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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2024 Google LLC.
//! Version of `MmWithUser` using `mmput_async`.//!//! This is a separate file from `mm.rs` due to the dependency on `CONFIG_MMU=y`.#![cfg(CONFIG_MMU)]
use crate::{ bindings, mm::MmWithUser, sync::aref::{ARef, AlwaysRefCounted},};use core::{ops::Deref, ptr::NonNull};
/// A wrapper for the kernel's `struct mm_struct`.////// This type is identical to `MmWithUser` except that it uses `mmput_async` when dropping a/// refcount. This means that the destructor of `ARef<MmWithUserAsync>` is safe to call in atomic/// context.////// # Invariants////// Values of this type are always refcounted using `mmget`. The value of `mm_users` is non-zero.#[repr(transparent)]pub struct MmWithUserAsync { mm: MmWithUser,}
// SAFETY: It is safe to call `mmput_async` on another thread than where `mmget` was called.unsafe impl Send for MmWithUserAsync {}// SAFETY: All methods on `MmWithUserAsync` can be called in parallel from several threads.unsafe impl Sync for MmWithUserAsync {}
// SAFETY: By the type invariants, this type is always refcounted.unsafe impl AlwaysRefCounted for MmWithUserAsync { #[inline] fn inc_ref(&self) { // SAFETY: The pointer is valid since self is a reference. unsafe { bindings::mmget(self.as_raw()) }; }
#[inline] unsafe fn dec_ref(obj: NonNull<Self>) { // SAFETY: The caller is giving up their refcount. unsafe { bindings::mmput_async(obj.cast().as_ptr()) }; }}
// Make all `MmWithUser` methods available on `MmWithUserAsync`.impl Deref for MmWithUserAsync { type Target = MmWithUser;
#[inline] fn deref(&self) -> &MmWithUser { &self.mm }}
impl MmWithUser { /// Use `mmput_async` when dropping this refcount. #[inline] pub fn into_mmput_async(me: ARef<MmWithUser>) -> ARef<MmWithUserAsync> { // SAFETY: The layouts and invariants are compatible. unsafe { ARef::from_raw(ARef::into_raw(me).cast()) } }}