From nobody Tue Dec 16 14:48:27 2025 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (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 86F512989A5 for ; Tue, 6 May 2025 01:04:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746493461; cv=none; b=rdBfYlXU7yRy4VZUG9XnD9Z5YuP5rtIrUOcBMrZ6qroF6On/4yHpmr/bMuauspZU+ExcAD19RiDOUVXwLdFNOAdxh7pibqqwV7icuv0FheJ04togNrO0k3YK7i4mS+ETq/qLG/UzWwf61Xm4nZYW25g14xNn9Ljhi83ZYgt9Ck0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746493461; c=relaxed/simple; bh=/k3Yo3khleRb+uxwsSODt3lvyFcZ63bMldnep7BhLE8=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=HGNkET8/4Rv1ayvZ6NL1JwxuWcqbkSGw15M963UdTmp5VlFdB9lys1NMG6MtplUyXVi4ymXA7AlDnRmeTvHSgwoMK9cHEuNu28eywsIb0XKNJvYX5ZWdT7eLBhdHfhZk3Y1EvzpFcublEbnd3BZPSCvEFvUvwig4fgUZSpox0K0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--mmaurer.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=z2OL1KhP; arc=none smtp.client-ip=209.85.216.74 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--mmaurer.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="z2OL1KhP" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-309c6e43a9aso7554735a91.2 for ; Mon, 05 May 2025 18:04:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1746493459; x=1747098259; 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=T8/F7HTaR1lenYv3bo9DPTN5D8KoLav+c1ChwtLfsdY=; b=z2OL1KhPrDx80f+1EzE6n1bGXnJxtn07RG6551YpXzLkwUZwy4oWlb+sV3TdKuBJ2V p36Mc8h02N7KovbbNxojEi0yRxBAAxw8KnkcXG3etQ9ezsnHUtTTf9gtpZ3XEm6rhWC4 aZtMf2OdOrL+eXm/K9380eStClgmJkNg7TX5hkQ6+mGHVQe8xKWJLsJKYPlYPdeAd0iw eKeCJ1a9lfS75SseSf6MKiJn76rgo7nQ8Oin2b1lFFsPKVP5ACMQuSq/ZlWkxqUDKZZT epKpy6x0IN6mKr2dnSgwn89+QCPKuPnJPXiFF0whDZyIzEB2tDheup3G7SNoADp7Eivi oRtQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1746493459; x=1747098259; 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=T8/F7HTaR1lenYv3bo9DPTN5D8KoLav+c1ChwtLfsdY=; b=NpqOXfebSSNGloHWw173x8ZdB43z3KoS9W/p2hIExHadD20FLz5zl7GNhv7DrW6rOd 38lqlt2+0hgDfYc224ghR8/y4Bd7uOe2FoMmITPW3WKLgFusDRJ9q05KvMoig8L5Darr W90ov5zy1PfTu1L4rFLgBd8LWw8vBadVO9GqSZV7616kShKp1+HzFu8Na/lou8XKWiTh IcS6oBzkyH28JbpuuLCEOBXt9XhRl8uCVvvt3bMKRn8In1NUh/oI44OtyOaRr9BZRuKb U98SAh4j4VQoh8CAYhqBNMBZTcK0dQ2/WhjpUw22UA3vZm1wIZvN3e6W+y3BnYxF4CtV ewUQ== X-Forwarded-Encrypted: i=1; AJvYcCUPZhgICupPQl4kwAfJ7WrC/91U4vQ1dsH2289vaHin9GhdOYktEkzgJcfjiZ01L9+Z4MqIkgbMcHaflGo=@vger.kernel.org X-Gm-Message-State: AOJu0Yyv6YjD3CpGZnZg4n2KnIlFTQfHoZolNElczh2gt+M9ftuTY0fN RvRueFZoJr9TR+jwE9JJ1/0VdCjyqCzqUEnRcNdOYgAXHqb2V7q9ShcXyp4M9Y9dXRuqdk03gqW n2TbO0Q== X-Google-Smtp-Source: AGHT+IHgCB4fVw2Q+BCHF9mjG2qX9mTc3bFJdne7hHQKkSQzvpo0cj2msg14MbGPMOt6w+ocQVkp0Nu6Jimf X-Received: from pjbtb7.prod.google.com ([2002:a17:90b:53c7:b0:301:2679:9d9]) (user=mmaurer job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:56c8:b0:2ee:8ea0:6b9c with SMTP id 98e67ed59e1d1-30a7c0806e9mr2600361a91.12.1746493458765; Mon, 05 May 2025 18:04:18 -0700 (PDT) Date: Tue, 06 May 2025 01:04:14 +0000 In-Reply-To: <20250506-debugfs-rust-attach-v2-0-c6f88be3890a@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250506-debugfs-rust-attach-v2-0-c6f88be3890a@google.com> X-Developer-Key: i=mmaurer@google.com; a=ed25519; pk=2Ezhl7+fEjTOMVFpplDeak2AdQ8cjJieLRVJdNzrW+E= X-Developer-Signature: v=1; a=ed25519-sha256; t=1746493453; l=6273; i=mmaurer@google.com; s=20250429; h=from:subject:message-id; bh=/k3Yo3khleRb+uxwsSODt3lvyFcZ63bMldnep7BhLE8=; b=SCAhhh32aNFPz7cmDQI4C3sCPKGhapQWcPJVBsZsIU8GMTMEXvfsAyPFbxDsscRgcSw/LU+F5 c2ytLqN7pIQDKauKD6eB5tfJrsfjzMQDWKo3KQoXIHQzjSAPgRZOPY5 X-Mailer: b4 0.14.2 Message-ID: <20250506-debugfs-rust-attach-v2-2-c6f88be3890a@google.com> Subject: [PATCH WIP v2 2/2] rust: debugfs: Extend sample to use attached data From: Matthew Maurer To: Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , "=?utf-8?q?Bj=C3=B6rn_Roy_Baron?=" , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Sami Tolvanen , Timur Tabi Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Matthew Maurer Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Demonstrates how to attach data/handles needed for implementing DebugFS file to a directory. Signed-off-by: Matthew Maurer --- samples/rust/rust_debugfs.rs | 110 +++++++++++++++++++++++++++++++++++++++= ++-- 1 file changed, 106 insertions(+), 4 deletions(-) diff --git a/samples/rust/rust_debugfs.rs b/samples/rust/rust_debugfs.rs index a4b17c8241330b2f6caf8f17a5b2366138de6ced..efaca1b140f710fcc7d0467e9b0= 0e02a69c2cf55 100644 --- a/samples/rust/rust_debugfs.rs +++ b/samples/rust/rust_debugfs.rs @@ -4,11 +4,15 @@ =20 //! Sample DebugFS exporting module =20 +use core::fmt; +use core::fmt::{Display, Formatter}; use core::mem::{forget, ManuallyDrop}; use core::sync::atomic::{AtomicU32, Ordering}; use kernel::c_str; -use kernel::debugfs::Dir; +use kernel::debugfs::{BoundDir, Dir, Values}; +use kernel::new_mutex; use kernel::prelude::*; +use kernel::sync::{Arc, Mutex}; =20 module! { type: RustDebugFs, @@ -21,7 +25,89 @@ struct RustDebugFs { // As we only hold this for drop effect (to remove the directory) we h= ave a leading underscore // to indicate to the compiler that we don't expect to use this field = directly. - _debugfs: Dir<'static>, + _debugfs: Pin>>, +} + +struct Composite { + major: u32, + minor: u32, +} + +struct Record { + name: &'static CStr, + size: usize, + stride: usize, +} + +struct Backing { + simple: u32, + composite: Composite, + custom: u32, + many: KVec, + atomic: AtomicU32, + locked: Arc>, +} + +impl Display for Composite { + fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result { + write!(f, "{}.{}", self.major, self.minor) + } +} + +impl Backing { + fn new() -> Result { + let mut many =3D KVec::new(); + many.push( + Record { + name: c_str!("foo"), + size: 1, + stride: 2, + }, + GFP_KERNEL, + )?; + many.push( + Record { + name: c_str!("bar"), + size: 3, + stride: 4, + }, + GFP_KERNEL, + )?; + Ok(Self { + simple: 10, + composite: Composite { major: 1, minor: 2 }, + custom: 37, + many, + atomic: AtomicU32::new(7), + locked: Arc::pin_init(new_mutex!(0), GFP_KERNEL)?, + }) + } + + fn build<'a>(&'a self, root: BoundDir<'a>) { + // Just prints out the number in the field + forget(root.display_file(c_str!("simple"), &self.simple)); + // Uses the custom display implementation to print major.minor + forget(root.display_file(c_str!("composite"), &self.composite)); + // Uses the custom hook print the number in 0-padded hex with some= decorations. + forget(root.fmt_file(c_str!("custom"), &self.custom, &|custom, f| { + writeln!(f, "Foo! {:#010x} Bar!", custom) + })); + // Creates a directory for every record in the list, named the nam= e of the item, with files + // for each attribute. + for record in self.many.iter() { + let dir =3D ManuallyDrop::new(root.subdir(record.name)); + forget(dir.display_file(c_str!("size"), &record.size)); + forget(dir.display_file(c_str!("stride"), &record.stride)); + } + // Access the attached atomic via `.load()` + forget(root.fmt_file(c_str!("atomic"), &self.atomic, &|atomic, f| { + writeln!(f, "{}", atomic.load(Ordering::Relaxed)) + })); + // Access the attached mutex-guarded data via `.lock()` + forget(root.fmt_file(c_str!("locked"), &self.locked, &|locked, f| { + writeln!(f, "{}", *locked.lock()) + })); + } } =20 static EXAMPLE: AtomicU32 =3D AtomicU32::new(8); @@ -29,13 +115,13 @@ struct RustDebugFs { impl kernel::Module for RustDebugFs { fn init(_this: &'static ThisModule) -> Result { // Create a debugfs directory in the root of the filesystem called= "sample_debugfs". - let debugfs =3D Dir::new(c_str!("sample_debugfs")); + let root =3D Dir::new(c_str!("sample_debugfs")); =20 { // Create a subdirectory, so "sample_debugfs/subdir" now exist= s. // We wrap it in `ManuallyDrop` so that the subdirectory is no= t automatically discarded // at the end of the scope - it will be cleaned up when `debug= fs` is. - let sub =3D ManuallyDrop::new(debugfs.subdir(c_str!("subdir"))= ); + let sub =3D ManuallyDrop::new(root.subdir(c_str!("subdir"))); =20 // Create a single file in the subdirectory called "example" t= hat will read from the // `EXAMPLE` atomic variable. @@ -51,6 +137,22 @@ fn init(_this: &'static ThisModule) -> Result { EXAMPLE.store(10, Ordering::Relaxed); // Now, "sample_debugfs/subdir/example" will print "Reading atomic= : 10\n" when read. =20 + // We can also attach data scoped to our root directory + let backing =3D Backing::new()?; + // Grab a refcount pointing to the locked data + let locked =3D backing.locked.clone(); + let debugfs =3D KBox::pin_init(Values::attach(backing, root), GFP_= KERNEL)?; + + // Once it's attached, we can invoke `Backing::build` to create th= e relevant files: + debugfs.as_ref().build(Backing::build); + + // We can still access read-only references the contents of the at= tached values. If the + // values allow interior mutability, like atomics, this lets us st= ill change them: + debugfs.as_ref().atomic.store(8, Ordering::Relaxed); + + // If we attached refcounted data, we can use an external handle t= o access it + *locked.lock() =3D 42; + // Save the root debugfs directory we created to our module object= . It will be // automatically cleaned up when our module is unloaded because dr= opping the module object // will drop the `Dir` handle. The base directory, the subdirector= y, and the file will all --=20 2.49.0.967.g6a0df3ecc3-goog