From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=79.135.106.111 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792510297; b=O9wkM7OL8MBkEpPpY1Du8syy8eSAP/frY888k4wRqcLr0bKfPBWFUv4Vw0n8RtNTIXkI O1xEUjnUQ7iJBrWkRTT5373nkXW38Y1Zhp4w/9qXOzTrjRyevaWYVeoHaYTtTk3DjLjAv L37wJGM/aRdB67MYsBmyVNZfCEfaA0w4hrhEyCRr4vpzo2/K200zIU9aJn2GksEkGnUVr qZF7yqhcSazjTaJeS4m/+BQb8Ug3fBVr2Cpt9N36qTTQsGAg54JZP23esNKgsY9RvAPPd CHB+u/r/HyfAsMT/VInOU70Of3FSZh7UxcQ1jXyvbXOyZSzHgCRiwURb2UpLyT0yQlQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792510297; h=DMARC-Filter:DKIM-Signature:X-Pm-Submission-Id:From:To:Cc:Subject: Date:Message-ID:X-Mailer:In-Reply-To:References:MIME-Version: Content-Type:Content-Transfer-Encoding; bh=ozMRWgTmERbTm7OTdn+HlrOHvH/CkZpAs4fZ5ypYxgk=; b=J23LTKZAN9SM3tgOEslUePySYkR24Ac6xcrjf36DO28ugbut/90HwSzTTMNEx9r+jpBs eAr7lqZHurJYv7Tz4eWK9rE+iIOm0SCFMxE/cGglFPwmHH2fz+R69puQyTm6JKI8KWTRI +Nk3/COOJuw/DcviL+Cgw2RG1OUwQFaGA1j7WCXPX19JwMUMHM+u5tbdxRTUyK+ZFzV8s 4yaO/XvvDZljF+6gWKifkcRw0UnF6YO6NP7xvn9OkG4R+LjnnKJosWcgRF37EZ5LhGqGX nSTF5byiRiYfDC0xF/A3KS2pvdvaFUbMOhToLDPqBHw/3xqKQLQnNqQcYe0voLWHQYg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=onurozkan.dev; spf=pass smtp.mailfrom=onurozkan.dev; dkim=pass header.d=onurozkan.dev header.i=@onurozkan.dev header.a=rsa-sha256 header.s=protonmail2 header.b=ftu16uXZ; arc=none smtp.remote-ip=79.135.106.111 Received: from mail-106111.protonmail.ch (mail-106111.protonmail.ch [79.135.106.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B5B82606A335; Tue, 20 Oct 2026 15:31:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org B5B82606A335 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=onurozkan.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=onurozkan.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=onurozkan.dev header.i=@onurozkan.dev header.a=rsa-sha256 header.s=protonmail2 header.b=ftu16uXZ DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=onurozkan.dev; s=protonmail2; t=1792510294; x=1792769494; bh=ozMRWgTmERbTm7OTdn+HlrOHvH/CkZpAs4fZ5ypYxgk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References:From:To: Cc:Date:Subject:Reply-To:Feedback-ID:Message-ID:BIMI-Selector; b=ftu16uXZHrnYCNUW+rKuptAMdPJUPvl5lOooz/n8/BGbP95mB2vmjxUKkB1G2yIwS wmv99Uvb3Icx1D/nWvuL5ZkK2TAS2yB1bHsCBW/uR8ac/QkpxzFexKGU5Nu6ZcPw0+ 5OMacfqM8qJqSLtsoDKiT1TMXBTSEKMGEPO4ETj+vv8rv9pghazpsK20XRtW6qaM17 8N+h1QKnKnM3pZTEz+8BrtzCkpV0sul4U9+k4Op7pRW0QxyxyejTO+fIy2OEcR8Izi 9r7k+9s3nPzM6MAm2XLkTR2ppDP9nMGbzj3Zgrt5P8mXdTosnJyMIvOlJGrruF3Cq1 rA/WneWgSBCuQ== X-Pm-Submission-Id: 4j8Gbf4TMCz2ScPL From: =?UTF-8?q?Onur=20=C3=96zkan?= To: rust-for-linux@vger.kernel.org Cc: lossin@kernel.org, lyude@redhat.com, ojeda@kernel.org, alex.gaynor@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, a.hindborg@kernel.org, aliceryhl@google.com, tmgross@umich.edu, dakr@kernel.org, peterz@infradead.org, mingo@redhat.com, will@kernel.org, longman@redhat.com, felipe_life@live.com, daniel@sedlak.dev, daniel.almeida@collabora.com, thomas.hellstrom@linux.intel.com, linux-kernel@vger.kernel.org, =?UTF-8?q?Onur=20=C3=96zkan?= Subject: [PATCH v13 3/7] rust: implement Class for ww_class support Date: Tue, 20 Oct 2026 18:29:39 +0300 Message-ID: <20261020153112.299745-4-work@onurozkan.dev> X-Mailer: git-send-email 2.51.2 In-Reply-To: <20261020153112.299745-1-work@onurozkan.dev> References: <20261020153112.299745-1-work@onurozkan.dev> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Adds the Class type, the first step in supporting ww_mutex in Rust. Class represents ww_class, used for deadlock avoidance for supporting both wait-die and wound-wait semantics. Also adds the define_ww_class and define_wd_class macros for safely declaring static instances. Reviewed-by: Gary Guo Reviewed-by: Alice Ryhl Reviewed-by: Daniel Almeida Signed-off-by: Onur Özkan --- rust/kernel/sync/lock.rs | 1 + rust/kernel/sync/lock/ww_mutex.rs | 7 ++ rust/kernel/sync/lock/ww_mutex/class.rs | 130 ++++++++++++++++++++++++ 3 files changed, 138 insertions(+) create mode 100644 rust/kernel/sync/lock/ww_mutex.rs create mode 100644 rust/kernel/sync/lock/ww_mutex/class.rs diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs index 10b6b5e9b024f..f509250822c55 100644 --- a/rust/kernel/sync/lock.rs +++ b/rust/kernel/sync/lock.rs @@ -15,6 +15,7 @@ pub mod mutex; pub mod spinlock; +pub mod ww_mutex; pub(super) mod global; pub use global::{GlobalGuard, GlobalLock, GlobalLockBackend, GlobalLockedBy}; diff --git a/rust/kernel/sync/lock/ww_mutex.rs b/rust/kernel/sync/lock/ww_mutex.rs new file mode 100644 index 0000000000000..727c51cc73af8 --- /dev/null +++ b/rust/kernel/sync/lock/ww_mutex.rs @@ -0,0 +1,7 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Rust abstractions for the kernel's wound-wait locking primitives. + +pub use class::Class; + +mod class; diff --git a/rust/kernel/sync/lock/ww_mutex/class.rs b/rust/kernel/sync/lock/ww_mutex/class.rs new file mode 100644 index 0000000000000..36c7e87d72660 --- /dev/null +++ b/rust/kernel/sync/lock/ww_mutex/class.rs @@ -0,0 +1,130 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Provides [`Class`] to group wound/wait mutexes to be acquired together +//! and specifies which deadlock avoidance algorithm to use (e.g., wound-wait +//! or wait-die). +//! +//! The [`define_ww_class!`] and [`define_wd_class!`] macros provide safe +//! ways to create classes. + +use crate::{ + bindings, + prelude::*, + types::Opaque, // +}; + +/// Defines a static wound-wait [`Class`]. +/// +/// # Examples +/// +/// ``` +/// use kernel::define_ww_class; +/// +/// define_ww_class!(SOME_WW_CLASS); +/// ``` +#[macro_export] +macro_rules! define_ww_class { + ($name:ident) => { + static $name: $crate::sync::lock::ww_mutex::Class = + // SAFETY: This is `static`, so address is fixed and won't move. + unsafe { + $crate::sync::lock::ww_mutex::Class::new_unpinned( + $crate::c_str!(::core::concat!(::core::stringify!($name), "_acquire")), + $crate::c_str!(::core::concat!(::core::stringify!($name), "_mutex")), + false, + ) + }; + }; +} + +/// Defines a static wait-die [`Class`]. +/// +/// # Examples +/// +/// ``` +/// use kernel::define_wd_class; +/// +/// define_wd_class!(SOME_WD_CLASS); +/// ``` +#[macro_export] +macro_rules! define_wd_class { + ($name:ident) => { + static $name: $crate::sync::lock::ww_mutex::Class = + // SAFETY: This is `static`, so address is fixed and won't move. + unsafe { + $crate::sync::lock::ww_mutex::Class::new_unpinned( + $crate::c_str!(::core::concat!(::core::stringify!($name), "_acquire")), + $crate::c_str!(::core::concat!(::core::stringify!($name), "_mutex")), + true, + ) + }; + }; +} + +/// Used to group mutexes together for deadlock avoidance. +/// +/// All mutexes that might be acquired together should use the same class. +/// +/// # Examples +/// +/// ``` +/// use kernel::{ +/// define_wd_class, +/// define_ww_class, // +/// }; +/// +/// define_ww_class!(SOME_WW_CLASS); +/// define_wd_class!(SOME_WD_CLASS); +/// +/// # Ok::<(), Error>(()) +/// ``` +#[pin_data] +#[repr(transparent)] +pub struct Class { + #[pin] + pub(super) inner: Opaque, +} + +impl Class { + /// Creates an unpinned [`Class`]. + /// + /// # Safety + /// + /// Caller must guarantee that the returned value must be pinned before + /// its first use. + #[doc(hidden)] + pub const unsafe fn new_unpinned( + acquire_name: &'static CStr, + mutex_name: &'static CStr, + is_wait_die: bool, + ) -> Self { + Class { + inner: Opaque::new(bindings::ww_class { + stamp: bindings::atomic_long_t { counter: 0 }, + acquire_name: crate::str::as_char_ptr_in_const_context(acquire_name), + mutex_name: crate::str::as_char_ptr_in_const_context(mutex_name), + is_wait_die: is_wait_die as u32, + ..pin_init::zeroed() + }), + } + } + + /// Creates a [`Class`] from a raw pointer. + /// + /// This function is intended for interoperability with C code. + /// + /// # Safety + /// + /// The caller must ensure that `ptr` points to the `inner` field of + /// [`Class`] and that it remains valid for the lifetime `'a`. + #[inline] + pub const unsafe fn from_raw<'a>(ptr: *mut bindings::ww_class) -> &'a Self { + // SAFETY: By the safety contract, `ptr` is valid to construct `Class`. + unsafe { &*ptr.cast() } + } +} + +// SAFETY: [`Class`] is immutable except for its atomic stamp. It's fine to share it across threads. +unsafe impl Sync for Class {} +// SAFETY: Doesn't hold anything thread-specific. It's safe to send to other threads. +unsafe impl Send for Class {} -- 2.51.2