From patchwork Tue Mar 25 20:07:41 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tamir Duberstein X-Patchwork-Id: 14029475 Received: from mail-qv1-f49.google.com (mail-qv1-f49.google.com [209.85.219.49]) (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 7F2F6265CB9; Tue, 25 Mar 2025 20:07:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.49 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742933273; cv=none; b=HCuEA5rCb0O7q7SSbmGaxMZpDLLBe0kUYPeQwdvJBkg6DoKtBojg0rdBa2HY5nthQvlG3EhjCGbmDIkkrkaCkoO8y9psOXT2FzasHAYgRnAbv9rgU+tmhlLJRXakZl1li9DAIBe1OfL8pD/SdhzT8uKVHBCYL03wApIFYAMNWzM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742933273; c=relaxed/simple; bh=uPLPWLWTd7l7BqiDQb2Zl5Fp/2o2CJiW7477tqQuo5g=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=obqFxNBK1LdPdGiRC8rwSMBcWs9z5jkPXOCXPuy0fP92QjatkK8FZAhNWBtXjsIJFJuQGIuDx1kSnN4Z9EK62InUlju/2S7EW2wQw5WznrFM9bvyozDt3zawJK9/lUpQoYrqXh07QQtIoh/w9bsZlbb5kCQ7sNu69+5cuNXPI0Q= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=llh+shr9; arc=none smtp.client-ip=209.85.219.49 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="llh+shr9" Received: by mail-qv1-f49.google.com with SMTP id 6a1803df08f44-6e8ec399427so47545136d6.2; Tue, 25 Mar 2025 13:07:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1742933270; x=1743538070; darn=vger.kernel.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=vUyKcLlRsxCPf3w4Hv0sykJZjBz7c3E/OZe1MEqXL5I=; b=llh+shr9QkgUpmho4YsxLcjX/Tu914pYUxe+r+y0gOpMEQBISkEYbvV6Am/fkacivG qTCfEOHweHgEmca9Jtq402iQ4DZWAFLlnlNbjaW3Bq+XsKw/5yQbg5fI9TBd6qGA5O5H Rx92xtFG28FusJo1NDeWseCwEBFBrsefzkxrwlN6Pp4XKK2lifpk+QLcHj5ze4C3YZMs Ps4yn18F442GoZOo9EFJvGx2wafrOUC3PsTTQDkiNtoUrv4vf2XbwftdMXF9Bx88wG3D kSRHf2k13FTMsvYTviD2xC3SisKdNQFmwXQ95LaOe3MB6AUOpu3TJd8HHo4F9lH46CGe LhWQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1742933270; x=1743538070; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=vUyKcLlRsxCPf3w4Hv0sykJZjBz7c3E/OZe1MEqXL5I=; b=E8L/Acie6Vrfwf6So4yU21OEe8LdBOMO6qJVHF/Ed6CdGH3meNM0icOvdjomXaaSTx N4ErJdKJRajkIJaIfJVXAApXd55vWCEvgorXtqF3EmMw0A/y9YbsuUtpcQkP8fdSFH6Y Wv4tty1QG7wzb1//S3tGIOR09v+hCkGGoH84edC+PTTQ6kybtK2sqFxjExZ6AZ7leeyf 9LM12YyyjMxBJ1SiZJcHIiWm1Gtwr4jm9uafypkdqtnpzwvCtPBs/01XYKvTx8PE4IB2 +OEDSrM1vDoWVp+uMLUEBfAETDtMNDhQzumCbH+c/kTNIfJ3AQTsWh7OMid/nmPh57+A V/YA== X-Forwarded-Encrypted: i=1; AJvYcCUBsghjhcao84M8e09LwBLSw+wsK8gQT/8fJxt/UwQtmFhSMf0rRGAYKHo6NIQsu53Mv9oN+WebbfY+@vger.kernel.org, AJvYcCVC4/ZJZ3N/a+nWATizccNYNLgGGsnCORTKCQRAwTFJp68YLSDRtvCmP+W4wNQwjTuNkpWd1UB7@vger.kernel.org, AJvYcCVXAT5Fh0UsVYZdQ6SOjgk6BYyi8rcBkxz0KwLXpM6UeP3+gnnxZvUgzduzEh9MqIydEO07vJLYmK6j3RGu4Gc=@vger.kernel.org, AJvYcCVuji+lAONPF3oBuEVHjEby9c1xfm6Ml4CaIkIbG9Y8iuS5sVH1n35PC1omlbHWzKQiOpg2+vPwhDzB61K/Brdr@vger.kernel.org, AJvYcCWCzb7ZJijTbNc0uXeoswmrYlgfy0n5E0uemrI/ablov/xhCllNeFgZRLNVhHIKch7M85//aiy4X8lJtoTJ@vger.kernel.org, AJvYcCWnIjF0tYgwH4WF65yOERi895Q26iK6AizFK29/xOOJEMGCjuOtY5g8Falf5hJxJ1wsX77LdNuLbCco@vger.kernel.org, AJvYcCXaO1rw9pxJ58mlW1pJU4yX5XITG5KND4Av2REXcDz+u2rqqIGDvcvVD5jVIUgnqMuT8Yd+xT5rBVGHlV0=@vger.kernel.org X-Gm-Message-State: AOJu0YwjFti8u1X3ygiNQMM/6QsF/M+J7KkCtqqec/IrNxvFqBgCNIQm 34NjoTfEU1tFy252dq8hNoz0FY/dJlCNXTQHfMe1ZH2fFWTuBl4N X-Gm-Gg: ASbGncs32mvEPi84FcucsUm0hz2sSK5bqXe7YyKtXbZZp5owkHh29DeHhrOmgMM/B0M UmIU7VCVMD9S7cIFOkydx5KMz3/PGG6UBA7fGf6C5SQCSTjeURCLtmFP0stlqhDDwLu+/PmRJr+ uPyjdlOWjk15a2c6WyF/XYPDagzf0oY0WoHhtvULon8IQQ4h/+eby01dX3cTqbrgnQHKN65mMhy harjTISA9DCDIxvx0edvDYM+ajE/Xwr7PcztrpKNP1qbuVArubNw9TKej0mUlD96BCfpfYigupe q5PZ0kBv7ELqgLZ1/0iWi5HWG9MYez0BCsgTrgNmawqSgbSllFrc5phfzMTRi4XnbHXW35+HFbv F38amQ9ew5wEHcv/+vu+2AuQV+WpZ2f9sys1ghAVcOcA5/uUzatXPPQ== X-Google-Smtp-Source: AGHT+IF0FEVjkmBVxSw4zx3ID9z15/27aOJZzeAhYx7Krhmei89O1rW0ABUkTs86J2nx907JKAmhLQ== X-Received: by 2002:a05:6214:4007:b0:6e8:9866:7398 with SMTP id 6a1803df08f44-6eb3f2e5534mr243298056d6.22.1742933269992; Tue, 25 Mar 2025 13:07:49 -0700 (PDT) Received: from 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa ([2620:10d:c091:600::1:38f6]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6eb3ef31810sm59790316d6.64.2025.03.25.13.07.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 25 Mar 2025 13:07:49 -0700 (PDT) From: Tamir Duberstein Date: Tue, 25 Mar 2025 16:07:41 -0400 Subject: [PATCH v7 1/7] rust: retain pointer mut-ness in `container_of!` Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250325-ptr-as-ptr-v7-1-87ab452147b9@gmail.com> References: <20250325-ptr-as-ptr-v7-0-87ab452147b9@gmail.com> In-Reply-To: <20250325-ptr-as-ptr-v7-0-87ab452147b9@gmail.com> To: Masahiro Yamada , Nathan Chancellor , Nicolas Schier , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Greg Kroah-Hartman , "Rafael J. Wysocki" , Brendan Higgins , David Gow , Rae Moar , Bjorn Helgaas , Luis Chamberlain , Russ Weight , Rob Herring , Saravana Kannan , Abdiel Janulgue , Daniel Almeida , Robin Murphy , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , FUJITA Tomonori Cc: linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com, linux-pci@vger.kernel.org, linux-block@vger.kernel.org, devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org, netdev@vger.kernel.org, Tamir Duberstein X-Mailer: b4 0.15-dev Avoid casting the input pointer to `*const _`, allowing the output pointer to be `*mut` if the input is `*mut`. This allows a number of `*const` to `*mut` conversions to be removed at the cost of slightly worse ergonomics when the macro is used with a reference rather than a pointer; the only example of this was in the macro's own doctest. Reviewed-by: Benno Lossin Reviewed-by: Alice Ryhl Signed-off-by: Tamir Duberstein --- rust/kernel/lib.rs | 5 ++--- rust/kernel/pci.rs | 2 +- rust/kernel/platform.rs | 2 +- rust/kernel/rbtree.rs | 23 ++++++++++------------- 4 files changed, 14 insertions(+), 18 deletions(-) diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index ba0f3b0297b2..cffa0d837f06 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -190,7 +190,7 @@ fn panic(info: &core::panic::PanicInfo<'_>) -> ! { /// } /// /// let test = Test { a: 10, b: 20 }; -/// let b_ptr = &test.b; +/// let b_ptr: *const _ = &test.b; /// // SAFETY: The pointer points at the `b` field of a `Test`, so the resulting pointer will be /// // in-bounds of the same allocation as `b_ptr`. /// let test_alias = unsafe { container_of!(b_ptr, Test, b) }; @@ -199,9 +199,8 @@ fn panic(info: &core::panic::PanicInfo<'_>) -> ! { #[macro_export] macro_rules! container_of { ($ptr:expr, $type:ty, $($f:tt)*) => {{ - let ptr = $ptr as *const _ as *const u8; let offset: usize = ::core::mem::offset_of!($type, $($f)*); - ptr.sub(offset) as *const $type + $ptr.byte_sub(offset).cast::<$type>() }} } diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs index f7b2743828ae..271a7690a9a0 100644 --- a/rust/kernel/pci.rs +++ b/rust/kernel/pci.rs @@ -364,7 +364,7 @@ pub unsafe fn from_dev(dev: ARef) -> Self { fn as_raw(&self) -> *mut bindings::pci_dev { // SAFETY: By the type invariant `self.0.as_raw` is a pointer to the `struct device` // embedded in `struct pci_dev`. - unsafe { container_of!(self.0.as_raw(), bindings::pci_dev, dev) as _ } + unsafe { container_of!(self.0.as_raw(), bindings::pci_dev, dev) } } /// Returns the PCI vendor ID. diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs index 1297f5292ba9..84a4ecc642a1 100644 --- a/rust/kernel/platform.rs +++ b/rust/kernel/platform.rs @@ -189,7 +189,7 @@ unsafe fn from_dev(dev: ARef) -> Self { fn as_raw(&self) -> *mut bindings::platform_device { // SAFETY: By the type invariant `self.0.as_raw` is a pointer to the `struct device` // embedded in `struct platform_device`. - unsafe { container_of!(self.0.as_raw(), bindings::platform_device, dev) }.cast_mut() + unsafe { container_of!(self.0.as_raw(), bindings::platform_device, dev) } } } diff --git a/rust/kernel/rbtree.rs b/rust/kernel/rbtree.rs index 5246b2c8a4ff..8d978c896747 100644 --- a/rust/kernel/rbtree.rs +++ b/rust/kernel/rbtree.rs @@ -424,7 +424,7 @@ pub fn cursor_lower_bound(&mut self, key: &K) -> Option> while !node.is_null() { // SAFETY: By the type invariant of `Self`, all non-null `rb_node` pointers stored in `self` // point to the links field of `Node` objects. - let this = unsafe { container_of!(node, Node, links) }.cast_mut(); + let this = unsafe { container_of!(node, Node, links) }; // SAFETY: `this` is a non-null node so it is valid by the type invariants. let this_key = unsafe { &(*this).key }; // SAFETY: `node` is a non-null node so it is valid by the type invariants. @@ -496,7 +496,7 @@ fn drop(&mut self) { // but it is not observable. The loop invariant is still maintained. // SAFETY: `this` is valid per the loop invariant. - unsafe { drop(KBox::from_raw(this.cast_mut())) }; + unsafe { drop(KBox::from_raw(this)) }; } } } @@ -761,7 +761,7 @@ pub fn remove_current(self) -> (Option, RBTreeNode) { let next = self.get_neighbor_raw(Direction::Next); // SAFETY: By the type invariant of `Self`, all non-null `rb_node` pointers stored in `self` // point to the links field of `Node` objects. - let this = unsafe { container_of!(self.current.as_ptr(), Node, links) }.cast_mut(); + let this = unsafe { container_of!(self.current.as_ptr(), Node, links) }; // SAFETY: `this` is valid by the type invariants as described above. let node = unsafe { KBox::from_raw(this) }; let node = RBTreeNode { node }; @@ -806,7 +806,7 @@ fn remove_neighbor(&mut self, direction: Direction) -> Option> unsafe { bindings::rb_erase(neighbor, addr_of_mut!(self.tree.root)) }; // SAFETY: By the type invariant of `Self`, all non-null `rb_node` pointers stored in `self` // point to the links field of `Node` objects. - let this = unsafe { container_of!(neighbor, Node, links) }.cast_mut(); + let this = unsafe { container_of!(neighbor, Node, links) }; // SAFETY: `this` is valid by the type invariants as described above. let node = unsafe { KBox::from_raw(this) }; return Some(RBTreeNode { node }); @@ -912,7 +912,7 @@ unsafe fn to_key_value_mut<'b>(node: NonNull) -> (&'b K, &'b unsafe fn to_key_value_raw<'b>(node: NonNull) -> (&'b K, *mut V) { // SAFETY: By the type invariant of `Self`, all non-null `rb_node` pointers stored in `self` // point to the links field of `Node` objects. - let this = unsafe { container_of!(node.as_ptr(), Node, links) }.cast_mut(); + let this = unsafe { container_of!(node.as_ptr(), Node, links) }; // SAFETY: The passed `node` is the current node or a non-null neighbor, // thus `this` is valid by the type invariants. let k = unsafe { &(*this).key }; @@ -1021,7 +1021,7 @@ fn next(&mut self) -> Option { // SAFETY: By the type invariant of `IterRaw`, `self.next` is a valid node in an `RBTree`, // and by the type invariant of `RBTree`, all nodes point to the links field of `Node` objects. - let cur = unsafe { container_of!(self.next, Node, links) }.cast_mut(); + let cur = unsafe { container_of!(self.next, Node, links) }; // SAFETY: `self.next` is a valid tree node by the type invariants. self.next = unsafe { bindings::rb_next(self.next) }; @@ -1216,7 +1216,7 @@ pub fn get_mut(&mut self) -> &mut V { // SAFETY: // - `self.node_links` is a valid pointer to a node in the tree. // - We have exclusive access to the underlying tree, and can thus give out a mutable reference. - unsafe { &mut (*(container_of!(self.node_links, Node, links).cast_mut())).value } + unsafe { &mut (*(container_of!(self.node_links, Node, links))).value } } /// Converts the entry into a mutable reference to its value. @@ -1226,7 +1226,7 @@ pub fn into_mut(self) -> &'a mut V { // SAFETY: // - `self.node_links` is a valid pointer to a node in the tree. // - This consumes the `&'a mut RBTree`, therefore it can give out a mutable reference that lives for `'a`. - unsafe { &mut (*(container_of!(self.node_links, Node, links).cast_mut())).value } + unsafe { &mut (*(container_of!(self.node_links, Node, links))).value } } /// Remove this entry from the [`RBTree`]. @@ -1239,9 +1239,7 @@ pub fn remove_node(self) -> RBTreeNode { RBTreeNode { // SAFETY: The node was a node in the tree, but we removed it, so we can convert it // back into a box. - node: unsafe { - KBox::from_raw(container_of!(self.node_links, Node, links).cast_mut()) - }, + node: unsafe { KBox::from_raw(container_of!(self.node_links, Node, links)) }, } } @@ -1272,8 +1270,7 @@ fn replace(self, node: RBTreeNode) -> RBTreeNode { // SAFETY: // - `self.node_ptr` produces a valid pointer to a node in the tree. // - Now that we removed this entry from the tree, we can convert the node to a box. - let old_node = - unsafe { KBox::from_raw(container_of!(self.node_links, Node, links).cast_mut()) }; + let old_node = unsafe { KBox::from_raw(container_of!(self.node_links, Node, links)) }; RBTreeNode { node: old_node } }