linux-kernel - Re: [PATCH v3 07/16] rust: add `Revocable` type

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 for Android: free password hash cracker in your pocket

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

Message-ID: <CAH5fLgjgvq40mEsFZZLGi1s_OHNBsOXPT1Si6vM2sruM=tibQg@mail.gmail.com>
Date: Tue, 3 Dec 2024 10:24:16 +0100
From: Alice Ryhl <aliceryhl@...gle.com>
To: Danilo Krummrich <dakr@...nel.org>
Cc: gregkh@...uxfoundation.org, rafael@...nel.org, bhelgaas@...gle.com, 
	ojeda@...nel.org, alex.gaynor@...il.com, boqun.feng@...il.com, 
	gary@...yguo.net, bjorn3_gh@...tonmail.com, benno.lossin@...ton.me, 
	tmgross@...ch.edu, a.hindborg@...sung.com, airlied@...il.com, 
	fujita.tomonori@...il.com, lina@...hilina.net, pstanner@...hat.com, 
	ajanulgu@...hat.com, lyude@...hat.com, robh@...nel.org, 
	daniel.almeida@...labora.com, saravanak@...gle.com, 
	rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-pci@...r.kernel.org, devicetree@...r.kernel.org, 
	Wedson Almeida Filho <wedsonaf@...il.com>
Subject: Re: [PATCH v3 07/16] rust: add `Revocable` type

On Tue, Dec 3, 2024 at 10:21 AM Danilo Krummrich <dakr@...nel.org> wrote:
>
> On 10/29/24 2:26 PM, Alice Ryhl wrote:
> > On Tue, Oct 22, 2024 at 11:33 PM Danilo Krummrich <dakr@...nel.org> wrote:
> >> +/// A guard that allows access to a revocable object and keeps it alive.
> >> +///
> >> +/// CPUs may not sleep while holding on to [`RevocableGuard`] because it's in atomic context
> >> +/// holding the RCU read-side lock.
> >> +///
> >> +/// # Invariants
> >> +///
> >> +/// The RCU read-side lock is held while the guard is alive.
> >> +pub struct RevocableGuard<'a, T> {
> >> +    data_ref: *const T,
> >> +    _rcu_guard: rcu::Guard,
> >> +    _p: PhantomData<&'a ()>,
> >> +}
> >
> > Is this needed? Can't all users just use `try_access_with_guard`?
>
> Without this guard, how to we access `T` with just the `rcu::Guard`?

I don't think `try_access_with_guard` provides any access that you
can't get by doing `try_access_with_guard`.

That said, I guess this guard functions as a convenience accessors, so
I don't mind it.

Alice