On Tue, Mar 07, 2023 at 11:25:27PM +0900, Asahi Lina wrote: [...]
+// SAFETY: `Device` only holds a pointer to a C device, which is safe to be used from any thread. +unsafe impl<T: drm::drv::Driver> Send for Device<T> {}
+// SAFETY: `Device` only holds a pointer to a C device, references to which are safe to be used +// from any thread. +unsafe impl<T: drm::drv::Driver> Sync for Device<T> {}
Here is the mind model I use to check whether a type is `Send` or `Sync`
* If an object of a type can be created on one thread and dropped on the another thread, then it's `Send`.
* If multiple threads can call the immutable functions (i.e. functions with `&self`) of the same object of a type, then the it's `Sync`.
Maybe it's incomplete, but at least I find it useful to determine whether a type is `Send` or `Sync`: it's not just the struct representation, the behaviors (functions) of the struct also matter.
If that looks reasonable to you, maybe update the "SAFETY" comments in the future version? Thanks ;-)
(I know you brought this up in the meeting, sorry I guess I wasn't fully woken when answering you ;-))
Regards, Boqun
+// Make drm::Device work for dev_info!() and friends +unsafe impl<T: drm::drv::Driver> device::RawDevice for Device<T> {
- fn raw_device(&self) -> *mut bindings::device {
// SAFETY: ptr must be valid per the type invariantunsafe { (*self.ptr).dev }- }
+}
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