From nobody Sat Feb 7 21:20:38 2026 Received: from mail-wm1-f74.google.com (mail-wm1-f74.google.com [209.85.128.74]) (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 C312E3385A2 for ; Tue, 21 Oct 2025 13:33:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761053601; cv=none; b=jKKlpj869YTLp70H/fJLZmW9u8K57Fo9Pzb8HlcmBJ3gCEQr68nYQxdkSuqLcayGoQnO21Kae60JGTlC/MoWhSMOJDtB0lwJupKbmY0oh9gALVlft/w0IoYc6drptCweZADtcX2iV9Kq8PGHs4y6UspP+jifZtoCP6ezoLg3/84= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761053601; c=relaxed/simple; bh=y0H0co/pGG3mnaoefgv7jJBWHvIIQnYFtiVxMl2tyu0=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=kBmwJoQ1m92x3gnauH74uKWpPwtybDGtG4QkFSHf/qysKm9F1S0lr5C232nObAIXG0LvCwEp9L97iX4rwVSRhp5IXEowBR1KclLw09UrwxEMmPbDRoq/g64g4BHGO5MbKVUeeVJ0EnB8NOCzKoZNo1VhJMDY1pWv/WFhJzwOQL0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--aliceryhl.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=u5JxU01q; arc=none smtp.client-ip=209.85.128.74 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--aliceryhl.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="u5JxU01q" Received: by mail-wm1-f74.google.com with SMTP id 5b1f17b1804b1-47114d373d5so53876285e9.1 for ; Tue, 21 Oct 2025 06:33:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1761053594; x=1761658394; 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=YusvqkwYLWumMyM3OygPRZKhF9bgc4APSkdbz1xg4sY=; b=u5JxU01qQxZ96FXpXlTJhlS75taT+NXHliWBZxEjklSJN1fQ0oz7csPPOO6zGpXVb+ 153+5dHkGdOnPL5ccH+dOwzQlVTBl/2HY3eL9D2sztCre3d/ytjJYKCGzNZk40sCG6L9 A1vkQFysHIgD+cuwg4ebDMsc8wUnsM6G4eIc0186Gxzb6sIalfmuyyCX3i6JrGz6PPhk 8iJwl2iSWRE6rxf8mKhlDyznNdPkc+izrhK/m+LO9RHXNHVQKuUApNRYHBap3BX2nBQu i16Uxh5CZ9Xu32OjuLhvsqNI2aZAhw4ntT10QLrI2srN7BQIuHGGCxgzqc3KjaEeGccG nRqg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761053594; x=1761658394; 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=YusvqkwYLWumMyM3OygPRZKhF9bgc4APSkdbz1xg4sY=; b=oklLt3N0dZ+LVPnwH+87pNWH4Q90pKhxOpYh7iU16ygMKegcMxehzpx11GngvSUVxb ZN5RNpD8KqkehtvomhiVW9rZOuJ95nEUU2pxuv9YHK83sFF0SnXiYTo4CvvZy21fWo7y hvpE1ipjAx/+p2jncLawlg65vAfAP3NVLwSwrBI7enN4qcs3GSO7iMFWA/FBzh1mu0T6 d/c04OUFD70r1mR0NFpLq170he8ucdNUG2C4NVW3JBMU4HVQQtq82qvB3MmPa+z2PELg H8sb8DL5ujqmArO212cpiLMqVV9WnEtu1lrI4yDSHdw9/TQ9/dGg+tB4c5L8tmeeN0kk AV6A== X-Forwarded-Encrypted: i=1; AJvYcCUofQZseeROuepJi8rk56z5ssPibF7Oz28F7LZv3m9dRqKjOswvXHVEC67bhHmx6AiDbvZBHjplgIL6kt0=@vger.kernel.org X-Gm-Message-State: AOJu0Yz5CZIr29nvKk9UXUwHh7Tm/lVBPxPFqLeRwZ6KijFL2OYp/g6m LiuoAzrbIug7f2hYjolL02PQtlQL0N6tRGUPuzFxGwiTrcjoy0VVITtUwbpLMdMYn70fR4TEc0Y cchOefODZ/TxKNAN5bg== X-Google-Smtp-Source: AGHT+IGHAgnRN/r9kkpyIgetmO5A2D9wd+5oaqIK8kJ6Puo5wRwP5Luw9i0GPB6EuIZssrvr5wxVUNGHB3+wWF4= X-Received: from wmbz7.prod.google.com ([2002:a05:600c:c087:b0:45f:2306:167]) (user=aliceryhl job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:468d:b0:45f:28d2:bd38 with SMTP id 5b1f17b1804b1-471178b14acmr121528965e9.18.1761053594119; Tue, 21 Oct 2025 06:33:14 -0700 (PDT) Date: Tue, 21 Oct 2025 13:32:43 +0000 In-Reply-To: <20251021-binder-bitmap-v2-0-e652d172c62b@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251021-binder-bitmap-v2-0-e652d172c62b@google.com> X-Developer-Key: i=aliceryhl@google.com; a=openpgp; fpr=49F6C1FAA74960F43A5B86A1EE7A392FDE96209F X-Developer-Signature: v=1; a=openpgp-sha256; l=2617; i=aliceryhl@google.com; h=from:subject:message-id; bh=y0H0co/pGG3mnaoefgv7jJBWHvIIQnYFtiVxMl2tyu0=; b=owEBbQKS/ZANAwAKAQRYvu5YxjlGAcsmYgBo94uX1NMWifM6CkoHtyygykkIM1ifibZQp3rD/ xyR7Hgs+wCJAjMEAAEKAB0WIQSDkqKUTWQHCvFIvbIEWL7uWMY5RgUCaPeLlwAKCRAEWL7uWMY5 RozgD/9XaOkDjMN8jCzn0IHApKOCYXGttdJuj7aYLxaz/Khss34iJS7KOd2qxRyPVUIM5wlmOcj mg2vmqlTwRxfBq/FfVWt3DCghKKjzdiBXyhDjpT4OteR0Qai99wAl//XjLolq+aTApMALai9vEN eLVb+YoikoehilUP0p6h/V0E2SdFyB6RMnYCNJX5RFRcAG0+GmlT+WzjRD+zIh7rWx/fRdns1yz ru2urA5bBSV1xnqxDsr1S8p3C2riKpnVy5nXtuUYibtYzREZcJn5/N+VMf1+Jx1wB9vN10vlBq3 +oHDOubkLPqu641tBIR0FAbX9mAE9HVdi/zq3Qc6jRhcbqohmgsIqkM/7hm6gdhQSpHu2KpVb6G MQlpW7nOEbVEKTEu/rl/YhHZImzrEzccGZtZbGy9hNRuljc6cKBPqd5HIrpfCysRw8b/NISJdKR Xi+B3rhADaEnyotWXyaB0WlzRVfse4SpSxDS3GMyZ5zPAcPQPGqjBeVZOR3HZDONv1LhL/aKy9J nI5IfG2G3T3KkcdkPIfXI99Y3PbecAqe1FFIz+QiiUJeQ2bb4KhaliyVNOu4cEeJVxqkBm7ue+z 7pnoHkrakBfWQrDqFYwHjkRK8l0QW6YUD5S0EVWon/HwAAw1N5ujZ37AuEhWRpQnV5t/qGyQ8Mn n40886pW/I9QwGw== X-Mailer: b4 0.14.2 Message-ID: <20251021-binder-bitmap-v2-1-e652d172c62b@google.com> Subject: [PATCH v2 1/5] rust: bitmap: add MAX_LEN and NO_ALLOC_MAX_LEN constants From: Alice Ryhl To: Greg Kroah-Hartman , Yury Norov Cc: "=?utf-8?q?Arve_Hj=C3=B8nnev=C3=A5g?=" , Todd Kjos , Martijn Coenen , Joel Fernandes , Christian Brauner , Carlos Llamas , Suren Baghdasaryan , Burak Emir , Miguel Ojeda , Boqun Feng , Gary Guo , "=?utf-8?q?Bj=C3=B6rn_Roy_Baron?=" , Benno Lossin , Andreas Hindborg , Trevor Gross , Danilo Krummrich , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Alice Ryhl Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable To avoid hard-coding these values in drivers, define constants for them that drivers can reference. Acked-by: Danilo Krummrich Reviewed-by: Burak Emir Signed-off-by: Alice Ryhl --- rust/kernel/bitmap.rs | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/rust/kernel/bitmap.rs b/rust/kernel/bitmap.rs index aa8fc7bf06fc99865ae755d8694e4bec3dc8e7f0..15fa23b45054b9272415fcc000e= 3e3b52c74d7c1 100644 --- a/rust/kernel/bitmap.rs +++ b/rust/kernel/bitmap.rs @@ -149,14 +149,14 @@ macro_rules! bitmap_assert_return { /// /// # Invariants /// -/// * `nbits` is `<=3D i32::MAX` and never changes. +/// * `nbits` is `<=3D MAX_LEN`. /// * if `nbits <=3D bindings::BITS_PER_LONG`, then `repr` is a `usize`. /// * otherwise, `repr` holds a non-null pointer to an initialized /// array of `unsigned long` that is large enough to hold `nbits` bits. pub struct BitmapVec { /// Representation of bitmap. repr: BitmapRepr, - /// Length of this bitmap. Must be `<=3D i32::MAX`. + /// Length of this bitmap. Must be `<=3D MAX_LEN`. nbits: usize, } =20 @@ -226,10 +226,16 @@ fn drop(&mut self) { } =20 impl BitmapVec { + /// The maximum possible length of a `BitmapVec`. + pub const MAX_LEN: usize =3D i32::MAX as usize; + + /// The maximum length that avoids allocating. + pub const NO_ALLOC_MAX_LEN: usize =3D BITS_PER_LONG; + /// Constructs a new [`BitmapVec`]. /// /// Fails with [`AllocError`] when the [`BitmapVec`] could not be allo= cated. This - /// includes the case when `nbits` is greater than `i32::MAX`. + /// includes the case when `nbits` is greater than `MAX_LEN`. #[inline] pub fn new(nbits: usize, flags: Flags) -> Result { if nbits <=3D BITS_PER_LONG { @@ -238,11 +244,11 @@ pub fn new(nbits: usize, flags: Flags) -> Result { nbits, }); } - if nbits > i32::MAX.try_into().unwrap() { + if nbits > Self::MAX_LEN { return Err(AllocError); } let nbits_u32 =3D u32::try_from(nbits).unwrap(); - // SAFETY: `BITS_PER_LONG < nbits` and `nbits <=3D i32::MAX`. + // SAFETY: `BITS_PER_LONG < nbits` and `nbits <=3D MAX_LEN`. let ptr =3D unsafe { bindings::bitmap_zalloc(nbits_u32, flags.as_r= aw()) }; let ptr =3D NonNull::new(ptr).ok_or(AllocError)?; // INVARIANT: `ptr` returned by C `bitmap_zalloc` and `nbits` chec= ked. --=20 2.51.0.869.ge66316f041-goog