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b=mo/IZUZR87m061SONyuxATMj5nYLudVagEu+ohuxGe1qYvlMxID6PY0z/ymR7+YAg qDQ1LDn+6sQzmGQlUr0pfXgHsHICWQokyXr5160x+xA4B9AEiPAEF5NwH5UaBLw/9q xluSzp4LmUWWbqNOq+FofqZFoB7Z7fZ3Dtre46HG7CxOe8RqTbU+sL4+FtpQjsUWsi XtvL+GOQh4p7kBTw4nSsIHJMf2hAsQvmAAlXKEP14BWzmxogTSlk9EvdUIDdgs2Ih+ R5uN4hGPYcUiRuveRQVKqF6YdBtJkgjj232JSf6sPtAZav7pYKgj7kBOsR83D94ye6 aQ48JOwm5P3MA== Message-ID: <01106f43-3338-4eec-bd6b-2ee820f7267c@kernel.org> Date: Thu, 15 Aug 2024 14:17:41 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 13/26] rust: alloc: implement kernel `Vec` type To: Alice Ryhl Cc: ojeda@kernel.org, alex.gaynor@gmail.com, wedsonaf@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, benno.lossin@proton.me, a.hindborg@samsung.com, akpm@linux-foundation.org, daniel.almeida@collabora.com, faith.ekstrand@collabora.com, boris.brezillon@collabora.com, lina@asahilina.net, mcanal@igalia.com, zhiw@nvidia.com, cjia@nvidia.com, jhubbard@nvidia.com, airlied@redhat.com, ajanulgu@redhat.com, lyude@redhat.com, linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-mm@kvack.org References: <20240812182355.11641-1-dakr@kernel.org> <20240812182355.11641-14-dakr@kernel.org> From: Danilo Krummrich Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: 3441dfcq1srjpcw33nohy3w1isj1kszg X-Rspamd-Queue-Id: E80C11A0014 X-Rspamd-Server: rspam11 X-HE-Tag: 1723724269-673847 X-HE-Meta: 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 G98bS+AQ 6Cxd7VtG0Cg75dSYwDr3SHbPHHiRnP3LzppVCxu4u1PsN9Ho/+dFjE8iz5/7InielWfR5Yc2LIPrgf4KYcKc+3zTKyT9PX/nV1FF1IASgLTnELUUnif/0/Jy9VYBJlZNb4rd1O1H1h1BWczEAL85Shc0PlCp+XmlNMg1/lnCLGsL51dgU2ZT6hzmJEAP5+nv3MSh996/9TlBXuBT+ZXuxffEdi4j9F+soobf9T26MQ3FWw5tRM51rXyfrt5tGQ3yfTeRGffX0rNhLQif4NMWTCBI+bb4u+EzeGWsThr93hLNiu2F9d6iCVyM0tzHZMqpXtzPM/d6Feme+5n53WTOXVdMlJvccZcBLEWpgNPheVoOIyzumSMQWt21f5ZL9yy9OjTfsTKCRb4x/vlQiOUVXxmuu4zrzM4fAGnVNiUVM2q/CiYibNpAh9/zip/kbZesasQj9lOenFNJXTAkbGg4B2O6VkA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.006270, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/15/24 9:30 AM, Alice Ryhl wrote: > On Thu, Aug 15, 2024 at 12:46 AM Danilo Krummrich wrote: >> >> On Wed, Aug 14, 2024 at 10:42:28AM +0200, Alice Ryhl wrote: >>>> +#[macro_export] >>>> +macro_rules! kvec { >>>> + () => ( >>>> + { >>>> + $crate::alloc::KVec::new() >>>> + } >>>> + ); >>>> + ($elem:expr; $n:expr) => ( >>>> + { >>>> + $crate::alloc::KVec::from_elem($elem, $n, GFP_KERNEL) >>>> + } >>>> + ); >>>> + ($($x:expr),+ $(,)?) => ( >>>> + { >>>> + match $crate::alloc::KBox::new([$($x),+], GFP_KERNEL) { >>>> + Ok(b) => Ok($crate::alloc::KBox::into_vec(b)), >>>> + Err(e) => Err(e), >>> >>> Hmm. This currently generates code that: >>> >>> 1. Creates the array. >>> 2. Allocates the memory. >>> 3. Moves the array into the box. >>> >>> Whereas the stdlib macro swaps step 1 and 2. >> >> Isn't stdlib [1] doing the same thing I do? >> >> [1] https://doc.rust-lang.org/1.80.1/src/alloc/macros.rs.html#49 > > Stdlib is using something called #[rustc_box] which has the effect I described. > >>> You can do the same by utilizing new_uninit. A sketch: >>> >>> match KBox::<[_; _]>::new_uninit(GFP_KERNEL) { >> >> How do we get the size here? `#![feature(generic_arg_infer)]` seems to be >> unstable. > > It probably works if you don't specify the type at all: > `KBox::new_uninit`. But you should double check. That works, thanks. > >>> Ok(b) => Ok(KVec::from(KBox::write(b, [$($x),+]))), >>> Err(e) => Err(e), >>> } >