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 1D7EC5476C3; Tue, 29 Sep 2026 17:58:32 +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=1790704713; cv=none; b=KyMrAwK5u4WDgoKelDq3yHghFGsD//qS2pxgWq3DnxiCHPAtStSdJJkkILZvkrqqsPgqUA63Esg5UFPqtk/vJ3a0a5AoSqTXSOMLKd5/7U+2WGJ0O7XpNJ/kOeFvlAmXc1XDyxajUEDMQ0WEaz/IgcHkHw+Wl1zb5/macTU/EPo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790704713; c=relaxed/simple; bh=xhMnY8P3fAJuW7gQqQ0qb7YT+JEIYP+2o3RbxdirnqM=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=m3Kwy0PXDs/X70rZQrAKD2zsUiHanycBNi23+F3p51J5/J0uYFolgRltBW8NDB5eQ3kbVK89E0hnDItjVZ0uqO6jTgXFq2URyU7y6X9tsT4yxGNbLg1pvGjvJU/ijYLtA5g1G959hZOHfGmo/y2uxhKbQmikSN2MmPI8Lq8zR3U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ES24bieo; 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="ES24bieo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9A7B31F00893; Tue, 29 Sep 2026 17:58:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790704712; bh=0ytK01UUqKtotZZ62Ic77OTRq9P25Gej53iA0+pPsT4=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=ES24bieoPKbsUbWOs74PnIlycqVArVt4vd3DF+ZCypQue6GN5PjrAcTXtmw9nPcXk xK9/bVtNW2cuPvG1aur6VBVVDE+bedSl5xQt/U26tifGnZObliofAbqMu+U4PvU0iZ v5x9XMefm7bT9OP9dP2fpQhBvhM+nVWhqt8gQJ5nhNBMjpLicOvQqHsdB/CMVBB4t6 VZUgJIcFq2E4GDhrV/jbo3cyib+3eC+VWAQrZOy6D8jt32N1il4QOzKZBpEF6l14Co UqCgw0okDbPJxB1FY8YRy7jYmq7cAxpGLbklG/QX0rL6oqzv9Eg2Ag0Y11fRK5ZUmV mmaTQtypgKfhQ== From: Andreas Hindborg Date: Tue, 29 Sep 2026 19:56:49 +0200 Subject: [PATCH v3 2/3] rust: add a wrapper for the `nr_online_nodes` C function Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260929-cpu-helpers-v3-2-e968ce5ee613@kernel.org> References: <20260929-cpu-helpers-v3-0-e968ce5ee613@kernel.org> In-Reply-To: <20260929-cpu-helpers-v3-0-e968ce5ee613@kernel.org> To: Miguel Ojeda , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Daniel Almeida , Tamir Duberstein , Alexandre Courbot , =?utf-8?q?Onur_=C3=96zkan?= , Thomas Gleixner , Peter Zijlstra , Lorenzo Stoakes , Vlastimil Babka , "Liam R. Howlett" , Uladzislau Rezki Cc: linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1702; i=a.hindborg@kernel.org; h=from:subject:message-id; bh=xhMnY8P3fAJuW7gQqQ0qb7YT+JEIYP+2o3RbxdirnqM=; b=owEBbQKS/ZANAwAKAfpQKQiqxb3QAcsmYgBqu/wbJU1VjOLSQUJRFAJPECJd9/FEeP2M0S5Tx WBH+M9JQVaJAjMEAAEKAB0WIQRXitnI2WZ2JirAaob6UCkIqsW90AUCarv8GwAKCRD6UCkIqsW9 0PNZD/93QHc2dQpsnskLYOkLwRJiakxNnEwwECD3e4d+NbMPkkhBiO62Q0IYTuU9DWBtQWFM7OS XZFhG4dG6RkDAbKKSCXyTWKHAqedTecqoXNQFBsBzdQqNWi9AFV4lzGeGD7N7ZAN2KIGzQbOuAO 89yllTo7nrhTe/4vFlRhhLmTHRNTXNAzjHFTf/OYWdnXJ1QRXSAYMTqfOQbVJ8EbZBoAQUqltmR P9K67rKyK23SIMAiqfv9lT/HSN3qZI+4FjXLqxubvJNPOvopyFyjsTxJ8yi32dSwr8jls2vlwgq k0Uli9SljxMLU5ItkqvveWxDiAzVJ2tAOpc0DiFr3jBbWb/UBVO+rrww27m5irvFPbUXHhhahlA m8su+asrf5X7Um7OoE6PA2TNL+cFVSFxhfXlcsCa0veHMN0X5LbHYMoTrlvagxftuPxGRUvrg4z QC8xZo4BiS2I3w0KG73nOcXLplL2OVK3J6bBhw14D0QwMG6qeu16cuhY6v3Yvs21M7HPhOrD+T6 R2sWFf8V65ykyw0qSQDOBBoMv9TlFeLf0LhVLc3lPI/9uLnz1OE8TK4Eu4hhBrOdOUsRHY+4+gV SVIbV4BtWvf7IvUBn8XOzO8+kv78UcciHUHjnb44e6Fxk+SMp8XDWR/2CeLN+XhF8DliFJJ2SkG AN1d3qkXHEpKqMA== X-Developer-Key: i=a.hindborg@kernel.org; a=openpgp; fpr=3108C10F46872E248D1FB221376EB100563EF7A7 This function returns the number of online NUMA nodes. The wrapper is needed by the Rust null block driver. Signed-off-by: Andreas Hindborg --- rust/kernel/lib.rs | 1 + rust/kernel/numa.rs | 29 +++++++++++++++++++++++++++++ 2 files changed, 30 insertions(+) diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 4d5c96ddc49c..a7b1c9cf454f 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -105,6 +105,7 @@ #[cfg(CONFIG_NET)] pub mod net; pub mod num; +pub mod numa; pub mod of; #[cfg(CONFIG_PM_OPP)] pub mod opp; diff --git a/rust/kernel/numa.rs b/rust/kernel/numa.rs new file mode 100644 index 000000000000..164e622d325f --- /dev/null +++ b/rust/kernel/numa.rs @@ -0,0 +1,29 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! NUMA topology utilities. +//! +//! C header: [`include/linux/nodemask.h`](srctree/include/linux/nodemask.h) + +use crate::bindings; +#[cfg(CONFIG_NUMA)] +use crate::sync::atomic::{ + Atomic, + Relaxed, // +}; + +/// Returns the number of online NUMA nodes. +#[inline] +pub fn num_online_nodes() -> u32 { + #[cfg(CONFIG_NUMA)] + { + // SAFETY: `nr_online_nodes` is a global variable that is valid for the lifetime of the + // kernel. The C side updates it with plain writes during node hotplug and reads it with + // plain reads. A relaxed load is the Rust equivalent of `READ_ONCE()`, which is the best + // we can do on the reader side. + unsafe { Atomic::from_ptr(&raw mut bindings::nr_online_nodes) }.load(Relaxed) + } + #[cfg(not(CONFIG_NUMA))] + { + bindings::nr_online_nodes + } +} -- 2.54.0