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bh=2sSsIzdACzoPnqvUhervrAOknVeczgrx1816hyZSkw4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fRSbsK68TywYDweAzJmxnLHP52gywwuHTd3U0HBB6jz5L0XkmeuGK4tHtivRhzfHJ jA/tut0+mI3ZgS9I32hAcnIeJrDvWZXp5isJ+RWfbfvPkN32+uBawoWrYL5nou+Blx zdERRBRrfBllOMd5yv5grsEB8zrKexPjR5CqqIyHs7l2pwgJoe+dj7z+IHiIckZ4B7 3qmwiwXJ/Wztcs0M/fjlblqz/vkLqkD+leaiAjL8U625qPXa6hk8QJWo+9ZwzMPSuj CGPuU/nWAZqCth6223YP+dYTee+RT/rQb7ZPVKcaijxzCLHRAkVEolLhArocmgLuTg Fc9D2RN9mHdVA== From: Danilo Krummrich To: 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, aliceryhl@google.com, akpm@linux-foundation.org Cc: 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, Danilo Krummrich Subject: [PATCH v9 17/29] rust: alloc: implement `IntoIterator` for `Vec` Date: Fri, 4 Oct 2024 17:41:21 +0200 Message-ID: <20241004154149.93856-18-dakr@kernel.org> X-Mailer: git-send-email 2.46.1 In-Reply-To: <20241004154149.93856-1-dakr@kernel.org> References: <20241004154149.93856-1-dakr@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: ghgjfz7p4afiuawfwcjq4k5bb67h7acz X-Rspamd-Queue-Id: 27E091C001F X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1728056618-267329 X-HE-Meta: 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 6bEEcBBp 1H0EC0n0OrHzAoEHy93R2re6qaYnLFrXZULvzVQF3bvU4dHeDEUUiTUy12ZMezG8rfqJ2LxEJ5IGdftO6H+b3H6x4h5UfnlG7uOfa5U7aRP3laFh69/yWgnObUn57DNmAG4m6ADW9dni9wXzARiAXJMsM5CeRozexh9RBxr+6G5REvUhzXRu1gPHZHAbFIdfnn2Jtgf6z2NC3yw3oMbrpgvgSvwaA7j3QHlgJrUnMVuKAUldOuZPDs/NK42F+FFkxRY2Kx825fpq0v1D4u1/bMuNBiMyVR2yjSPJAfnrzOOs6tOs4sU+neAhdG/ZfLr7ausSTB+PpcFX45kwuQlQA2NZZhpHCYgjb5QrsaWmiKJN2ZbtwrjOMsedlwZj5jNPytD+j X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Implement `IntoIterator` for `Vec`, `Vec`'s `IntoIter` type, as well as `Iterator` for `IntoIter`. `Vec::into_iter` disassembles the `Vec` into its raw parts; additionally, `IntoIter` keeps track of a separate pointer, which is incremented correspondingsly as the iterator advances, while the length, or the count of elements, is decremented. This also means that `IntoIter` takes the ownership of the backing buffer and is responsible to drop the remaining elements and free the backing buffer, if it's dropped. Reviewed-by: Alice Ryhl Reviewed-by: Benno Lossin Reviewed-by: Gary Guo Signed-off-by: Danilo Krummrich --- rust/kernel/alloc.rs | 1 + rust/kernel/alloc/kvec.rs | 170 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 171 insertions(+) diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs index 961070daf6db..1d57bfe2acb1 100644 --- a/rust/kernel/alloc.rs +++ b/rust/kernel/alloc.rs @@ -20,6 +20,7 @@ pub use self::kbox::KVBox; pub use self::kbox::VBox; +pub use self::kvec::IntoIter; pub use self::kvec::KVVec; pub use self::kvec::KVec; pub use self::kvec::VVec; diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index d41353b7653d..86382827f576 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -648,3 +648,173 @@ fn eq(&self, other: &$rhs) -> bool { self[..] == other[..] } [A: Allocator, const N: usize] Vec, [U; N], [A: Allocator, const N: usize] Vec, &[U; N], } + +impl<'a, T, A> IntoIterator for &'a Vec +where + A: Allocator, +{ + type Item = &'a T; + type IntoIter = slice::Iter<'a, T>; + + fn into_iter(self) -> Self::IntoIter { + self.iter() + } +} + +impl<'a, T, A: Allocator> IntoIterator for &'a mut Vec +where + A: Allocator, +{ + type Item = &'a mut T; + type IntoIter = slice::IterMut<'a, T>; + + fn into_iter(self) -> Self::IntoIter { + self.iter_mut() + } +} + +/// An [`Iterator`] implementation for [`Vec`] that moves elements out of a vector. +/// +/// This structure is created by the [`Vec::into_iter`] method on [`Vec`] (provided by the +/// [`IntoIterator`] trait). +/// +/// # Examples +/// +/// ``` +/// let v = kernel::kvec![0, 1, 2]?; +/// let iter = v.into_iter(); +/// +/// # Ok::<(), Error>(()) +/// ``` +pub struct IntoIter { + ptr: *mut T, + buf: NonNull, + len: usize, + layout: ArrayLayout, + _p: PhantomData, +} + +impl Iterator for IntoIter +where + A: Allocator, +{ + type Item = T; + + /// # Examples + /// + /// ``` + /// let v = kernel::kvec![1, 2, 3]?; + /// let mut it = v.into_iter(); + /// + /// assert_eq!(it.next(), Some(1)); + /// assert_eq!(it.next(), Some(2)); + /// assert_eq!(it.next(), Some(3)); + /// assert_eq!(it.next(), None); + /// + /// # Ok::<(), Error>(()) + /// ``` + fn next(&mut self) -> Option { + if self.len == 0 { + return None; + } + + let current = self.ptr; + + // SAFETY: We can't overflow; decreasing `self.len` by one every time we advance `self.ptr` + // by one guarantees that. + unsafe { self.ptr = self.ptr.add(1) }; + + self.len -= 1; + + // SAFETY: `current` is guaranteed to point at a valid element within the buffer. + Some(unsafe { current.read() }) + } + + /// # Examples + /// + /// ``` + /// let v: KVec = kernel::kvec![1, 2, 3]?; + /// let mut iter = v.into_iter(); + /// let size = iter.size_hint().0; + /// + /// iter.next(); + /// assert_eq!(iter.size_hint().0, size - 1); + /// + /// iter.next(); + /// assert_eq!(iter.size_hint().0, size - 2); + /// + /// iter.next(); + /// assert_eq!(iter.size_hint().0, size - 3); + /// + /// # Ok::<(), Error>(()) + /// ``` + fn size_hint(&self) -> (usize, Option) { + (self.len, Some(self.len)) + } +} + +impl Drop for IntoIter +where + A: Allocator, +{ + fn drop(&mut self) { + // SAFETY: `self.ptr` is guaranteed to be valid by the type invariant. + unsafe { ptr::drop_in_place(ptr::slice_from_raw_parts_mut(self.ptr, self.len)) }; + + // SAFETY: + // - `self.buf` was previously allocated with `A`. + // - `self.layout` matches the `ArrayLayout` of the preceeding allocation. + unsafe { A::free(self.buf.cast(), self.layout.into()) }; + } +} + +impl IntoIterator for Vec +where + A: Allocator, +{ + type Item = T; + type IntoIter = IntoIter; + + /// Consumes the `Vec` and creates an `Iterator`, which moves each value out of the + /// vector (from start to end). + /// + /// # Examples + /// + /// ``` + /// let v = kernel::kvec![1, 2]?; + /// let mut v_iter = v.into_iter(); + /// + /// let first_element: Option = v_iter.next(); + /// + /// assert_eq!(first_element, Some(1)); + /// assert_eq!(v_iter.next(), Some(2)); + /// assert_eq!(v_iter.next(), None); + /// + /// # Ok::<(), Error>(()) + /// ``` + /// + /// ``` + /// let v = kernel::kvec![]; + /// let mut v_iter = v.into_iter(); + /// + /// let first_element: Option = v_iter.next(); + /// + /// assert_eq!(first_element, None); + /// + /// # Ok::<(), Error>(()) + /// ``` + #[inline] + fn into_iter(self) -> Self::IntoIter { + let buf = self.ptr; + let layout = self.layout; + let (ptr, len, _) = self.into_raw_parts(); + + IntoIter { + ptr, + buf, + len, + layout, + _p: PhantomData::, + } + } +} -- 2.46.1