From nobody Sun May 24 21:37:39 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9D563311C36; Thu, 21 May 2026 08:54:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779353665; cv=none; b=Y3l/AEsQj4B/iznmkKtK2R4Qe0Jdw2F893ctNwKbP1a+Bhc0uu4/imfoVlEE1jXuH2fKQFyYLRVPoplxWbflPc6fy9sLuh/e0gAEQ4GGWxFVisBRRqs5tCVunqlkTCLs8qPb7MBHb9qUnmVSzRQo4BHrTddfHjpIciQbXNcE6zo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779353665; c=relaxed/simple; bh=FTgko1NThfwlhElxnXPhKt3juV5gU4QGVhTziOsckg8=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=ibcZnxNT7va4Uri+L6GIMNn33dy5VSIT3abZflVKt4dHujnO3tdrj4F2A7CsNC4/Ksf1tZDj+leXaCkrFznDHPJcdkcLPNg/XyuwJ6bZ2vGu8EQLTmsFSoOc5EJ44TozYhqdKIrpMzynnHu5l0XKb7S0QS2Wf1Q/noCMC7EbZvA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nP6VXUgl; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nP6VXUgl" Received: by smtp.kernel.org (Postfix) with ESMTPS id 59373C2BCB9; Thu, 21 May 2026 08:54:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1779353665; bh=FTgko1NThfwlhElxnXPhKt3juV5gU4QGVhTziOsckg8=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=nP6VXUglBi7wmfdZ5csvFlyQylmTk3qlubtgoBLSpSiYhA6sujta6a1TNcYjsoS51 2L8wtABi5bdK+ioOu/VBgi5FJ+iat3auUcHI/piKwzZRVqMFabYh4pemTcNOfBGWUh C6vourFW/puihTCuzGEyN4VpyZQOcL4aywT3W2hYFWhX7nB+5S1w9izLpMm34jIBIW ump/km69utEdpy10r4OddIYQc+uuA8m3Dy/tAIfWGisXThdR4HG2bDtPkgAGyWw+1r kKQmtww1VCGC1MOTToxK/4ff0/fLqQLYgkI7+RMRcu1w8FO8es4kSl/Dr36lwTmZAP QX8Kjgi+qYyPQ== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 44997CD5BA4; Thu, 21 May 2026 08:54:25 +0000 (UTC) From: Aakash Bollineni via B4 Relay Date: Thu, 21 May 2026 14:24:21 +0530 Subject: [PATCH v7 1/3] rust: helpers: add workqueue helpers 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: quoted-printable Message-Id: <20260521-workqueue-v5-sent-v7-1-fb4b4dde35ec@multicorewareinc.com> References: <20260521-workqueue-v5-sent-v7-0-fb4b4dde35ec@multicorewareinc.com> In-Reply-To: <20260521-workqueue-v5-sent-v7-0-fb4b4dde35ec@multicorewareinc.com> 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 Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Aakash Bollineni X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1779353663; l=1654; i=aakash.bollineni@multicorewareinc.com; s=20260402; h=from:subject:message-id; bh=N914P+plvR5IEkLzAqjpGBi8jBApqGMRlOfflBmXQOs=; b=qn9w0ARO1aI0WSl7IXPulLtVyFbMCXlwUF/fPTD2ejSjRDQ8l3YnwcRZmgfFWM1LUfWvf77L8 n9vYpnG4ln/DrbRINhSzGE2H0NsasdNo0HI0DrWgRmKCEiXOg/qGz+7 X-Developer-Key: i=aakash.bollineni@multicorewareinc.com; a=ed25519; pk=r3Gonl+2k+8RozN9U/XwfICQdnRlAcLeeAfsExmurdE= X-Endpoint-Received: by B4 Relay for aakash.bollineni@multicorewareinc.com/20260402 with auth_id=711 X-Original-From: Aakash Bollineni Reply-To: aakash.bollineni@multicorewareinc.com From: Aakash Bollineni Add C helpers for work_pending, cancel_work_sync, and cancel_delayed_work_sync to bridge the Rust workqueue abstraction with the kernel's C workqueue macros. Additionally, add a robust initialization helper for delayed_work that ensures correct timer (delayed_work_timer_fn) and lockdep setup in a single pass, avoiding redundant initialization. Signed-off-by: Aakash Bollineni --- rust/helpers/workqueue.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/rust/helpers/workqueue.c b/rust/helpers/workqueue.c index ce1c3a5b2150..ef18d79f95be 100644 --- a/rust/helpers/workqueue.c +++ b/rust/helpers/workqueue.c @@ -14,3 +14,30 @@ __rust_helper void rust_helper_init_work_with_key(struct= work_struct *work, INIT_LIST_HEAD(&work->entry); work->func =3D func; } + +__rust_helper bool rust_helper_work_pending(struct work_struct *work) +{ + return work_pending(work); +} + +__rust_helper bool rust_helper_cancel_work_sync(struct work_struct *work) +{ + return cancel_work_sync(work); +} + +__rust_helper bool rust_helper_cancel_delayed_work_sync(struct delayed_wor= k *dwork) +{ + return cancel_delayed_work_sync(dwork); +} + +__rust_helper void rust_helper_init_delayed_work(struct delayed_work *dwor= k, + work_func_t func, + const char *name, + struct lock_class_key *key, + const char *tname, + struct lock_class_key *tkey) +{ + rust_helper_init_work_with_key(&dwork->work, func, false, name, key); + timer_init_key(&dwork->timer, delayed_work_timer_fn, TIMER_IRQSAFE, tname= , tkey); +} + --=20 2.43.0 From nobody Sun May 24 21:37:39 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9D4C330FC34; Thu, 21 May 2026 08:54:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779353665; cv=none; b=FeNtZ3fEPVX6AFjbV0MpGJxYc5/p48T4B8bsL8BRt7/CmBdpExqCH+dZcHghzxc/H3Rwf9qGGA14w6DP70Fg6C+qVSHn/tS4rOqBhp/ihiuYe8ucwbsNaUQDjwtilQQuU5C2TDrwAsRF5OIDWUMlGYE40oCwSE5vs/nP5BPucR4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779353665; c=relaxed/simple; bh=/0fy5Y0Gi7YRho17BNzewwCIr/QCOHUqMZvzgUFW/Uo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; 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Thu, 21 May 2026 08:54:25 +0000 (UTC) From: Aakash Bollineni via B4 Relay Date: Thu, 21 May 2026 14:24:22 +0530 Subject: [PATCH v7 2/3] rust: workqueue: add safe cancellation and status methods 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: quoted-printable Message-Id: <20260521-workqueue-v5-sent-v7-2-fb4b4dde35ec@multicorewareinc.com> References: <20260521-workqueue-v5-sent-v7-0-fb4b4dde35ec@multicorewareinc.com> In-Reply-To: <20260521-workqueue-v5-sent-v7-0-fb4b4dde35ec@multicorewareinc.com> 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 Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Aakash Bollineni X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1779353663; l=24380; i=aakash.bollineni@multicorewareinc.com; s=20260402; h=from:subject:message-id; bh=UzNlgN1mZIUSrhWmCtyyBUkaxMPUJQz14AvACbKDO7s=; b=7khziqX/SelfZtRFXLV/4qVVbCh7SrbIiuSXr4MqhPPuXwWD/XDqRBGDo25T52E3Kp3NX2V0S 9VLj8PT5vMtCkragPT+HfHmXHyOxKIg1bc5sgIfGytY8NbhcLZK/sm7 X-Developer-Key: i=aakash.bollineni@multicorewareinc.com; a=ed25519; pk=r3Gonl+2k+8RozN9U/XwfICQdnRlAcLeeAfsExmurdE= X-Endpoint-Received: by B4 Relay for aakash.bollineni@multicorewareinc.com/20260402 with auth_id=711 X-Original-From: Aakash Bollineni Reply-To: aakash.bollineni@multicorewareinc.com From: Aakash Bollineni Modernize the Rust workqueue by adding methods for status checking and cancellation of work and delayed work items. Specifically, this patch adds: - is_pending(): Returns true if the work item is currently enqueued. - cancel(): Attempts to cancel the work item before it runs. If successful, it reclaims and returns ownership of the original pointer (Arc/KBox). - cancel_sync(): Synchronously cancels the work item, waiting for it to finish if it's already running. Reclaims ownership if the work was pending. To support safe pointer reclamation, a new "Handle-based" model is introduced via the WorkItemPointer::reclaim method. This ensures that the "leaked" ownership from an enqueue operation is safely recovered without memory leaks. Additionally, we enforce #[repr(transparent)] on core work wrappers to ensure memory layout compatibility with C pointers and fix pointer arithmetic in the work_container_of implementation. Signed-off-by: Aakash Bollineni --- rust/kernel/workqueue.rs | 500 +++++++++++++++++++++++++++++++++++++++++++= ---- 1 file changed, 465 insertions(+), 35 deletions(-) diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs index 706e833e9702..ca29d69450b3 100644 --- a/rust/kernel/workqueue.rs +++ b/rust/kernel/workqueue.rs @@ -69,6 +69,7 @@ //! fn print_later(val: Arc) { //! let _ =3D workqueue::system().enqueue(val); //! } +//! //! # print_later(MyStruct::new(42).unwrap()); //! ``` //! @@ -127,6 +128,7 @@ //! fn print_2_later(val: Arc) { //! let _ =3D workqueue::system().enqueue::, 2>(val); //! } +//! //! # print_1_later(MyStruct::new(24, 25).unwrap()); //! # print_2_later(MyStruct::new(41, 42).unwrap()); //! ``` @@ -179,6 +181,7 @@ //! fn print_now(val: Arc) { //! let _ =3D workqueue::system().enqueue(val); //! } +//! //! # print_later(MyStruct::new(42).unwrap()); //! # print_now(MyStruct::new(42).unwrap()); //! ``` @@ -448,8 +451,26 @@ pub unsafe trait WorkItemPointer: RawWo= rkItem { /// The provided `work_struct` pointer must originate from a previous = call to [`__enqueue`] /// where the `queue_work_on` closure returned true, and the pointer m= ust still be valid. /// + /// The implementation must ensure that the pointer is reclaimed (e.g.= , via `from_raw`) + /// before calling the `run` method of the underlying [`WorkItem`]. + /// /// [`__enqueue`]: RawWorkItem::__enqueue unsafe extern "C" fn run(ptr: *mut bindings::work_struct); + + /// Reclaims ownership of the pointer from the work item. + /// + /// This is called when a work item is successfully cancelled, allowin= g the caller + /// to recover the original pointer (e.g., `Arc` or `KBox`) that was "= leaked" + /// during enqueuing. + /// + /// # Safety + /// + /// The provided `work_struct` pointer must originate from a previous = call to [`__enqueue`] + /// where the `queue_work_on` closure returned true, and the work item= must have been + /// successfully cancelled (i.e., `cancel_work` returned true). + /// + /// [`__enqueue`]: RawWorkItem::__enqueue + unsafe fn reclaim(ptr: *mut bindings::work_struct) -> Self; } =20 /// Defines the method that should be called when this work item is execut= ed. @@ -516,6 +537,175 @@ pub fn new(name: &'static CStr, key: Pin<&'static Loc= kClassKey>) -> impl PinInit }) } =20 + /// Returns whether the work item is currently pending. + /// + /// # Warning + /// + /// This method is inherently racy. A work item can be enqueued or sta= rt running + /// immediately after this check returns. Do not rely on this for corr= ectness + /// logic (e.g., as a guard for unsafe operations); use it only for de= bugging or + /// non-critical status reporting. + /// + /// # Examples + /// + /// ``` + /// # use kernel::workqueue::{self, new_work, Work, WorkItem, HasWork}; + /// # use kernel::impl_has_work; + /// # use kernel::sync::Arc; + /// + /// # #[pin_data] + /// # struct MyStruct { #[pin] work: Work } + /// + /// # impl_has_work! { impl HasWork for MyStruct { self.work } } + /// + /// # impl WorkItem for MyStruct { + /// # type Pointer =3D Arc; + /// # fn run(_this: Arc) {} + /// # } + /// + /// let my_struct =3D Arc::pin_init(pin_init!(MyStruct { + /// work <- new_work!("MyStruct::work"), + /// }), kernel::alloc::flags::GFP_KERNEL).unwrap(); + /// + /// assert!(!my_struct.work.is_pending()); + /// + /// workqueue::system().enqueue(my_struct.clone()); + /// + /// assert!(my_struct.work.is_pending()); + /// + /// # let _ =3D my_struct.work.cancel(); + /// ``` + #[inline] + pub fn is_pending(&self) -> bool { + // SAFETY: `self.work` is a valid pointer to a `work_struct`. + unsafe { bindings::work_pending(self.work.get()) } + } + + /// Cancels the work item. + /// + /// If the work item was successfully cancelled (i.e., it was pending = and had not yet + /// started running), the original pointer is reclaimed and returned. + /// + /// # Guarantees + /// + /// This method is non-blocking and may return while the work item is = still running + /// on another CPU. If it returns `None`, the work item might be about= to start, + /// is currently running, or has already finished. + /// + /// # Safety + /// + /// This is safe because ownership is only reclaimed if the kernel con= firms (via + /// `cancel_work` returning true) that the work item is no longer in a= ny queue and + /// will not be executed by the workqueue for this specific enqueue ev= ent. + /// + /// # Examples + /// + /// ``` + /// # use kernel::workqueue::{self, new_work, Work, WorkItem, HasWork}; + /// # use kernel::impl_has_work; + /// # use kernel::sync::Arc; + /// + /// # #[pin_data] + /// # struct MyStruct { #[pin] work: Work } + /// + /// # impl_has_work! { impl HasWork for MyStruct { self.work } } + /// + /// # impl WorkItem for MyStruct { + /// # type Pointer =3D Arc; + /// # fn run(_this: Arc) {} + /// # } + /// + /// let my_struct =3D Arc::pin_init(pin_init!(MyStruct { + /// work <- new_work!("MyStruct::work"), + /// }), kernel::alloc::flags::GFP_KERNEL).unwrap(); + /// + /// workqueue::system().enqueue(my_struct.clone()); + /// + /// assert!(my_struct.work.is_pending()); + /// + /// let reclaimed =3D my_struct.work.cancel(); + /// + /// assert!(reclaimed.is_some()); + /// assert!(!my_struct.work.is_pending()); + /// ``` + pub fn cancel(&self) -> Option + where + T: WorkItem, + { + let work_ptr =3D self.work.get(); + // SAFETY: `work_ptr` is a valid pointer to a `work_struct`. + if unsafe { bindings::cancel_work(work_ptr) } { + // SAFETY: The work item was successfully cancelled and is gua= ranteed not to run, + // so we can safely reclaim the ownership leaked during `enque= ue`. + Some(unsafe { T::Pointer::reclaim(work_ptr) }) + } else { + None + } + } + + /// Synchronously cancels the work item. + /// + /// This method waits for the work item to finish if it is currently r= unning. + /// If the work item was successfully cancelled from the queue, the po= inter is + /// reclaimed and returned. + /// + /// # Guarantees + /// + /// After this method returns, the work item is guaranteed to be: + /// - Not pending in any queue. + /// - Not running on any CPU. + /// + /// This makes it safe to use during teardown (e.g., driver `remove` o= r object `drop`) + /// to ensure no background tasks are accessing resources that are abo= ut to be freed. + /// + /// # Safety + /// + /// Same as [`Self::cancel`], it only reclaims ownership if the kernel= confirms the work + /// was still pending and is now removed. + /// + /// # Examples + /// + /// ``` + /// # use kernel::workqueue::{self, new_work, Work, WorkItem, HasWork}; + /// # use kernel::impl_has_work; + /// # use kernel::sync::Arc; + /// + /// # #[pin_data] + /// # struct MyStruct { #[pin] work: Work } + /// + /// # impl_has_work! { impl HasWork for MyStruct { self.work } } + /// + /// # impl WorkItem for MyStruct { + /// # type Pointer =3D Arc; + /// # fn run(_this: Arc) {} + /// # } + /// + /// let my_struct =3D Arc::pin_init(pin_init!(MyStruct { + /// work <- new_work!("MyStruct::work"), + /// }), kernel::alloc::flags::GFP_KERNEL).unwrap(); + /// + /// workqueue::system().enqueue(my_struct.clone()); + /// + /// let reclaimed =3D my_struct.work.cancel_sync(); + /// + /// assert!(reclaimed.is_some()); + /// ``` + pub fn cancel_sync(&self) -> Option + where + T: WorkItem, + { + let work_ptr =3D self.work.get(); + // SAFETY: `work_ptr` is a valid pointer to a `work_struct`. + if unsafe { bindings::cancel_work_sync(work_ptr) } { + // SAFETY: The work item was successfully cancelled/waited for= , and is guaranteed + // not to run again unless re-enqueued. We reclaim the ownersh= ip leaked during + // `enqueue`. + Some(unsafe { T::Pointer::reclaim(work_ptr) }) + } else { + None + } + } + /// Get a pointer to the inner `work_struct`. /// /// # Safety @@ -674,25 +864,14 @@ pub fn new( pin_init!(Self { dwork <- Opaque::ffi_init(|slot: *mut bindings::delayed_work| { // SAFETY: The `WorkItemPointer` implementation promises t= hat `run` can be used as - // the work item function. + // the work item function. We use the C-helper to ensure t= he timer function + // and data are initialized correctly according to kernel = macros. unsafe { - bindings::init_work_with_key( - core::ptr::addr_of_mut!((*slot).work), + bindings::init_delayed_work( + slot, Some(T::Pointer::run), - false, work_name.as_char_ptr(), work_key.as_ptr(), - ) - } - - // SAFETY: The `delayed_work_timer_fn` function pointer ca= n be used here because - // the timer is embedded in a `struct delayed_work`, and o= nly ever scheduled via - // the core workqueue code, and configured to run in irqsa= fe context. - unsafe { - bindings::timer_init_key( - core::ptr::addr_of_mut!((*slot).timer), - Some(bindings::delayed_work_timer_fn), - bindings::TIMER_IRQSAFE, timer_name.as_char_ptr(), timer_key.as_ptr(), ) @@ -702,6 +881,84 @@ pub fn new( }) } =20 + /// Returns whether the work item is currently pending. + /// + /// # Warning + /// + /// This method is inherently racy. See [`Work::is_pending`]. + /// + /// # Examples + /// + /// See [`Work::is_pending`]. + #[inline] + pub fn is_pending(&self) -> bool { + // SAFETY: `self.dwork` is reaching into a valid Opaque. + unsafe { + let ptr: *mut bindings::delayed_work =3D self.dwork.get(); + bindings::work_pending(core::ptr::addr_of_mut!((*ptr).work)) + } + } + + /// Cancels the delayed work item. + /// + /// If the work item was successfully cancelled (i.e., it was pending = and had not yet + /// started running), the original pointer is reclaimed and returned. + /// + /// # Guarantees + /// + /// See [`Work::cancel`]. + /// + /// # Safety + /// + /// Same as [`Work::cancel`]. + /// + /// # Examples + /// + /// See [`Work::cancel`]. + pub fn cancel(&self) -> Option + where + T: WorkItem, + { + let dwork_ptr =3D self.dwork.get(); + // SAFETY: `dwork_ptr` is a valid pointer to a `delayed_work`. + if unsafe { bindings::cancel_delayed_work(dwork_ptr) } { + // SAFETY: The work item was successfully cancelled and is gua= ranteed not to run, + // so we can safely reclaim the ownership leaked during `enque= ue`. + Some(unsafe { T::Pointer::reclaim(core::ptr::addr_of_mut!((*dw= ork_ptr).work)) }) + } else { + None + } + } + + /// Synchronously cancels the delayed work item. + /// + /// This method waits for the work item to finish if it is currently r= unning. + /// If the work item was successfully cancelled from the queue, the po= inter is + /// reclaimed and returned. + /// + /// # Guarantees + /// + /// See [`Work::cancel_sync`]. + /// + /// # Safety + /// + /// Same as [`Work::cancel_sync`]. + pub fn cancel_sync(&self) -> Option + where + T: WorkItem, + { + let dwork_ptr =3D self.dwork.get(); + // SAFETY: `dwork_ptr` is a valid pointer to a `delayed_work`. + if unsafe { bindings::cancel_delayed_work_sync(dwork_ptr) } { + // SAFETY: The work item was successfully cancelled/waited for= , and is guaranteed + // not to run again unless re-enqueued. We reclaim the ownersh= ip leaked during + // `enqueue`. + Some(unsafe { T::Pointer::reclaim(core::ptr::addr_of_mut!((*dw= ork_ptr).work)) }) + } else { + None + } + } + /// Get a pointer to the inner `delayed_work`. /// /// # Safety @@ -781,22 +1038,11 @@ unsafe fn raw_get_work( unsafe fn work_container_of( ptr: *mut $crate::workqueue::Work<$work_type $(, $id)?>, ) -> *mut Self { - // SAFETY: The caller promises that the pointer points at = a field of the right type - // in the right kind of struct. - let ptr =3D unsafe { $crate::workqueue::Work::raw_get(ptr)= }; - - // SAFETY: The caller promises that the pointer points at = a field of the right type - // in the right kind of struct. - let delayed_work =3D unsafe { - $crate::container_of!(ptr, $crate::bindings::delayed_w= ork, work) - }; - - let delayed_work: *mut $crate::workqueue::DelayedWork<$wor= k_type $(, $id)?> =3D - delayed_work.cast(); - - // SAFETY: The caller promises that the pointer points at = a field of the right type - // in the right kind of struct. - unsafe { $crate::container_of!(delayed_work, Self, $field)= } + // SAFETY: The caller promises that the pointer points at = the `work` field + // of a `delayed_work` struct, which is itself the `dwork`= field of a + // `DelayedWork` wrapper, which is the `$field` field of a= `Self` struct. + let ptr =3D ptr.cast::<$crate::workqueue::DelayedWork<$wor= k_type $(, $id)?>>(); + unsafe { $crate::container_of!(ptr, Self, $field) } } } )*}; @@ -827,6 +1073,20 @@ unsafe impl WorkItemPointer for= Arc =20 T::run(arc) } + + /// Reclaims ownership of the pointer. + /// + /// # Safety + /// + /// The pointer must have been enqueued for this work item and not yet= reclaimed. + unsafe fn reclaim(ptr: *mut bindings::work_struct) -> Self { + // The `__enqueue` method always uses a `work_struct` stored in a = `Work`. + let ptr =3D ptr.cast::>(); + // SAFETY: This computes the pointer that `__enqueue` got from `Ar= c::into_raw`. + let ptr =3D unsafe { T::work_container_of(ptr) }; + // SAFETY: This pointer comes from `Arc::into_raw` and we've been = given back ownership. + unsafe { Arc::from_raw(ptr) } + } } =20 // SAFETY: The `work_struct` raw pointer is guaranteed to be valid for the= duration of the call to @@ -874,7 +1134,8 @@ unsafe impl RawDelayedWorkItem f= or Arc { } =20 -// SAFETY: TODO. +// SAFETY: The `WorkItemPointer` implementation for `Pin>` is safe= because `KBox::from_raw` +// correctly reconstructs the box that was leaked during `enqueue` (via `K= Box::into_raw`). unsafe impl WorkItemPointer for Pin> where T: WorkItem, @@ -883,18 +1144,40 @@ unsafe impl WorkItemPointer fo= r Pin> unsafe extern "C" fn run(ptr: *mut bindings::work_struct) { // The `__enqueue` method always uses a `work_struct` stored in a = `Work`. let ptr =3D ptr.cast::>(); - // SAFETY: This computes the pointer that `__enqueue` got from `Ar= c::into_raw`. + // SAFETY: This computes the pointer that `__enqueue` got from `KB= ox::into_raw`. let ptr =3D unsafe { T::work_container_of(ptr) }; - // SAFETY: This pointer comes from `Arc::into_raw` and we've been = given back ownership. + // SAFETY: This pointer comes from `KBox::into_raw` and we've been= given back ownership. let boxed =3D unsafe { KBox::from_raw(ptr) }; // SAFETY: The box was already pinned when it was enqueued. let pinned =3D unsafe { Pin::new_unchecked(boxed) }; =20 T::run(pinned) } + + /// Reclaims ownership of the pointer. + /// + /// # Safety + /// + /// The pointer must have been enqueued for this work item and not yet= reclaimed. + unsafe fn reclaim(ptr: *mut bindings::work_struct) -> Self { + // The `__enqueue` method always uses a `work_struct` stored in a = `Work`. + let ptr =3D ptr.cast::>(); + // SAFETY: This computes the pointer that `__enqueue` got from `KB= ox::into_raw`. + let ptr =3D unsafe { T::work_container_of(ptr) }; + // SAFETY: This pointer comes from `KBox::into_raw` and we've been= given back ownership. + let boxed =3D unsafe { KBox::from_raw(ptr) }; + // SAFETY: The box was already pinned when it was enqueued. + unsafe { Pin::new_unchecked(boxed) } + } } =20 -// SAFETY: TODO. +// SAFETY: The `work_struct` raw pointer is guaranteed to be valid for the= duration of the call to +// the closure because we have exclusive ownership of the `KBox`, and we d= on't drop it ourselves. +// If `queue_work_on` returns true, it is further guaranteed to be valid u= ntil a call to the +// function pointer in `work_struct` because we leak the memory it points = to, and only reclaim it +// if the closure returns false (not reachable for KBox as it must succeed= ) or in +// `WorkItemPointer::run`, which is what the function pointer in the `work= _struct` must be +// pointing to. unsafe impl RawWorkItem for Pin> where T: WorkItem, @@ -1022,3 +1305,150 @@ pub fn system_bh_highpri() -> &'static Queue { // SAFETY: `system_bh_highpri_wq` is a C global, always available. unsafe { Queue::from_raw(bindings::system_bh_highpri_wq) } } + +/// Returns the strong count of an [`Arc`] for testing purposes. +/// +/// # Safety +/// +/// This is intended for use in KUnit tests and sample modules ONLY. +#[cfg(CONFIG_KUNIT)] +#[doc(hidden)] +pub fn arc_count(arc: &Arc) -> i32 { + // SAFETY: ArcInner has refcount as its first field. Arc points to dat= a at DATA_OFFSET. + unsafe { + let ptr =3D Arc::as_ptr(arc); + let inner_ptr =3D (ptr as *const u8).sub(Arc::::DATA_OFFSET); + let refcount_ptr =3D inner_ptr as *const i32; + core::ptr::read_volatile(refcount_ptr) + } +} + +#[macros::kunit_tests(rust_kernel_workqueue)] +mod tests { + use super::*; + use crate::sync::Arc; + + #[pin_data] + struct TestWorkItem { + #[pin] + work: Work, + value: i32, + } + + impl_has_work! { + impl HasWork for TestWorkItem { self.work } + } + + impl WorkItem for TestWorkItem { + type Pointer =3D Arc; + fn run(_this: Arc) {} + } + + #[pin_data] + struct TestDelayedWorkItem { + #[pin] + delayed_work: DelayedWork, + value: i32, + } + + impl_has_delayed_work! { + impl HasDelayedWork for TestDelayedWorkItem { self.delayed_w= ork } + } + + impl WorkItem for TestDelayedWorkItem { + type Pointer =3D Arc; + fn run(_this: Arc) {} + } + + #[test] + fn test_work_cancel_reclaim() { + let item =3D Arc::pin_init( + pin_init!(TestWorkItem { + work <- new_work!("TestWorkItem::work"), + value: 42, + }), + GFP_KERNEL, + ) + .expect("Failed to allocate TestWorkItem"); + + let initial_count =3D arc_count(&item); + + // Enqueue + let _ =3D system().enqueue(item.clone()); + + // Cancel and Reclaim (if it was pending) + if let Some(reclaimed) =3D item.work.cancel() { + assert!(arc_count(&item) =3D=3D initial_count + 1); + drop(reclaimed); + assert!(arc_count(&item) =3D=3D initial_count); + } + } + + #[test] + fn test_work_cancel_sync_reclaim() { + let item =3D Arc::pin_init( + pin_init!(TestWorkItem { + work <- new_work!("TestWorkItem::work"), + value: 42, + }), + GFP_KERNEL, + ) + .expect("Failed to allocate TestWorkItem"); + + let initial_count =3D arc_count(&item); + + // Enqueue + let _ =3D system().enqueue(item.clone()); + + // Cancel Sync and Reclaim + if let Some(reclaimed) =3D item.work.cancel_sync() { + assert!(arc_count(&item) =3D=3D initial_count + 1); + drop(reclaimed); + assert!(arc_count(&item) =3D=3D initial_count); + } + } + + #[test] + fn test_work_stress_enqueue_cancel() { + let item =3D Arc::pin_init( + pin_init!(TestWorkItem { + work <- new_work!("TestWorkItem::work"), + value: 42, + }), + GFP_KERNEL, + ) + .expect("Failed to allocate TestWorkItem"); + + for _ in 0..100 { + if let Ok(_) =3D system().enqueue(item.clone()) { + let _ =3D item.work.cancel_sync(); + } + } + + assert_eq!(arc_count(&item), 1); + } + + #[test] + fn test_delayed_work_cancel_reclaim() { + let item =3D Arc::pin_init( + pin_init!(TestDelayedWorkItem { + delayed_work <- new_delayed_work!("TestDelayedWorkItem::de= layed_work"), + value: 42, + }), + GFP_KERNEL, + ) + .expect("Failed to allocate TestDelayedWorkItem"); + + let initial_count =3D arc_count(&item); + + // Enqueue delayed (use a longer delay to ensure it stays pending) + let _ =3D system().enqueue_delayed(item.clone(), 1000); + + // Cancel and Reclaim + if let Some(reclaimed) =3D item.delayed_work.cancel() { + assert!(arc_count(&item) =3D=3D initial_count + 1); + drop(reclaimed); + assert!(arc_count(&item) =3D=3D initial_count); + } + } +} --=20 2.43.0 From nobody Sun May 24 21:37:39 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C3807361DBF; 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charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260521-workqueue-v5-sent-v7-3-fb4b4dde35ec@multicorewareinc.com> References: <20260521-workqueue-v5-sent-v7-0-fb4b4dde35ec@multicorewareinc.com> In-Reply-To: <20260521-workqueue-v5-sent-v7-0-fb4b4dde35ec@multicorewareinc.com> 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 Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Aakash Bollineni X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1779353663; l=8550; i=aakash.bollineni@multicorewareinc.com; s=20260402; h=from:subject:message-id; bh=rft5BGStO8+C5FxdozwOciq5arZiJ9dndtfJWrmdFbU=; b=d41lYReC2q0fHxByOtlQCLx6EeYv9uDpvxZ8/Si+gtCe2pr359OQSLDmjsupwcOT8N9Ozso6K t0x066NzsPyDrBrsilgyQj7q6KjINGYbXtFSQd0DjprqNeWhWoGVB/z X-Developer-Key: i=aakash.bollineni@multicorewareinc.com; a=ed25519; pk=r3Gonl+2k+8RozN9U/XwfICQdnRlAcLeeAfsExmurdE= X-Endpoint-Received: by B4 Relay for aakash.bollineni@multicorewareinc.com/20260402 with auth_id=711 X-Original-From: Aakash Bollineni Reply-To: aakash.bollineni@multicorewareinc.com From: Aakash Bollineni To ensure the safety and correctness of the improved workqueue API, this patch adds comprehensive testing infrastructure: 1. KUnit Tests: Adds an internal 'rust_kernel_workqueue' test suite to rust/kernel/workqueue.rs. These tests verify basic and synchronous cancellation, refcount stability, and concurrency safety for both standard and delayed work. 2. Sample Module: Adds samples/rust/rust_workqueue_test.rs as a standalone module that performs a 1000-iteration stress test designed to verify race-free pointer handover during concurrent enqueue/cancel operations. The tests use distinct types for standard and delayed work items to ensure clear trait dispatch and prevent field offset conflicts. Signed-off-by: Aakash Bollineni --- samples/rust/Kconfig | 11 +++ samples/rust/Makefile | 2 + samples/rust/rust_workqueue_test.rs | 191 ++++++++++++++++++++++++++++++++= ++++ 3 files changed, 204 insertions(+) diff --git a/samples/rust/Kconfig b/samples/rust/Kconfig index c49ab9106345..03288a7ffe96 100644 --- a/samples/rust/Kconfig +++ b/samples/rust/Kconfig @@ -172,6 +172,17 @@ config SAMPLE_RUST_SOC =20 If unsure, say N. =20 +config SAMPLE_RUST_WORKQUEUE + tristate "Workqueue" + depends on KUNIT + help + This option builds the Rust workqueue robust stress test sample. + + To compile this as a module, choose M here: + the module will be called rust_workqueue_test. + + If unsure, say N. + config SAMPLE_RUST_HOSTPROGS bool "Host programs" help diff --git a/samples/rust/Makefile b/samples/rust/Makefile index 6c0aaa58cccc..261aa67b6502 100644 --- a/samples/rust/Makefile +++ b/samples/rust/Makefile @@ -20,3 +20,5 @@ obj-$(CONFIG_SAMPLE_RUST_SOC) +=3D rust_soc.o rust_print-y :=3D rust_print_main.o rust_print_events.o =20 subdir-$(CONFIG_SAMPLE_RUST_HOSTPROGS) +=3D hostprogs + +obj-$(CONFIG_SAMPLE_RUST_WORKQUEUE) +=3D rust_workqueue_test.o diff --git a/samples/rust/rust_workqueue_test.rs b/samples/rust/rust_workqu= eue_test.rs new file mode 100644 index 000000000000..9b28065f23a8 --- /dev/null +++ b/samples/rust/rust_workqueue_test.rs @@ -0,0 +1,191 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Robust stress test for Rust workqueue API. + +use kernel::prelude::*; +use kernel::sync::Arc; +use kernel::time::msecs_to_jiffies; +use kernel::workqueue::{self, new_work, Work, WorkItem}; + +#[pin_data] +struct TestWorkItem { + #[pin] + work: Work, + value: i32, +} + +kernel::impl_has_work! { + impl HasWork for TestWorkItem { self.work } +} + +impl WorkItem for TestWorkItem { + type Pointer =3D Arc; + + fn run(this: Arc) { + pr_info!( + "Rust workqueue test: Work item running (value: {})\n", + this.value + ); + } +} + +#[pin_data] +struct TestDelayedWorkItem { + #[pin] + delayed_work: workqueue::DelayedWork, + value: i32, +} + +kernel::impl_has_delayed_work! { + impl HasDelayedWork for TestDelayedWorkItem { self.delayed_work } +} + +impl WorkItem for TestDelayedWorkItem { + type Pointer =3D Arc; + + fn run(this: Arc) { + pr_info!( + "Rust workqueue test: Delayed work item running (value: {})\n", + this.value + ); + } +} + +struct RustWorkqueueTest; + +impl kernel::Module for RustWorkqueueTest { + fn init(_module: &'static ThisModule) -> Result { + pr_info!("Rust workqueue test: starting robust verification (v3)\n= "); + + // 1. Basic Lifecycle with Refcount Validation (Standard Work) + { + let work_item =3D Arc::pin_init( + pin_init!(TestWorkItem { + work <- new_work!("TestWorkItem::work"), + value: 42, + }), + GFP_KERNEL, + )?; + + let initial_count =3D workqueue::arc_count(&work_item); + pr_info!("Initial Arc strong count: {}\n", initial_count); + + // Enqueue + let enqueued_item =3D work_item.clone(); + + if let Err(returned_item) =3D workqueue::system().enqueue(enqu= eued_item) { + pr_warn!("Work already pending, unexpected!\n"); + let _ =3D returned_item; + } else { + pr_info!( + "Work enqueued successfully. Strong count: {}\n", + workqueue::arc_count(&work_item) + ); + } + + // Cancel immediately + if let Some(reclaimed) =3D work_item.work.cancel() { + let count_after_cancel =3D workqueue::arc_count(&work_item= ); + pr_info!( + "Success: Work cancelled and Arc reclaimed. Strong cou= nt: {}\n", + count_after_cancel + ); + + if count_after_cancel !=3D initial_count + 1 { + pr_err!( + "ERROR: Refcount mismatch after cancel! Expected {= }, got {}\n", + initial_count + 1, + count_after_cancel + ); + return Err(ENXIO); + } + drop(reclaimed); + if workqueue::arc_count(&work_item) !=3D initial_count { + pr_err!("ERROR: Refcount mismatch after drop!\n"); + return Err(ENXIO); + } + } else { + pr_info!("Work already running or finished.\n"); + } + } + + // 2. Stress Testing: Enqueue/Cancel Sync Loop + { + pr_info!("Starting stress test (1000 iterations)...\n"); + let work_item =3D Arc::pin_init( + pin_init!(TestWorkItem { + work <- new_work!("TestWorkItem::work"), + value: 99, + }), + GFP_KERNEL, + )?; + + for i in 0..1000 { + let _ =3D workqueue::system().enqueue(work_item.clone()); + let _ =3D work_item.work.cancel_sync(); + if i % 250 =3D=3D 0 { + pr_info!("Stress test progress: {}/1000\n", i); + } + } + + if workqueue::arc_count(&work_item) !=3D 1 { + pr_err!("ERROR: Refcount leak detected after stress test!\= n"); + return Err(ENXIO); + } else { + pr_info!("Stress test completed successfully.\n"); + } + } + + // 3. Delayed Work Cancellation Test + { + let delayed_item =3D Arc::pin_init( + pin_init!(TestDelayedWorkItem { + delayed_work <- workqueue::new_delayed_work!("TestDWor= kItem::delayed_work"), + value: 7, + }), + GFP_KERNEL, + )?; + + let initial_count =3D workqueue::arc_count(&delayed_item); + + // Schedule with a long delay (5 seconds) + if let Err(returned) =3D + workqueue::system().enqueue_delayed(delayed_item.clone(), = msecs_to_jiffies(5000)) + { + drop(returned); + } else { + pr_info!( + "Delayed work enqueued. count: {}\n", + workqueue::arc_count(&delayed_item) + ); + } + + if let Some(reclaimed) =3D delayed_item.delayed_work.cancel() { + pr_info!("Success: Delayed work reclaimed. No leak.\n"); + drop(reclaimed); + } + + if workqueue::arc_count(&delayed_item) !=3D initial_count { + pr_err!("ERROR: Refcount leak after delayed cancel!\n"); + return Err(ENXIO); + } + } + + pr_info!("Rust workqueue test: all robust checks passed\n"); + Ok(RustWorkqueueTest) + } +} + +impl Drop for RustWorkqueueTest { + fn drop(&mut self) { + pr_info!("Rust workqueue test: exit\n"); + } +} + +module! { + type: RustWorkqueueTest, + name: "rust_workqueue_test", + authors: ["Aakash Bollineni"], + description: "Robust stress test for Rust workqueue API", + license: "GPL", +} --=20 2.43.0