From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout02.posteo.de (mout02.posteo.de [185.67.36.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 36C292C0F79 for ; Wed, 8 Oct 2025 18:10:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.67.36.66 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759947057; cv=none; b=uj7/Jta3U03CJrWnt5donZGoINudhJPSxD6fxZDtP44GOFAU9ssoVQ/renIZC89Jhyq6tZCZqwv/v+NJyn8Jt1+xjuxFEy8m0MgiLyZX+6sKW2o/NWu79+oHdjWreetHU/imE2jZoRTTHAmP0RnAXsGbJbsN8mwB8RFup8NDO3s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759947057; c=relaxed/simple; bh=9wHa2NsXWAKtyAdOkdyrbMj3P5LT1P+0xBazNJQx9Q8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hoiXyMyIOYQs/wN7O86LgLp1PoNErULcA8yEKgQHP8FSo35nnQq7XwOvv2aBU+8kLBBHEjhlca9k+NA6yI69bAbvKnQzQRO857MwzluK3Ikk6Y/QdQmCP5DrXpcSCdO5CcSxY88XmZK68ktsdJnjmJ1b/qmg/jU5jGX0jVWoSsk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=posteo.de; spf=pass smtp.mailfrom=posteo.de; dkim=pass (2048-bit key) header.d=posteo.de header.i=@posteo.de header.b=gM1ENKSE; arc=none smtp.client-ip=185.67.36.66 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=posteo.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=posteo.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=posteo.de header.i=@posteo.de header.b="gM1ENKSE" Received: from submission (posteo.de [185.67.36.169]) by mout02.posteo.de (Postfix) with ESMTPS id 7376F240105 for ; Wed, 8 Oct 2025 20:10:48 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=posteo.de; s=2017; t=1759947048; bh=XNe1KPk/bBREo5nDOhlFMfiW54nPpt8QW+L/MjqxhEw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version: Content-Transfer-Encoding:Autocrypt:OpenPGP:From; b=gM1ENKSEHQ/vfUp0cRLc1IO+g2TwjGuAMyu7fEZ6rsz+3VPaKHVPuC7sA9/g3DQ5Y Neeql1f/bBOSaGm12OiMx0viiQ2vhYPy1g0leIe/si4D72lrkzMNuV9ZfCGTI4ntmG Czc6Aj/S7cGGhYnvDWvkhWhGdB1tRCXXrCGObFg8uiCCWzRlwE/CMelJQdfn+1nfyV lNrGwJQvoRJ3FCxX/UFwYsg2S02JTlIxolrUDyUcvzGD0wms7wIjOlCB+DV7qhrrOI 6URMBzpJ3kNURVuTzlRdJSe8VVqgADNkmFlaiIufEygoy1hYo7eq2GWIxblmYZDxej 3JaZCr0vuimuQ== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4chgzR65yxz9rxS; Wed, 8 Oct 2025 20:10:43 +0200 (CEST) From: Markus Probst To: Lee Jones , Pavel Machek , Danilo Krummrich , Miguel Ojeda , Alex Gaynor , Igor Korotin Cc: Markus Probst , Lorenzo Stoakes , Vlastimil Babka , "Liam R. Howlett" , Uladzislau Rezki , Boqun Feng , Gary Guo , bjorn3_gh@protonmail.com, Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Daniel Almeida , linux-leds@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/4] rust: add pinned wrapper of Vec Date: Wed, 08 Oct 2025 18:10:45 +0000 Message-ID: <20251008181027.662616-3-markus.probst@posteo.de> In-Reply-To: <20251008181027.662616-2-markus.probst@posteo.de> References: <20251008181027.662616-1-markus.probst@posteo.de> <20251008181027.662616-2-markus.probst@posteo.de> Precedence: bulk X-Mailing-List: linux-leds@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Autocrypt: addr=markus.probst@posteo.de; prefer-encrypt=mutual; keydata=xsFNBGiDvXgBEADAXUceKafpl46S35UmDh2wRvvx+UfZbcTjeQOlSwKP7YVJ4JOZrVs93qReNLkO WguIqPBxR9blQ4nyYrqSCV+MMw/3ifyXIm6Pw2YRUDg+WTEOjTixRCoWDgUj1nOsvJ9tVAm76Ww+ /pAnepVRafMID0rqEfD9oGv1YrfpeFJhyE2zUw3SyyNLIKWD6QeLRhKQRbSnsXhGLFBXCqt9k5JA RhgQof9zvztcCVlT5KVvuyfC4H+HzeGmu9201BVyihJwKdcKPq+n/aY5FUVxNTgtI9f8wIbmfAja oT1pjXSp+dszakA98fhONM98pOq723o/1ZGMZukyXFfsDGtA3BB79HoopHKujLGWAGskzClwTjRQ xBqxh/U/lL1pc+0xPWikTNCmtziCOvv0KA0arDOMQlyFvImzX6oGVgE4ksKQYbMZ3Ikw6L1Rv1J+ FvN0aNwOKgL2ztBRYscUGcQvA0Zo1fGCAn/BLEJvQYShWKeKqjyncVGoXFsz2AcuFKe1pwETSsN6 OZncjy32e4ktgs07cWBfx0v62b8md36jau+B6RVnnodaA8++oXl3FRwiEW8XfXWIjy4umIv93tb8 8ekYsfOfWkTSewZYXGoqe4RtK80ulMHb/dh2FZQIFyRdN4HOmB4FYO5sEYFr9YjHLmDkrUgNodJC XCeMe4BO4iaxUQARAQABzRdtYXJrdXMucHJvYnN0QHBvc3Rlby5kZcLBkQQTAQgAOxYhBIJ0GMT0 rFjncjDEczR2H/jnrUPSBQJog714AhsDBQsJCAcCAiICBhUKCQgLAgQWAgMBAh4HAheAAAoJEDR2 H/jnrUPSgdkQAISaTk2D345ehXEkn5z2yUEjaVjHIE7ziqRaOgn/QanCgeTUinIv6L6QXUFvvIfH 1OLPwQ1hfvEg9NnNLyFezWSy6jvoVBTIPqicD/r3FkithnQ1IDkdSjrarPMxJkvuh3l7XZHo49GV HQ8i5zh5w4YISrcEtE99lJisvni2Jqx7we5tey9voQFDyM8jxlSWv3pmoUTCtBkX/eKHJXosgsuS B4TGDCVPOjla/emI5c9MhMG7O4WEEmoSdPbmraPw66YZD6uLyhV4DPHbiDWRzXWnClHSyjB9rky9 lausFxogvu4l9H+KDsXIadNDWdLdu1/enS/wDd9zh5S78rY2jeXaG4mnf4seEKamZ7KQ6FIHrcyP ezdDzssPQcTQcGRMQzCn6wP3tlGk7rsfmyHMlFqdRoNNv+ZER/OkmZFPW655zRfbMi0vtrqK2Awm 9ggobb1oktfd9PPNXMUY+DNVlgR2G7jLnenSoQausLUm0pHoNE8TWFv851Y6SOYnvn488sP1Tki5 F3rKwclawQFHUXTCQw+QSh9ay8xgnNZfH+u9NY7w3gPoeKBOAFcBc2BtzcgekeWS8qgEmm2/oNFV G0ivPQbRx8FjRKbuF7g3YhgNZZ0ac8FneuUtJ2PkSIFTZhaAiC0utvxk0ndmWFiW4acEkMZGrLaM L2zWNjrqwsD2zsFNBGiDvXgBEADCXQy1n7wjRxG12DOVADawjghKcG+5LtEf31WftHKLFbp/HArj BhkT6mj+CCI1ClqY+FYU5CK/s0ScMfLxRGLZ0Ktzawb78vOgBVFT3yB1yWBTewsAXdqNqRooaUNo 8cG/NNJLjhccH/7PO/FWX5qftOVUJ/AIsAhKQJ18Tc8Ik73v427EDxuKb9mTAnYQFA3Ev3hAiVbO 6Rv39amVOfJ8sqwiSUGidj2Fctg2aB5JbeMln0KCUbTD1LhEFepeKypfofAXQbGwaCjAhmkWy/q3 IT1mUrPxOngbxdRoOx1tGUC0HCMUW1sFaJgQPMmDcR0JGPOpgsKnitsSnN7ShcCr1buel7vLnUMD +TAZ5opdoF6HjAvAnBQaijtK6minkrM0seNXnCg0KkV8xhMNa6zCs1rq4GgjNLJue2EmuyHooHA4 7JMoLVHcxVeuNTp6K2+XRx0Pk4e2Lj8IVy9yEYyrywEOC5XRW37KJjsiOAsumi1rkvM7QREWgUDe Xs0+RpxI3QrrANh71fLMRo7LKRF3Gvw13NVCCC9ea20P4PwhgWKStkwO2NO+YJsAoS1QycMi/vKu 0EHhknYXamaSV50oZzHKmX56vEeJHTcngrM8R1SwJCYopCx9gkz90bTVYlitJa5hloWTYeMD7FNj Y6jfVSzgM/K4gMgUNDW/PPGeMwARAQABwsF2BBgBCAAgFiEEgnQYxPSsWOdyMMRzNHYf+OetQ9IF AmiDvXgCGwwACgkQNHYf+OetQ9LHDBAAhk+ab8+WrbS/b1/gYW3q1KDiXU719nCtfkUVXKidW5Ec Idlr5HGt8ilLoxSWT2Zi368iHCXS0WenGgPwlv8ifvB7TOZiiTDZROZkXjEBmU4nYjJ7GymawpWv oQwjMsPuq6ysbzWtOZ7eILx7cI0FjQeJ/Q2baRJub0uAZNwBOxCkAS6lpk5Fntd2u8CWmDQo4SYp xeuQ+pwkp0yEP30RhN2BO2DXiBEGSZSYh+ioGbCHQPIV3iVj0h6lcCPOqopZqyeCfigeacBI0nvN jHWz/spzF3+4OS+3RJvoHtAQmProxyGib8iVsTxgZO3UUi4TSODeEt0i0kHSPY4sCciOyXfAyYoD DFqhRjOEwBBxhr+scU4C1T2AflozvDwq3VSONjrKJUkhd8+WsdXxMdPFgBQuiKKwUy11mz6KQfcR wmDehF3UaUoxa+YIhWPbKmycxuX/D8SvnqavzAeAL1OcRbEI/HsoroVlEFbBRNBZLJUlnTPs8ZcU 4+8rq5YX1GUrJL3jf6SAfSgO7UdkEET3PdcKFYtS+ruV1Cp5V0q4kCfI5jk25iiz8grM2wOzVSsc l1mEkhiEPH87HP0whhb544iioSnumd3HJKL7dzhRegsMizatupp8D65A2JziW0WKopa1iw9fti3A aBeNN4ijKZchBXHPgVx+YtWRHfcm4l8= OpenPGP: url=https://posteo.de/keys/markus.probst@posteo.de.asc; preference=encrypt Implement a wrapper of Vec that guarantees that its content will never be moved, unless the item implements Unpin, allowing PinInit to be initialized on the Vec. Signed-off-by: Markus Probst --- rust/kernel/alloc/kvec.rs | 86 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 86 insertions(+) diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index 3c72e0bdddb8..3576929b2e12 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -21,6 +21,7 @@ slice, slice::SliceIndex, }; +use pin_init::PinInit; mod errors; pub use self::errors::{InsertError, PushError, RemoveError}; @@ -109,6 +110,11 @@ pub struct Vec { _p: PhantomData, } +/// A pinned wrapper of the [`Vec`] type. +/// +/// It is guaranteed that the contents will never be moved, unless T implements Unpin. +pub struct PinnedVec(Vec); + /// Type alias for [`Vec`] with a [`Kmalloc`] allocator. /// /// # Examples @@ -121,6 +127,8 @@ pub struct Vec { /// # Ok::<(), Error>(()) /// ``` pub type KVec = Vec; +/// Type alias for [`PinnedVec`] with a [`Kmalloc`] allocator. +pub type KPinnedVec = PinnedVec; /// Type alias for [`Vec`] with a [`Vmalloc`] allocator. /// @@ -134,6 +142,8 @@ pub struct Vec { /// # Ok::<(), Error>(()) /// ``` pub type VVec = Vec; +/// Type alias for [`PinnedVec`] with a [`Vmalloc`] allocator. +pub type VPinnedVec = PinnedVec; /// Type alias for [`Vec`] with a [`KVmalloc`] allocator. /// @@ -147,6 +157,8 @@ pub struct Vec { /// # Ok::<(), Error>(()) /// ``` pub type KVVec = Vec; +/// Type alias for [`PinnedVec`] with a [`KVmalloc`] allocator. +pub type KVPinnedVec = PinnedVec; // SAFETY: `Vec` is `Send` if `T` is `Send` because `Vec` owns its elements. unsafe impl Send for Vec @@ -1294,6 +1306,80 @@ fn drop(&mut self) { } } +impl PinnedVec { + /// Creates a new [`PinnedVec`] instance with at least the given capacity. + pub fn with_capacity(capacity: usize, flags: Flags) -> Result { + Vec::with_capacity(capacity, flags).map(Self) + } + + /// Shortens the vector, setting the length to `len` and drops the removed values. + /// If `len` is greater than or equal to the current length, this does nothing. + /// + /// This has no effect on the capacity and will not allocate. + pub fn truncate(&mut self, len: usize) { + self.0.truncate(len); + } + + /// Pin-initializes P and appends it to the back of the [`Vec`] instance without reallocating. + pub fn push_pin_init>(&mut self, init: P) -> Result<(), E> + where + E: From>, + { + if self.0.len() < self.0.capacity() { + let spare = self.0.spare_capacity_mut(); + // SAFETY: the length is less than the capacity, so `spare` is non-empty. + unsafe { init.__pinned_init(spare.get_unchecked_mut(0).as_mut_ptr())? }; + // SAFETY: We just initialised the first spare entry, so it is safe to + // increase the length by 1. We also know that the new length is <= capacity. + unsafe { self.0.inc_len(1) }; + Ok(()) + } else { + Err(E::from(PushError(init))) + } + } + + /// Removes the last element from a vector and drops it returning true, or false if it is empty. + pub fn pop(&mut self) -> bool { + if self.is_empty() { + return false; + } + + // SAFETY: We just checked that the length is at least one. + let ptr: *mut [T] = unsafe { self.0.dec_len(1) }; + + // SAFETY: the contract of `dec_len` guarantees that the elements in `ptr` are + // valid elements whose ownership has been transferred to the caller. + unsafe { ptr::drop_in_place(ptr) }; + true + } +} + +impl Deref for PinnedVec { + type Target = Vec; + + fn deref(&self) -> &Self::Target { + &self.0 + } +} + +impl DerefMut for PinnedVec { + fn deref_mut(&mut self) -> &mut Self::Target { + &mut self.0 + } +} + +impl From> for PinnedVec { + fn from(value: Vec) -> Self { + Self(value) + } +} + +impl From> for Vec { + fn from(value: PinnedVec) -> Self { + value.0 + } +} + #[macros::kunit_tests(rust_kvec_kunit)] mod tests { use super::*; -- 2.49.1