linux-kernel - Re: [PATCH v2 2/3] rust: clist: Add basic list infrastructure and head iterator

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <fc3553f1-ac3d-4af0-9b2e-dd440ad6d3eb@nvidia.com>
Date: Tue, 25 Nov 2025 18:03:58 -0500
From: Joel Fernandes <joelagnelf@...dia.com>
To: Alexandre Courbot <acourbot@...dia.com>, linux-kernel@...r.kernel.org,
 rust-for-linux@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 dakr@...nel.org, airlied@...il.com
Cc: apopple@...dia.com, ojeda@...nel.org, alex.gaynor@...il.com,
 boqun.feng@...il.com, gary@...yguo.net, bjorn3_gh@...tonmail.com,
 lossin@...nel.org, a.hindborg@...nel.org, aliceryhl@...gle.com,
 tmgross@...ch.edu, simona@...ll.ch, maarten.lankhorst@...ux.intel.com,
 mripard@...nel.org, tzimmermann@...e.de, jhubbard@...dia.com,
 ttabi@...dia.com, joel@...lfernandes.org, elle@...thered-steel.dev,
 daniel.almeida@...labora.com, arighi@...dia.com, phasta@...nel.org,
 nouveau@...ts.freedesktop.org,
 Nouveau <nouveau-bounces@...ts.freedesktop.org>
Subject: Re: [PATCH v2 2/3] rust: clist: Add basic list infrastructure and
 head iterator

Hi Alex,

(I agree with all the suggestions, I will reply to the ones where I have
comments in a few emails if that's Ok.).

Replied to one below:

On 11/23/2025 10:47 PM, Alexandre Courbot wrote:
>> +    }
>> +
>> +    /// Check if this node is linked in a list (not isolated).
>> +    #[inline]
>> +    pub fn is_in_list(&self) -> bool {
>> +        // SAFETY: self.as_raw() is valid per type invariants.
>> +        unsafe {
>> +            let raw = self.as_raw();
>> +            (*raw).next != raw && (*raw).prev != raw
>> +        }
>> +    }
>> +
>> +    /// Check if the list is empty.
>> +    #[inline]
>> +    pub fn is_empty(&self) -> bool {
>> +        // SAFETY: self.as_raw() is valid per type invariants.
>> +        unsafe {
>> +            let raw = self.as_raw();
>> +            (*raw).next == raw
>> +        }
>> +    }
>
> Does this method also apply to non-sentinel nodes? If not, should we
> move it to `Clist`?

Yes it does, will move it.

> 
> I am also wondering what the difference is with `is_in_list`. If
> `raw.next == raw`, then on a valid list `raw.prev == raw` as well, so
> it seems to be that `is_in_list()` is equivalent to `!is_empty()`.

Yes, this is a good thing for me to refactor. We can keep is_in_list() in
ClistHead and move ClistHead::Empty() to Clist. Though I would probably directly
compare the pointers instead of calling is_in_list() because it seems weird to
check with a sentinel list_head about whether it is in the list :) After all, it
IS the list :-D. I will rearrange it, thanks for the suggestion!

 - Joel