypes_definitions)]` on by default

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