Re: [PATCH v2 2/2] rust: miscdevice: add base miscdevice abstraction

[Alice Ryhl]

On Wed, Oct 2, 2024 at 4:06 PM Christian Brauner <brauner@xxxxxxxxxx> wrote:
>
> On Tue, Oct 01, 2024 at 08:22:22AM GMT, Alice Ryhl wrote:
> > +unsafe extern "C" fn fops_open<T: MiscDevice>(
> > +    inode: *mut bindings::inode,
> > +    file: *mut bindings::file,
> > +) -> c_int {
> > +    // SAFETY: The pointers are valid and for a file being opened.
> > +    let ret = unsafe { bindings::generic_file_open(inode, file) };
> > +    if ret != 0 {
> > +        return ret;
> > +    }
>
> Do you have code where that function is used? Because this looks wrong
> or at least I don't understand from just a glance whether that
> generic_file_open() call makes sense.
>
> Illustrating how we get from opening /dev/binder to this call would
> help.

Hmm. I wrote this by comparing with the ashmem open callback. Now that
you mention it you are right that Binder does not call
generic_file_open ... I have to admit that I don't know what
generic_file_open does.

Alice