On 02.04.24 00:17, Boqun Feng wrote:
On Mon, Apr 01, 2024 at 10:01:34PM +0000, Benno Lossin wrote:
On 01.04.24 23:10, Boqun Feng wrote:
On Mon, Apr 01, 2024 at 06:52:50PM +0000, Benno Lossin wrote: [...]
// Double nested modules, since then nobody can access the public items inside.mod __module_init {{mod __module_init {{use super::super::{type_};/// The \"Rust loadable module\" mark.//// This may be best done another way later on, e.g. as a new modinfo// key or a new section. For the moment, keep it simple.#[cfg(MODULE)]#[doc(hidden)]#[used]static __IS_RUST_MODULE: () = ();static mut __MOD: Option<{type_}> = None;// SAFETY: `__this_module` is constructed by the kernel at load time and will not be// freed until the module is unloaded.#[cfg(MODULE)]static THIS_MODULE: kernel::ThisModule = unsafe {{kernel::ThisModule::from_ptr(&kernel::bindings::__this_module as *const _ as *mut _)While we're at it, probably we want the following as well? I.e. using `Opaque` and extern block, because __this_module is certainly something interior mutable and !Unpin.
diff --git a/rust/macros/module.rs b/rust/macros/module.rs index 293beca0a583..8aa4eed6578c 100644 --- a/rust/macros/module.rs +++ b/rust/macros/module.rs @@ -219,7 +219,11 @@ mod __module_init {{ // freed until the module is unloaded. #[cfg(MODULE)] static THIS_MODULE: kernel::ThisModule = unsafe {{
kernel::ThisModule::from_ptr(&kernel::bindings::__this_module as *const _ as *mut _)
extern \"C\" {{static __this_module: kernel::types::Opaque<kernel::bindings::module>;}}kernel::ThisModule::from_ptr(__this_module.get()) }}; #[cfg(not(MODULE))] static THIS_MODULE: kernel::ThisModule = unsafe {{Thoughts?
I am not sure we need it. Bindgen generates
extern "C" { pub static mut __this_module: module; }And the `mut` should take care of the "it might be modified by other threads".
Hmm.. but there could a C thread modifies some field of __this_module while Rust code uses it, e.g. struct module has a list_head in it, which could be used by C code to put another module next to it.
This still should not be a problem, since we never actually read or write to the mutable static. The only thing we are doing is taking its address. `addr_of_mut!` should be sufficient. (AFAIK `static mut` is designed such that it can be mutated at any time by any thread. Maybe Gary knows more?)