diff options
Diffstat (limited to 'rust/kernel')
| -rw-r--r-- | rust/kernel/fs/file.rs | 10 | ||||
| -rw-r--r-- | rust/kernel/mm.rs | 56 | ||||
| -rw-r--r-- | rust/kernel/mm/mmput_async.rs | 68 |
3 files changed, 78 insertions, 56 deletions
diff --git a/rust/kernel/fs/file.rs b/rust/kernel/fs/file.rs index 13a0e44cd1aa..72d84fb0e266 100644 --- a/rust/kernel/fs/file.rs +++ b/rust/kernel/fs/file.rs @@ -219,12 +219,13 @@ unsafe impl AlwaysRefCounted for File { /// must be on the same thread as this file. /// /// [`assume_no_fdget_pos`]: LocalFile::assume_no_fdget_pos +#[repr(transparent)] pub struct LocalFile { inner: Opaque<bindings::file>, } // SAFETY: The type invariants guarantee that `LocalFile` is always ref-counted. This implementation -// makes `ARef<File>` own a normal refcount. +// makes `ARef<LocalFile>` own a normal refcount. unsafe impl AlwaysRefCounted for LocalFile { #[inline] fn inc_ref(&self) { @@ -235,7 +236,8 @@ unsafe impl AlwaysRefCounted for LocalFile { #[inline] unsafe fn dec_ref(obj: ptr::NonNull<LocalFile>) { // SAFETY: To call this method, the caller passes us ownership of a normal refcount, so we - // may drop it. The cast is okay since `File` has the same representation as `struct file`. + // may drop it. The cast is okay since `LocalFile` has the same representation as + // `struct file`. unsafe { bindings::fput(obj.cast().as_ptr()) } } } @@ -273,7 +275,7 @@ impl LocalFile { #[inline] pub unsafe fn from_raw_file<'a>(ptr: *const bindings::file) -> &'a LocalFile { // SAFETY: The caller guarantees that the pointer is not dangling and stays valid for the - // duration of 'a. The cast is okay because `File` is `repr(transparent)`. + // duration of `'a`. The cast is okay because `LocalFile` is `repr(transparent)`. // // INVARIANT: The caller guarantees that there are no problematic `fdget_pos` calls. unsafe { &*ptr.cast() } @@ -347,7 +349,7 @@ impl File { #[inline] pub unsafe fn from_raw_file<'a>(ptr: *const bindings::file) -> &'a File { // SAFETY: The caller guarantees that the pointer is not dangling and stays valid for the - // duration of 'a. The cast is okay because `File` is `repr(transparent)`. + // duration of `'a`. The cast is okay because `File` is `repr(transparent)`. // // INVARIANT: The caller guarantees that there are no problematic `fdget_pos` calls. unsafe { &*ptr.cast() } diff --git a/rust/kernel/mm.rs b/rust/kernel/mm.rs index 615907a0f3b4..43f525c0d16c 100644 --- a/rust/kernel/mm.rs +++ b/rust/kernel/mm.rs @@ -10,7 +10,6 @@ //! control what happens when userspace reads or writes to that region of memory. //! //! C header: [`include/linux/mm.h`](srctree/include/linux/mm.h) -#![cfg(CONFIG_MMU)] use crate::{ bindings, @@ -21,6 +20,10 @@ use core::{ops::Deref, ptr::NonNull}; pub mod virt; use virt::VmaRef; +#[cfg(CONFIG_MMU)] +pub use mmput_async::MmWithUserAsync; +mod mmput_async; + /// A wrapper for the kernel's `struct mm_struct`. /// /// This represents the address space of a userspace process, so each process has one `Mm` @@ -111,50 +114,6 @@ impl Deref for MmWithUser { } } -/// 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 - } -} - // These methods are safe to call even if `mm_users` is zero. impl Mm { /// Returns a raw pointer to the inner `mm_struct`. @@ -206,13 +165,6 @@ impl MmWithUser { unsafe { &*ptr.cast() } } - /// 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()) } - } - /// Attempt to access a vma using the vma read lock. /// /// This is an optimistic trylock operation, so it may fail if there is contention. In that diff --git a/rust/kernel/mm/mmput_async.rs b/rust/kernel/mm/mmput_async.rs new file mode 100644 index 000000000000..9289e05f7a67 --- /dev/null +++ b/rust/kernel/mm/mmput_async.rs @@ -0,0 +1,68 @@ +// 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, + types::{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()) } + } +} |