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b=PKbvnFq69EFAhB6pU5+2+oAbesuU7VfjBQCW1kVBwk9ertWekxmuinZpOP2NcCiRc zB3eQj6ya17dYeu8WrFA2yb5bP27PP8WonU6xAjUhTAkXrH0fq+jmGj0J/9XXvowSd fUpf5T0ONumN7xqtFoxqu3DVtr1Z8/fuNBuuXUBCXMmcdd1Jiesbc0f1ykEEEaSTBL A77jMHZrHShIfty+LHRGK22oUg6y6qyMXxXtWSJlGY/3fbDl+Sdt7IF98XErOQ6QJt 3vLOZu942+URWPenXjjBXm7hd9Tqui2RFBqSSevatSdI4itDkeoFL9IFafXKZefOJw Yzt+7GCqoO58A== Date: Thu, 15 Aug 2024 00:46:41 +0200 From: Danilo Krummrich 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 Subject: Re: [PATCH v5 13/26] rust: alloc: implement kernel `Vec` type Message-ID: References: <20240812182355.11641-1-dakr@kernel.org> <20240812182355.11641-14-dakr@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 0374E180017 X-Stat-Signature: 7otbkdypwmr3jqo3xxmmayob1ns3qpjj X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1723675610-850007 X-HE-Meta: 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 ei+WXRqT SBTH/PQcUtudXR6Xug6ci99NSHci6D5Mqg8NsCdP3ggCPhUAm8/8lfqOv6lW44Gi3MpH7VdBdztA4AeIYKbl2YLafhu4kb9zhKPH3PG6yNPL/T7/EY+psKbk9agDAQV3OMBh3C+kfQ5pkmMInF1TbR1oypP2zDu/FQdMAig3bv3F6xDPEujseTJHIqaoSsOICS7A+yGJ6V855IR4FTe3Dnx4QNbhAOep/FecIyP9pb0Mmw5ubBv9v7xXMN4jHQf/dvDFOqeL0XCHEhS4o7oAfAFw5jpfRX+ai3nZxk7Q29SoANkyEVjE0ySve+nYW1DzRqZwqgvfi6+5RqSzu2EHpMTGJUs7wL742XtVlpn1YEziydKZhEoFnjvBvig== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000346, 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 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 > 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. > Ok(b) => Ok(KVec::from(KBox::write(b, [$($x),+]))), > Err(e) => Err(e), > }