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[2620:137:e000::1:20]) by mx.google.com with ESMTP id sc37-20020a1709078a2500b00947d54e4c1fsi1610575ejc.88.2023.04.05.10.54.13; Wed, 05 Apr 2023 10:54:37 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=H3b5JZrX; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232116AbjDERxA (ORCPT + 99 others); Wed, 5 Apr 2023 13:53:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40474 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233100AbjDERw4 (ORCPT ); Wed, 5 Apr 2023 13:52:56 -0400 Received: from mail-oi1-x22e.google.com (mail-oi1-x22e.google.com [IPv6:2607:f8b0:4864:20::22e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 10FB37A9E; Wed, 5 Apr 2023 10:52:24 -0700 (PDT) Received: by mail-oi1-x22e.google.com with SMTP id y184so27232400oiy.8; Wed, 05 Apr 2023 10:52:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1680717143; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=Uocgwe3402X+SGxBrEAOB8aX32adol5RFJ3Rm7rkR1M=; b=H3b5JZrXjwVVxh77g6AfD4FgP2iz9QMuIN26A643ILL/PT2nI2gwzcwQ3aRhdCWr5h oMJdzkZ1ycexjNw/7i70b3yc7mqOAPNNWFVh4tNUyPb7o/SxmN4F7htwm3QHQnF8OhSM uoXh2V9/hpmkRz1aa28P+CDh9vDNRof/ZsLHCh/4amlnOlr1O7EtOUSK2PbTzraTBd1V F6QH83tfMRTdQ5To7gYPt0LKZq3XZC1Ty98eoZP9KfbxM3t94rbgOG9SV3W39n3dFHQx jK8ZUBaj8UZO/WCePVLvesyjnDWHSxB3jnWb7elRwj9r+HHCs8AWjS+pIAe1dWCQEgNI MGOw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680717143; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Uocgwe3402X+SGxBrEAOB8aX32adol5RFJ3Rm7rkR1M=; b=CfgFrD51/Hy+JNeEujlM+eeRnmOlj4VOw91m49F0pzhgoewT5cnLs2dxS96cO9YvWo 4cuAU6SvvoDY5/M5+zn0gIrDEeU5I+IMNuFqND3+fr8ZVmA7gojb9NJwLyHejOQpOVly +ZJRIChPD3opKjU6RCLKpB8jBzVaqF64LlXbTy6P8kUxfDK9SZ7Y5E0GiINJs7H+Cw6Z MPbbURDDg0a4RZeB+7WHSlmVwhZOtG9LOtb2ogMnzNC8FGINuA1RDqHum4nkUFAqRMR5 xxeHIVU9fbxw4Cend+Od+8ywdTnI1dyG30kJnKUtpH8uDFVAo+2eAfepPySj+ffezHaH CZ2A== X-Gm-Message-State: AAQBX9dE9QOzuw7M3P8V4HSBYuAssMAv/oTrvauoB5HYMSjTq2ul32p+ uQiicFRcu8OODxvkK1CujTVPXXJ2d4Ftgw== X-Received: by 2002:a05:6808:b39:b0:38b:6b17:f72a with SMTP id t25-20020a0568080b3900b0038b6b17f72amr892617oij.3.1680717141396; Wed, 05 Apr 2023 10:52:21 -0700 (PDT) Received: from wedsonaf-dev.home.lan ([189.124.190.154]) by smtp.googlemail.com with ESMTPSA id w185-20020aca62c2000000b003896e31867esm6604045oib.49.2023.04.05.10.52.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Apr 2023 10:52:21 -0700 (PDT) From: Wedson Almeida Filho To: rust-for-linux@vger.kernel.org Cc: Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?B?= =?utf-8?q?j=C3=B6rn_Roy_Baron?= , linux-kernel@vger.kernel.org, Wedson Almeida Filho , Ingo Molnar , Peter Zijlstra Subject: [PATCH v2 09/13] rust: add basic `Task` Date: Wed, 5 Apr 2023 14:51:07 -0300 Message-Id: <20230405175111.5974-9-wedsonaf@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230405175111.5974-1-wedsonaf@gmail.com> References: <20230405175111.5974-1-wedsonaf@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-0.2 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1762359800351986970?= X-GMAIL-MSGID: =?utf-8?q?1762359800351986970?= From: Wedson Almeida Filho It is an abstraction for C's `struct task_struct`. It implements `AlwaysRefCounted`, so the refcount of the wrapped object is managed safely on the Rust side. Cc: Ingo Molnar Cc: Peter Zijlstra Signed-off-by: Wedson Almeida Filho --- v1 -> v2: No changes rust/bindings/bindings_helper.h | 1 + rust/helpers.c | 19 +++++++++ rust/kernel/lib.rs | 1 + rust/kernel/task.rs | 71 +++++++++++++++++++++++++++++++++ 4 files changed, 92 insertions(+) create mode 100644 rust/kernel/task.rs diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index 75d85bd6c592..03656a44a83f 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -8,6 +8,7 @@ #include #include +#include /* `bindgen` gets confused at certain things. */ const gfp_t BINDINGS_GFP_KERNEL = GFP_KERNEL; diff --git a/rust/helpers.c b/rust/helpers.c index e42f5b446f92..58a194042c86 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -23,6 +23,7 @@ #include #include #include +#include __noreturn void rust_helper_BUG(void) { @@ -75,6 +76,12 @@ void rust_helper_spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags) } EXPORT_SYMBOL_GPL(rust_helper_spin_unlock_irqrestore); +int rust_helper_signal_pending(struct task_struct *t) +{ + return signal_pending(t); +} +EXPORT_SYMBOL_GPL(rust_helper_signal_pending); + refcount_t rust_helper_REFCOUNT_INIT(int n) { return (refcount_t)REFCOUNT_INIT(n); @@ -93,6 +100,18 @@ bool rust_helper_refcount_dec_and_test(refcount_t *r) } EXPORT_SYMBOL_GPL(rust_helper_refcount_dec_and_test); +void rust_helper_get_task_struct(struct task_struct *t) +{ + get_task_struct(t); +} +EXPORT_SYMBOL_GPL(rust_helper_get_task_struct); + +void rust_helper_put_task_struct(struct task_struct *t) +{ + put_task_struct(t); +} +EXPORT_SYMBOL_GPL(rust_helper_put_task_struct); + /* * We use `bindgen`'s `--size_t-is-usize` option to bind the C `size_t` type * as the Rust `usize` type, so we can use it in contexts where Rust diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index d9df77132fa2..4e1d5ba2e241 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -43,6 +43,7 @@ mod static_assert; pub mod std_vendor; pub mod str; pub mod sync; +pub mod task; pub mod types; #[doc(hidden)] diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs new file mode 100644 index 000000000000..8d7a8222990f --- /dev/null +++ b/rust/kernel/task.rs @@ -0,0 +1,71 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Tasks (threads and processes). +//! +//! C header: [`include/linux/sched.h`](../../../../include/linux/sched.h). + +use crate::bindings; +use core::{cell::UnsafeCell, ptr}; + +/// Wraps the kernel's `struct task_struct`. +/// +/// # Invariants +/// +/// Instances of this type are always ref-counted, that is, a call to `get_task_struct` ensures +/// that the allocation remains valid at least until the matching call to `put_task_struct`. +#[repr(transparent)] +pub struct Task(pub(crate) UnsafeCell); + +// SAFETY: It's OK to access `Task` through references from other threads because we're either +// accessing properties that don't change (e.g., `pid`, `group_leader`) or that are properly +// synchronised by C code (e.g., `signal_pending`). +unsafe impl Sync for Task {} + +/// The type of process identifiers (PIDs). +type Pid = bindings::pid_t; + +impl Task { + /// Returns the group leader of the given task. + pub fn group_leader(&self) -> &Task { + // SAFETY: By the type invariant, we know that `self.0` is valid. + let ptr = unsafe { *ptr::addr_of!((*self.0.get()).group_leader) }; + + // SAFETY: The lifetime of the returned task reference is tied to the lifetime of `self`, + // and given that a task has a reference to its group leader, we know it must be valid for + // the lifetime of the returned task reference. + unsafe { &*ptr.cast() } + } + + /// Returns the PID of the given task. + pub fn pid(&self) -> Pid { + // SAFETY: By the type invariant, we know that `self.0` is valid. + unsafe { *ptr::addr_of!((*self.0.get()).pid) } + } + + /// Determines whether the given task has pending signals. + pub fn signal_pending(&self) -> bool { + // SAFETY: By the type invariant, we know that `self.0` is valid. + unsafe { bindings::signal_pending(self.0.get()) != 0 } + } + + /// Wakes up the task. + pub fn wake_up(&self) { + // SAFETY: By the type invariant, we know that `self.0.get()` is non-null and valid. + // And `wake_up_process` is safe to be called for any valid task, even if the task is + // running. + unsafe { bindings::wake_up_process(self.0.get()) }; + } +} + +// SAFETY: The type invariants guarantee that `Task` is always ref-counted. +unsafe impl crate::types::AlwaysRefCounted for Task { + fn inc_ref(&self) { + // SAFETY: The existence of a shared reference means that the refcount is nonzero. + unsafe { bindings::get_task_struct(self.0.get()) }; + } + + unsafe fn dec_ref(obj: ptr::NonNull) { + // SAFETY: The safety requirements guarantee that the refcount is nonzero. + unsafe { bindings::put_task_struct(obj.cast().as_ptr()) } + } +}