Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Sat, 15 Jul 2023 15:27:12 +0100
From:   Gary Guo <gary@garyguo.net>
To:     Asahi Lina <lina@asahilina.net>
Cc:     Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Boqun Feng <boqun.feng@gmail.com>,
        =?UTF-8?B?QmrDtnJu?= Roy Baron <bjorn3_gh@protonmail.com>,
        Benno Lossin <benno.lossin@proton.me>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nicolas Schier <nicolas@fjasle.eu>, Tom Rix <trix@redhat.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Hector Martin <marcan@marcan.st>,
        Sven Peter <sven@svenpeter.dev>,
        Alyssa Rosenzweig <alyssa@rosenzweig.io>,
        asahi@lists.linux.dev, rust-for-linux@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
        llvm@lists.linux.dev
Subject: Re: [PATCH RFC 01/11] rust: types: Add Opaque::zeroed()
Message-ID: <20230715152712.21008d5a.gary@garyguo.net>
In-Reply-To: <20230714-classless_lockdep-v1-1-229b9671ce31@asahilina.net>
References: <20230714-classless_lockdep-v1-0-229b9671ce31@asahilina.net>
        <20230714-classless_lockdep-v1-1-229b9671ce31@asahilina.net>
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?UtIplAQ8YfRrJukoqvtGDlFl41v6op5Py+FzDazaioiVeVkAhqdbBz9Zc96l?=
 =?us-ascii?Q?VGD46WCKCHm7d0z/0s+BlNTQJkp31gvEsWzqmHWbkOcTwn3FVAOIDgFN4Joh?=
 =?us-ascii?Q?uU7Lvm7ZHfe+/ojSVjfPRcTgE6ZqqDqvhefdyAoCfKtZNwmlgoWL9csdHonL?=
 =?us-ascii?Q?Q6DHtWRh5ssaYVoZpBLWnmiHegQuiEhD+WrRkZnopOOLR7pko7iApNOfBmcb?=
 =?us-ascii?Q?Gs/CcLrVMKyExFZnN1XuowpPkrt1Fck5AFZT2r8DOsVo+xD6cvXOFsNLHhQz?=
 =?us-ascii?Q?uWVpEzGyGsYa+IU8AnmurP7B2bQ/9FWN2DivDhSY3wYD7h5iOXQKwhHh4WUS?=
 =?us-ascii?Q?TNNfQ6G3RxSS7k9HoMyUFB9kw1+5BFc5dmhbtOFVvrikumDAUH/OhaBr3OTH?=
 =?us-ascii?Q?a2inm5PVKU3IyUCJ5VffQcMPA6v7OW38Gp8kfDGvI5+TGbS1KjlGRPWc1LN5?=
 =?us-ascii?Q?yT55SUCubdmPOin5w0vU4KwynkZQLUDOE3Ai08qBHX7A6WXbjpfYOCaJ4WEH?=
 =?us-ascii?Q?obCp2i0EpjVTBWy8AsJ9nESX1AJwsRHa7Jm6S2XyrvZCJpCvZK6VLtjSwKj9?=
 =?us-ascii?Q?BVciMiBpZqAfjZ0Om6chQFsnZgg1CkX6j6jAuHP/kFKwpr+lIomAV8ehwYfn?=
 =?us-ascii?Q?mXnZ2EOIIxbZ+svVarHZRVeOhnxnkQPFXA3kTeJTVpJKn98wOgFvv12XGfX/?=
 =?us-ascii?Q?/B4SBWzKZd/c1z9IjYd17VnknXgGTIwP5r/GS19JxPQeNXFnkVdgUdGsNGs4?=
 =?us-ascii?Q?DZ9UCtc1BuiRnqn3sb07Kro9C3rH5vrJqD03DVhPYmxcMeP7qn9tTEiVyOK5?=
 =?us-ascii?Q?kTLGC6cNkOsQiB3m+TJe3YN+X13Yl3m5h1PMbr4HkCdcfeL2m9hWVZ4max8/?=
 =?us-ascii?Q?vXfR1vy1ANzcorKERYKpxZGo3tp4MvVMjuFZM3KOKieakjmaIYVtXPvk+zH/?=
 =?us-ascii?Q?mL+Imz27jvpJ9zMu8UDc4AAxIfbdUr5nT1DbwcURU1KkD7As7uQY8D/ZgfwU?=
 =?us-ascii?Q?XEn3TBBmIX3yYSVx6C14yqxzJHy1Vu70UjOEz1Xvv8DKyzOp9FsUmufM+1KD?=
 =?us-ascii?Q?jFR3d840tTIA7IZk9PzrokvV69vBeUpQrBVcHUCBWKS71y4hyosF3GE94FSR?=
 =?us-ascii?Q?5aXhNp+mru/pKM9/kTGYaN8tf1BYqWCgtpAMjkkSubRavFshJShtrwdQsNBc?=
 =?us-ascii?Q?cc6lCNt9nBarq/MFYTYMHBk64plogvfQWWMAszJ3Kz5o6eKi7564cWnC5I+o?=
 =?us-ascii?Q?znRJPp2e8PiDnxEjnHot69DihO1v9WGx/k4QOhEBjzbZ1s7zPUE8sdby8OtG?=
 =?us-ascii?Q?VNYWvQVtT3v61ZOIGHqe5C7PQ4h2hNPDOpiG+dNvyAl/FVZHDxNTZg9KXj3N?=
 =?us-ascii?Q?9STyq/wOkq3+y+nnVuQmaZKquIdqnKu0Dkt8HS3Em/c5XxmzdvbMP/GFR5Cx?=
 =?us-ascii?Q?IFsDUsqcg65nPhBql0H6catM5GQUxHxV5P/WbbIqb/EFqI2zJTvPbgHlhQgr?=
 =?us-ascii?Q?t85VfaAkXT8Vgxo8sr0SxHa7tk1qZxWKCCkVsCIm7g3Cn3n/ZrDY5YGeOXzd?=
 =?us-ascii?Q?wDmxnnBCV6VH3G+nAAGR4LyUXP0EP651oAmQi1Sf?=
X-OriginatorOrg: garyguo.net
X-MS-Exchange-CrossTenant-Network-Message-Id: 73a16099-ae40-48c3-b01f-08db853f95af
X-MS-Exchange-CrossTenant-AuthSource: LO2P265MB5183.GBRP265.PROD.OUTLOOK.COM
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Jul 2023 14:27:14.4966
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: bbc898ad-b10f-4e10-8552-d9377b823d45
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: b2h8fo1qQTU/22yVy84huZY/WI3G+1K63IyO2ObcfJ7Aka/1tk2C4MSXRRcjNVQEfU/mAT9/zw0yZwI6doTo2w==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: LO3P265MB1786
X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_BLOCKED,
        RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE,
        URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, 14 Jul 2023 18:13:53 +0900
Asahi Lina <lina@asahilina.net> wrote:

> Opaque types are internally MaybeUninit, so it's safe to actually
> zero-initialize them as long as we don't claim they are initialized.
> This is useful for many FFI types that are expected to be zero-inited by
> the user.
> 
> Signed-off-by: Asahi Lina <lina@asahilina.net>

Reviewed-by: Gary Guo <gary@garyguo.net>

I agree with Alice that this patch can accepted on its own.

> ---
>  rust/kernel/types.rs | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
> index 1e5380b16ed5..185d3493857e 100644
> --- a/rust/kernel/types.rs
> +++ b/rust/kernel/types.rs
> @@ -237,6 +237,11 @@ pub const fn uninit() -> Self {
>          Self(MaybeUninit::uninit())
>      }
>  
> +    /// Creates a zeroed value.
> +    pub fn zeroed() -> Self {
> +        Self(MaybeUninit::zeroed())
> +    }
> +
>      /// Creates a pin-initializer from the given initializer closure.
>      ///
>      /// The returned initializer calls the given closure with the pointer to the inner `T` of this
>