From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 0DC397082D; Thu, 18 Jun 2026 23:08:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781824132; cv=none; b=eASKTF9KqiFw80m/FZQPr4yrDKjLsCbr2jHr/+jUuV1IjaAAs1aVmdvGVSRjkBxNl0ZnhIbUXDj2fGzQHjqo2TC7Mhvuldo2/31BcvamGNr79f5HvdT1ELXRO3Sgd53TVCwtGq0Pf6fWlvybptmNKWc0Vm8YUPNpCdjUJyeXxuQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781824132; c=relaxed/simple; bh=nHU7F6R/ddTEuHFMZbqtUNAEkj7f+Wsp9Rinn6XBGDU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=B0OkG52Cmbpl4/5faIQuCwl8tHdzPaFNvsi3dPWpMD6e8VSvv5yjoXFnj75iKhhPda7orq6DZlAPsaTBbFgQENjDRIGT7uHjP62f4xbqIzTUIB6dXl6tU++FasWHwf+oZm37ZCZ1l5Kwd2e3cf55hHexPEMrUNtjEnxy3dJ/5iI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GgDkpvVe; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GgDkpvVe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BA6201F000E9; Thu, 18 Jun 2026 23:08:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781824130; bh=IFzNgkG2m6LHm/n3B0bxBt/0Kp+5tRid/Y2vmPN6Huk=; h=From:To:Cc:Subject:Date; b=GgDkpvVe1RBzO2seIT4BcWsJJ3VDTGBlmFmkv0wvl6gwpAn2VaUfbrlZtmcP93hUr +D65Ip+5tDKdLWvhcgGjLur4Qik4YKohvkWYwE4WfKUbkCMRou+Vgo0WvJUPKPRF4m +/xjr1h/D95QngnGCr4mMHGik1F8r5zgQHM52KO7ci5EImMc3owtOEM4HeIJ1eoXKg IRDQApzfVIcV8mq3rN807YRvXcdY77oLVDkX2LlUBtPz4AgakAH1xQkhwhKY4CQv/6 f8qH0vlqlt01zFCFAACJRuo/gG21gAimMGOZSC346L/c/s8FCm8QcaiuhqsWMleXq9 ZeXUZYjMBYubw== From: Danilo Krummrich To: gregkh@linuxfoundation.org, rafael@kernel.org, dakr@kernel.org, ojeda@kernel.org, boqun@kernel.org, gary@garyguo.net, bjorn3_gh@protonmail.com, lossin@kernel.org, a.hindborg@kernel.org, aliceryhl@google.com, tmgross@umich.edu, acourbot@nvidia.com, ecourtney@nvidia.com, m.wilczynski@samsung.com, david.m.ertman@intel.com, ira.weiny@intel.com, leon@kernel.org, daniel.almeida@collabora.com, bhelgaas@google.com, kwilczynski@kernel.org Cc: driver-core@lists.linux.dev, linux-kernel@vger.kernel.org, nova-gpu@lists.linux.dev, dri-devel@lists.freedesktop.org, linux-pwm@vger.kernel.org, rust-for-linux@vger.kernel.org Subject: [PATCH v3 0/7] ForLt/CovariantForLt split, auxiliary closure API and DevresLt Date: Fri, 19 Jun 2026 01:08:26 +0200 Message-ID: <20260618230834.812007-1-dakr@kernel.org> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: nova-gpu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The ForLt trait currently guarantees covariance, which allows safe lifetime shortening via cast_ref(). However, some types (e.g. those containing Mutex<&'bound T>) are invariant over their lifetime parameter and cannot safely use cast_ref(). This series splits ForLt into two traits: - ForLt: base trait for all lifetime-parameterized types, providing only the Of<'a> GAT. - CovariantForLt: unsafe subtrait that guarantees covariance, providing a safe cast_ref() method. For invariant types, a closure-based API (registration_data_with()) is added to the auxiliary subsystem. The closure's HRTB prevents the caller from choosing a concrete lifetime, which would be unsound for invariant types. On top of that, this series adds DevresLt, a thin wrapper around Devres> that shortens the stored 'static lifetime back to the caller's borrow scope. DevresLt provides both closure-based access (access_with/try_access_with for ForLt types) and direct reference access (access/try_access for CovariantForLt types). Also implement ForLt and CovariantForLt for Bar, IoMem and ExclusiveIoMem, and update their into_devres() methods to return DevresLt. Provide convenience type aliases DevresBar, DevresIoMem and DevresExclusiveIoMem. Changes in v3: - Keep UnsafeForLtImpl as the shared helper for both ForLt! and CovariantForLt!, distinguished by const generic N - Remove cast_ref_unchecked() from ForLt; lifetime shortening is handled by borrowing with the target lifetime directly or by decoupling the HRTB from the outer reference lifetime Changes in v2: - Fold the ForLt -> CovariantForLt rename and the new ForLt base trait into this series - Add closure-based registration_data_with() for auxiliary ForLt types - Add auxiliary sample demonstrating ForLt with an invariant Mutex type - DevresLt: add closure-based access_with()/try_access_with() for ForLt types alongside direct access()/try_access() for CovariantForLt types - Make DevresLt::new() unsafe; callers must guarantee the data outlives the device binding - Implement both ForLt and CovariantForLt (previously just ForLt) for Bar, IoMem, ExclusiveIoMem - Various safety comment and documentation improvements Danilo Krummrich (7): rust: types: rename ForLt to CovariantForLt rust: types: introduce ForLt base trait for CovariantForLt rust: auxiliary: add registration_data_with() for ForLt types rust: auxiliary: sample: demonstrate ForLt with invariant Mutex type rust: devres: add DevresLt for ForLt-aware device resource access rust: pci: return DevresLt from Bar::into_devres() rust: io: mem: return DevresLt from IoMem/ExclusiveIoMem::into_devres() drivers/gpu/nova-core/driver.rs | 4 +- drivers/pwm/pwm_th1520.rs | 5 +- rust/kernel/auxiliary.rs | 76 +++++++++++++++----- rust/kernel/devres.rs | 100 ++++++++++++++++++++++++++ rust/kernel/io/mem.rs | 65 +++++++++++------ rust/kernel/pci.rs | 1 + rust/kernel/pci/io.rs | 37 +++++++--- rust/kernel/types.rs | 1 + rust/kernel/types/for_lt.rs | 95 +++++++++++++++++------- rust/macros/for_lt.rs | 53 +++++++++++--- rust/macros/lib.rs | 18 ++++- samples/rust/rust_driver_auxiliary.rs | 96 ++++++++++++++++++------- 12 files changed, 432 insertions(+), 119 deletions(-) base-commit: 83f1454877cc292b88baf13c829c16ce6937d120 -- 2.54.0