On Fri Jul 11, 2025 at 9:33 PM CEST, Danilo Krummrich wrote:
> On Fri Jul 11, 2025 at 8:30 PM CEST, Benno Lossin wrote:
>> On Fri Jul 11, 2025 at 5:02 PM CEST, Danilo Krummrich wrote:
>>> On Thu Jul 10, 2025 at 10:01 AM CEST, Benno Lossin wrote:
>>>> On Thu Jul 10, 2025 at 4:24 AM CEST, Alistair Popple wrote:
>>>>> diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
>>>>> index 8435f8132e38..5c35a66a5251 100644
>>>>> --- a/rust/kernel/pci.rs
>>>>> +++ b/rust/kernel/pci.rs
>>>>> @@ -371,14 +371,18 @@ fn as_raw(&self) -> *mut bindings::pci_dev {
>>>>>
>>>>> impl Device {
>>>>> /// Returns the PCI vendor ID.
>>>>> + #[inline]
>>>>> pub fn vendor_id(&self) -> u16 {
>>>>> - // SAFETY: `self.as_raw` is a valid pointer to a `struct pci_dev`.
>>>>> + // SAFETY: by its type invariant `self.as_raw` is always a valid pointer to a
>>>>
>>>> s/by its type invariant/by the type invariants of `Self`,/
>>>> s/always//
>>>>
>>>> Also, which invariant does this refer to? The only one that I can see
>>>> is:
>>>>
>>>> /// A [`Device`] instance represents a valid `struct device` created by the C portion of the kernel.
>>>>
>>>> And this doesn't say anything about the validity of `self.as_raw()`...
>>>
>>> Hm...why not? If an instance of Self always represents a valid struct pci_dev,
>>> then consequently self.as_raw() can only be a valid pointer to a struct pci_dev,
>>> no?
>>
>> While it's true, you need to look into the implementation of `as_raw`.
>> It could very well return a null pointer...
>>
>> This is where we can use a `Guarantee` on that function. But since it's
>> not shorter than `.0.get()`, I would just remove it.
>
> We have 15 to 20 as_raw() methods of this kind in the tree. If this really needs
> a `Guarantee` to be clean, we should probably fix it up in a treewide change.
>
> as_raw() is a common pattern and everyone knows what it does, `.0.get()` seems
> much less obvious.
Yeah I guess then we need to do the treewide change... I don't have the
bandwidth for that, we can probably make this a good-first-issue.
---
Cheers,
Benno
