From nobody Thu Sep 19 16:02:02 2024 Received: from mail-yb1-f202.google.com (mail-yb1-f202.google.com [209.85.219.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 20AE41CDA2A for ; Thu, 22 Aug 2024 16:38:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724344687; cv=none; b=mW+zZfk0KNt2GywL6MUipI3RyP88UuxYFl2L9WBbWILLOzt0VLwsAWwhwFvWZalGiM3aoWkzTq3hdJJ0atv7kOmve6zz8wOjC4IUaKyEP0CA15EL/J/JiPC1AvbCbTE7JesrY3C/urbRf2xPwPw+oZKjbV6B8C05bh0qNsBeVf4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724344687; c=relaxed/simple; bh=CHEPUnEo1ublThVvZv27KVkUnXnCL42Vbhba4e3iR0E=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=TKioQb6bWf3JMH+9TUvse8TJI4oLPOCm6c4Uf2X5cdxM+lVSxk/LgVEHNdWTk8XObggYgG0km3jXg8CasP736VODshlDJMbwvWNeuqJQ33eBT/hvth/vxbPDWclItvOCcsNCfav2GaMmLtN28oJTQrEhhJpF+VQhka4QAQeEqok= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--mattgilbride.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=4Xby0inC; arc=none smtp.client-ip=209.85.219.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--mattgilbride.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="4Xby0inC" Received: by mail-yb1-f202.google.com with SMTP id 3f1490d57ef6-e1653c8a32eso1644835276.3 for ; Thu, 22 Aug 2024 09:38:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1724344683; x=1724949483; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=/j9j1rbxZpBdi5oEplcJiifVcCwTYu4oYwyR+PLoz+E=; b=4Xby0inC9CROxN8/H2N6j8oSyRhf76C8RTrWUKoz+5a/uMMSBK/33CQqRv3zxvf52W 5nIIGXJhQ9UPwc/m7TMfsPr1ZfzLf9ep7DM+2CVYTKr5S17ZjryL5oS1AYsoMjpfxfcx yefaPoTTxnWSah/azDG6xAGEFMIx4fVwJgNAOghCmITVlwwf5DB1Ux4l0w5nuNAcQ5UD vY+tsWlrflRNrNn8QqJagBaic/CmG2XMgzFJGml1QaTPRYr+aRCJRocFZNsOrNUmXriu njVqNv3ppn31Vi/PFOm1XSGE/gc1KF0j26Txv2XAtgWl/6lbHIYMUJdQYj9znvgD7kE9 SaGw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724344683; x=1724949483; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=/j9j1rbxZpBdi5oEplcJiifVcCwTYu4oYwyR+PLoz+E=; b=mjj5A8acEbuC23bexWPK2GEzoXahzwx8pcTXjlwAlG+VSzJhmuvNRbHoS4czPBUWEd /L8JuRzd9dKGpNVXZrKygsYn2i+rZHMUjFsGqxnH7HwKiskDiOlMgXxLoxrHP9i4CBiF is82t3EXaMwVv0vP7yVbjr9K98Q7a9REgTDGVhYRT8BAT4204tuG7WxlvLt/Ee710Gp4 g4b5S5N9/1LhgknzyXYgM0WmDLKSLpAC2IuyD4DYzVktwHp8G8JQQqT4cKV8afIR2lQg Z81VRvxfvhGvabPlm1RI6RPQrAa7bN1cpPkuZIffHBFAL9CPsPj1mG8cDGR+W7775nZb 8NnQ== X-Forwarded-Encrypted: i=1; AJvYcCVhSO/xPqN6YnRGeJMr9bkw9ZD1yLTEfuZhfvoilrEGXh7tcbKwsBghg9hS5jSE0rjMSP9xag9Uze5X4Is=@vger.kernel.org X-Gm-Message-State: AOJu0YzyOfreC6RnxRvtTrQ+mR/AonXCvbK9gvdfgVG3lCb4H7Jo6+WI +pbGJk8aH+7DxvI3Pxt6BqpDHGQMWVD+dYHshOD/Kd9YSd/Ke+X0+lVReJHROKpgB73I5icajvI BnWJ70ltg1zOdbHxZoFVhjSSKyw== X-Google-Smtp-Source: AGHT+IGVt5PpJ0FznyUHRjkqyMLSJdpcH7tywDb/fsIlyRnaTGNjWbLMhIZRmp4Q/xBghf0C3a2e2PgsKQnDV6I6gXo= X-Received: from mattgilbride.c.googlers.com ([fda3:e722:ac3:cc00:2b:7d90:c0a8:2ac5]) (user=mattgilbride job=sendgmr) by 2002:a5b:60a:0:b0:e0b:ab63:b9c8 with SMTP id 3f1490d57ef6-e17a4521d12mr76276.11.1724344683085; Thu, 22 Aug 2024 09:38:03 -0700 (PDT) Date: Thu, 22 Aug 2024 16:37:55 +0000 In-Reply-To: <20240822-b4-rbtree-v12-0-014561758a57@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240822-b4-rbtree-v12-0-014561758a57@google.com> X-Mailer: b4 0.13.0 Message-ID: <20240822-b4-rbtree-v12-3-014561758a57@google.com> Subject: [PATCH v12 3/5] rust: rbtree: add mutable iterator From: Matt Gilbride To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , "=?utf-8?q?Bj=C3=B6rn_Roy_Baron?=" , Benno Lossin , Andreas Hindborg , Alice Ryhl , Greg Kroah-Hartman , "=?utf-8?q?Arve_Hj=C3=B8nnev=C3=A5g?=" , Todd Kjos , Martijn Coenen , Joel Fernandes , Carlos Llamas , Suren Baghdasaryan , Christian Brauner Cc: Rob Landley , Davidlohr Bueso , Michel Lespinasse , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Matt Gilbride Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Wedson Almeida Filho Add mutable Iterator implementation for `RBTree`, allowing iteration over (key, value) pairs in key order. Only values are mutable, as mutating keys implies modifying a node's position in the tree. Mutable iteration is used by the binder driver during shutdown to clean up the tree maintained by the "range allocator" [1]. Link: https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-6-08ba= 9197f637@google.com/ [1] Signed-off-by: Wedson Almeida Filho Reviewed-by: Alice Ryhl Tested-by: Alice Ryhl Reviewed-by: Boqun Feng Reviewed-by: Benno Lossin Signed-off-by: Matt Gilbride --- rust/kernel/rbtree.rs | 103 +++++++++++++++++++++++++++++++++++++++++++---= ---- 1 file changed, 89 insertions(+), 14 deletions(-) diff --git a/rust/kernel/rbtree.rs b/rust/kernel/rbtree.rs index 29e7a0795266..399ace4e1949 100644 --- a/rust/kernel/rbtree.rs +++ b/rust/kernel/rbtree.rs @@ -12,7 +12,7 @@ cmp::{Ord, Ordering}, marker::PhantomData, mem::MaybeUninit, - ptr::{addr_of_mut, NonNull}, + ptr::{addr_of_mut, from_mut, NonNull}, }; =20 /// A red-black tree with owned nodes. @@ -194,11 +194,31 @@ pub fn new() -> Self { =20 /// Returns an iterator over the tree nodes, sorted by key. pub fn iter(&self) -> Iter<'_, K, V> { - // INVARIANT: `bindings::rb_first` returns a valid pointer to a tr= ee node given a valid pointer to a tree root. Iter { _tree: PhantomData, - // SAFETY: `self.root` is a valid pointer to the tree root. - next: unsafe { bindings::rb_first(&self.root) }, + // INVARIANT: + // - `self.root` is a valid pointer to a tree root. + // - `bindings::rb_first` produces a valid pointer to a node= given `root` is valid. + iter_raw: IterRaw { + // SAFETY: by the invariants, all pointers are valid. + next: unsafe { bindings::rb_first(&self.root) }, + _phantom: PhantomData, + }, + } + } + + /// Returns a mutable iterator over the tree nodes, sorted by key. + pub fn iter_mut(&mut self) -> IterMut<'_, K, V> { + IterMut { + _tree: PhantomData, + // INVARIANT: + // - `self.root` is a valid pointer to a tree root. + // - `bindings::rb_first` produces a valid pointer to a node= given `root` is valid. + iter_raw: IterRaw { + // SAFETY: by the invariants, all pointers are valid. + next: unsafe { bindings::rb_first(from_mut(&mut self.root)= ) }, + _phantom: PhantomData, + }, } } =20 @@ -211,6 +231,11 @@ pub fn keys(&self) -> impl Iterator { pub fn values(&self) -> impl Iterator { self.iter().map(|(_, v)| v) } + + /// Returns a mutable iterator over the values of the nodes in the tre= e, sorted by key. + pub fn values_mut(&mut self) -> impl Iterator { + self.iter_mut().map(|(_, v)| v) + } } =20 impl RBTree @@ -414,13 +439,9 @@ fn into_iter(self) -> Self::IntoIter { /// An iterator over the nodes of a [`RBTree`]. /// /// Instances are created by calling [`RBTree::iter`]. -/// -/// # Invariants -/// - `self.next` is a valid pointer. -/// - `self.next` points to a node stored inside of a valid `RBTree`. pub struct Iter<'a, K, V> { _tree: PhantomData<&'a RBTree>, - next: *mut bindings::rb_node, + iter_raw: IterRaw, } =20 // SAFETY: The [`Iter`] gives out immutable references to K and V, so it h= as the same @@ -434,21 +455,75 @@ unsafe impl<'a, K: Sync, V: Sync> Sync for Iter<'a, K= , V> {} impl<'a, K, V> Iterator for Iter<'a, K, V> { type Item =3D (&'a K, &'a V); =20 + fn next(&mut self) -> Option { + // SAFETY: Due to `self._tree`, `k` and `v` are valid for the life= time of `'a`. + self.iter_raw.next().map(|(k, v)| unsafe { (&*k, &*v) }) + } +} + +impl<'a, K, V> IntoIterator for &'a mut RBTree { + type Item =3D (&'a K, &'a mut V); + type IntoIter =3D IterMut<'a, K, V>; + + fn into_iter(self) -> Self::IntoIter { + self.iter_mut() + } +} + +/// A mutable iterator over the nodes of a [`RBTree`]. +/// +/// Instances are created by calling [`RBTree::iter_mut`]. +pub struct IterMut<'a, K, V> { + _tree: PhantomData<&'a mut RBTree>, + iter_raw: IterRaw, +} + +// SAFETY: The [`IterMut`] has exclusive access to both `K` and `V`, so it= is sufficient to require them to be `Send`. +// The iterator only gives out immutable references to the keys, but since= the iterator has excusive access to those same +// keys, `Send` is sufficient. `Sync` would be okay, but it is more restri= ctive to the user. +unsafe impl<'a, K: Send, V: Send> Send for IterMut<'a, K, V> {} + +// SAFETY: The [`IterMut`] gives out immutable references to K and mutable= references to V, so it has the same +// thread safety requirements as mutable references. +unsafe impl<'a, K: Sync, V: Sync> Sync for IterMut<'a, K, V> {} + +impl<'a, K, V> Iterator for IterMut<'a, K, V> { + type Item =3D (&'a K, &'a mut V); + + fn next(&mut self) -> Option { + self.iter_raw.next().map(|(k, v)| + // SAFETY: Due to `&mut self`, we have exclusive access to `k`= and `v`, for the lifetime of `'a`. + unsafe { (&*k, &mut *v) }) + } +} + +/// A raw iterator over the nodes of a [`RBTree`]. +/// +/// # Invariants +/// - `self.next` is a valid pointer. +/// - `self.next` points to a node stored inside of a valid `RBTree`. +struct IterRaw { + next: *mut bindings::rb_node, + _phantom: PhantomData (K, V)>, +} + +impl Iterator for IterRaw { + type Item =3D (*mut K, *mut V); + fn next(&mut self) -> Option { if self.next.is_null() { return None; } =20 - // SAFETY: By the type invariant of `Iter`, `self.next` is a valid= node in an `RBTree`, + // SAFETY: By the type invariant of `IterRaw`, `self.next` is a va= lid node in an `RBTree`, // and by the type invariant of `RBTree`, all nodes point to the l= inks field of `Node` objects. - let cur =3D unsafe { container_of!(self.next, Node, links) }; + let cur =3D unsafe { container_of!(self.next, Node, links) }= .cast_mut(); =20 // SAFETY: `self.next` is a valid tree node by the type invariants. self.next =3D unsafe { bindings::rb_next(self.next) }; =20 - // SAFETY: By the same reasoning above, it is safe to dereference = the node. Additionally, - // it is ok to return a reference to members because the iterator = must outlive it. - Some(unsafe { (&(*cur).key, &(*cur).value) }) + // SAFETY: By the same reasoning above, it is safe to dereference = the node. + Some(unsafe { (addr_of_mut!((*cur).key), addr_of_mut!((*cur).value= )) }) } } =20 --=20 2.46.0.184.g6999bdac58-goog