linux-kernel - Re: [PATCH v10 0/7] Rust Abstractions for PWM subsystem with TH1520 PWM driver

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: <4hmb3di5x2iei43nmrykrj5wzlltrf3vrnqvexiablonbscn57@4bbsz5c76t63>
Date: Thu, 10 Jul 2025 17:25:33 +0200
From: Uwe Kleine-König <ukleinek@...nel.org>
To: Michal Wilczynski <m.wilczynski@...sung.com>
Cc: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>, 
	Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, 
	Björn Roy Baron <bjorn3_gh@...tonmail.com>, Andreas Hindborg <a.hindborg@...nel.org>, 
	Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>, 
	Danilo Krummrich <dakr@...nel.org>, Guo Ren <guoren@...nel.org>, Fu Wei <wefu@...hat.com>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
	Conor Dooley <conor+dt@...nel.org>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Alexandre Ghiti <alex@...ti.fr>, Marek Szyprowski <m.szyprowski@...sung.com>, 
	Benno Lossin <lossin@...nel.org>, Michael Turquette <mturquette@...libre.com>, 
	Drew Fustini <fustini@...nel.org>, linux-kernel@...r.kernel.org, linux-pwm@...r.kernel.org, 
	rust-for-linux@...r.kernel.org, linux-riscv@...ts.infradead.org, devicetree@...r.kernel.org, 
	Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Subject: Re: [PATCH v10 0/7] Rust Abstractions for PWM subsystem with TH1520
 PWM driver

Hello Michal,

On Thu, Jul 10, 2025 at 03:48:08PM +0200, Michal Wilczynski wrote:
> On 7/10/25 15:10, Uwe Kleine-König wrote:
> > On Thu, Jul 10, 2025 at 10:42:07AM +0200, Michal Wilczynski wrote:
> >> On 7/7/25 11:48, Michal Wilczynski wrote:
> >>> The series is structured as follows:
> >>>  - Expose static function pwmchip_release.
> > 
> > Is this really necessary? I didn't try to understand the requirements
> > yet, but I wonder about that. If you get the pwmchip from
> > __pwmchip_add() the right thing to do to release it is to call
> > pwmchip_remove(). Feels like a layer violation.
> 
> It's required to prevent a memory leak in a specific, critical failure
> scenario. The sequence of events is as follows:
> 
>     pwm::Chip::new() succeeds, allocating both the C struct pwm_chip and
>     the Rust drvdata.
> 
>     pwm::Registration::register() (which calls pwmchip_add()) fails for
>     some reason.

If you called pwmchip_alloc() but not yet pwmchip_add(), the right
function to call for cleanup is pwmchip_put().

>     The ARef<Chip> returned by new() is dropped, its reference count
>     goes to zero, and our custom release_callback is called.
> 
> [...]
> >>> ---
> >>> base-commit: 47753b5a1696283930a78aae79b29371f96f5bca
> > 
> > I have problems applying this series and don't have this base commit in
> > my repo.
> 
> Sorry for the confusion. Base commit doesn't exist in the mainline
> kernel or linux-next, cause I've added some dependecies for compilation,
> like IoMem for the driver (uploaded full branch on github [1]). The
> bindings however doesn't depend on anything that's not in linux-next.

The series didn't apply to my pwm/for-next branch.

Note that the base-commit should always be a publically known commit.
See the chapter about "Base Tree Information" in git-format-patch(1).

Best regards
Uwe

Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)