Merge patch series "Rust support for `struct iov_iter`"

Alice Ryhl <aliceryhl@google.com> says: This series adds support for the `struct iov_iter` type. This type represents an IO buffer for reading or writing, and can be configured for either direction of communication. In Rust, we define separate types for reading and writing. This will ensure that you cannot mix them up and e.g. call copy_from_iter in a read_iter syscall. To use the new abstractions, miscdevices are given new methods read_iter and write_iter that can be used to implement the read/write syscalls on a miscdevice. The miscdevice sample is updated to provide read/write operations. Intended for Greg's miscdevice tree.

Greg Kroah-Hartman committed 1 year ago

Commit 1da0ca42 parents 2d2664f e5b0d7d6 files · +482 −3Browse files

Unified · Split

6 files

rust/kernel/fs.rs +3 −0
rust/kernel/fs/kiocb.rs +68 −0
rust/kernel/iov.rs +314 −0
rust/kernel/lib.rs +1 −0
rust/kernel/miscdevice.rs +62 −1
samples/rust/rust_misc_device.rs +34 −2

rust/kernel/fs.rs+3−0

@@ -6,3 +6,6 @@ · 5 unmodified lines
6		6
7	pub mod file;	7	pub mod file;
8	pub use self::file::{File, LocalFile};	8	pub use self::file::{File, LocalFile};
		9
		10	mod kiocb;
		11	pub use self::kiocb::Kiocb;

rust/kernel/fs/kiocb.rs+68−0

@@ -0,0 +1,68 @@
	1	// SPDX-License-Identifier: GPL-2.0
	2
	3	// Copyright (C) 2024 Google LLC.
	4
	5	//! Kernel IO callbacks.
	6	//!
	7	//! C headers: [`include/linux/fs.h`](srctree/include/linux/fs.h)
	8
	9	use core::marker::PhantomData;
	10	use core::ptr::NonNull;
	11	use kernel::types::ForeignOwnable;
	12
	13	/// Wrapper for the kernel's `struct kiocb`.
	14	///
	15	/// Currently this abstractions is incomplete and is essentially just a tuple containing a
	16	/// reference to a file and a file position.
	17	///
	18	/// The type `T` represents the filesystem or driver specific data associated with the file.
	19	///
	20	/// # Invariants
	21	///
	22	/// `inner` points at a valid `struct kiocb` whose file has the type `T` as its private data.
	23	pub struct Kiocb<'a, T> {
	24	inner: NonNull<bindings::kiocb>,
	25	_phantom: PhantomData<&'a T>,
	26	}
	27
	28	impl<'a, T: ForeignOwnable> Kiocb<'a, T> {
	29	/// Create a `Kiocb` from a raw pointer.
	30	///
	31	/// # Safety
	32	///
	33	/// The pointer must reference a valid `struct kiocb` for the duration of `'a`. The private
	34	/// data of the file must be `T`.
	35	pub unsafe fn from_raw(kiocb: *mut bindings::kiocb) -> Self {
	36	Self {
	37	// SAFETY: If a pointer is valid it is not null.
	38	inner: unsafe { NonNull::new_unchecked(kiocb) },
	39	_phantom: PhantomData,
	40	}
	41	}
	42
	43	/// Access the underlying `struct kiocb` directly.
	44	pub fn as_raw(&self) -> *mut bindings::kiocb {
	45	self.inner.as_ptr()
	46	}
	47
	48	/// Get the filesystem or driver specific data associated with the file.
	49	pub fn file(&self) -> <T as ForeignOwnable>::Borrowed<'a> {
	50	// SAFETY: We have shared access to this kiocb and hence the underlying file, so we can
	51	// read the file's private data.
	52	let private = unsafe { ((self.as_raw()).ki_filp).private_data };
	53	// SAFETY: The kiocb has shared access to the private data.
	54	unsafe { <T as ForeignOwnable>::borrow(private) }
	55	}
	56
	57	/// Gets the current value of `ki_pos`.
	58	pub fn ki_pos(&self) -> i64 {
	59	// SAFETY: We have shared access to the kiocb, so we can read its `ki_pos` field.
	60	unsafe { (*self.as_raw()).ki_pos }
	61	}
	62
	63	/// Gets a mutable reference to the `ki_pos` field.
	64	pub fn ki_pos_mut(&mut self) -> &mut i64 {
	65	// SAFETY: We have exclusive access to the kiocb, so we can write to `ki_pos`.
	66	unsafe { &mut (*self.as_raw()).ki_pos }
	67	}
	68	}

rust/kernel/iov.rs+314−0

@@ -0,0 +1,314 @@
	1	// SPDX-License-Identifier: GPL-2.0
	2
	3	// Copyright (C) 2025 Google LLC.
	4
	5	//! IO vectors.
	6	//!
	7	//! C headers: [`include/linux/iov_iter.h`](srctree/include/linux/iov_iter.h),
	8	//! [`include/linux/uio.h`](srctree/include/linux/uio.h)
	9
	10	use crate::{
	11	alloc::{Allocator, Flags},
	12	bindings,
	13	prelude::*,
	14	types::Opaque,
	15	};
	16	use core::{marker::PhantomData, mem::MaybeUninit, ptr, slice};
	17
	18	const ITER_SOURCE: bool = bindings::ITER_SOURCE != 0;
	19	const ITER_DEST: bool = bindings::ITER_DEST != 0;
	20
	21	// Compile-time assertion for the above constants.
	22	const _: () = {
	23	build_assert!(
	24	ITER_SOURCE != ITER_DEST,
	25	"ITER_DEST and ITER_SOURCE should be different."
	26	);
	27	};
	28
	29	/// An IO vector that acts as a source of data.
	30	///
	31	/// The data may come from many different sources. This includes both things in kernel-space and
	32	/// reading from userspace. It's not necessarily the case that the data source is immutable, so
	33	/// rewinding the IO vector to read the same data twice is not guaranteed to result in the same
	34	/// bytes. It's also possible that the data source is mapped in a thread-local manner using e.g.
	35	/// `kmap_local_page()`, so this type is not `Send` to ensure that the mapping is read from the
	36	/// right context in that scenario.
	37	///
	38	/// # Invariants
	39	///
	40	/// Must hold a valid `struct iov_iter` with `data_source` set to `ITER_SOURCE`. For the duration
	41	/// of `'data`, it must be safe to read from this IO vector using the standard C methods for this
	42	/// purpose.
	43	#[repr(transparent)]
	44	pub struct IovIterSource<'data> {
	45	iov: Opaque<bindings::iov_iter>,
	46	/// Represent to the type system that this value contains a pointer to readable data it does
	47	/// not own.
	48	_source: PhantomData<&'data [u8]>,
	49	}
	50
	51	impl<'data> IovIterSource<'data> {
	52	/// Obtain an `IovIterSource` from a raw pointer.
	53	///
	54	/// # Safety
	55	///
	56	/// * The referenced `struct iov_iter` must be valid and must only be accessed through the
	57	/// returned reference for the duration of `'iov`.
	58	/// * The referenced `struct iov_iter` must have `data_source` set to `ITER_SOURCE`.
	59	/// * For the duration of `'data`, it must be safe to read from this IO vector using the
	60	/// standard C methods for this purpose.
	61	#[track_caller]
	62	#[inline]
	63	pub unsafe fn from_raw<'iov>(ptr: *mut bindings::iov_iter) -> &'iov mut IovIterSource<'data> {
	64	// SAFETY: The caller ensures that `ptr` is valid.
	65	let data_source = unsafe { (*ptr).data_source };
	66	assert_eq!(data_source, ITER_SOURCE);
	67
	68	// SAFETY: The caller ensures the type invariants for the right durations, and
	69	// `IovIterSource` is layout compatible with `struct iov_iter`.
	70	unsafe { &mut *ptr.cast::<IovIterSource<'data>>() }
	71	}
	72
	73	/// Access this as a raw `struct iov_iter`.
	74	#[inline]
	75	pub fn as_raw(&mut self) -> *mut bindings::iov_iter {
	76	self.iov.get()
	77	}
	78
	79	/// Returns the number of bytes available in this IO vector.
	80	///
	81	/// Note that this may overestimate the number of bytes. For example, reading from userspace
	82	/// memory could fail with `EFAULT`, which will be treated as the end of the IO vector.
	83	#[inline]
	84	pub fn len(&self) -> usize {
	85	// SAFETY: We have shared access to this IO vector, so we can read its `count` field.
	86	unsafe {
	87	(*self.iov.get())
	88	.__bindgen_anon_1
	89	.__bindgen_anon_1
	90	.as_ref()
	91	.count
	92	}
	93	}
	94
	95	/// Returns whether there are any bytes left in this IO vector.
	96	///
	97	/// This may return `true` even if there are no more bytes available. For example, reading from
	98	/// userspace memory could fail with `EFAULT`, which will be treated as the end of the IO vector.
	99	#[inline]
	100	pub fn is_empty(&self) -> bool {
	101	self.len() == 0
	102	}
	103
	104	/// Advance this IO vector by `bytes` bytes.
	105	///
	106	/// If `bytes` is larger than the size of this IO vector, it is advanced to the end.
	107	#[inline]
	108	pub fn advance(&mut self, bytes: usize) {
	109	// SAFETY: By the type invariants, `self.iov` is a valid IO vector.
	110	unsafe { bindings::iov_iter_advance(self.as_raw(), bytes) };
	111	}
	112
	113	/// Advance this IO vector backwards by `bytes` bytes.
	114	///
	115	/// # Safety
	116	///
	117	/// The IO vector must not be reverted to before its beginning.
	118	#[inline]
	119	pub unsafe fn revert(&mut self, bytes: usize) {
	120	// SAFETY: By the type invariants, `self.iov` is a valid IO vector, and the caller
	121	// ensures that `bytes` is in bounds.
	122	unsafe { bindings::iov_iter_revert(self.as_raw(), bytes) };
	123	}
	124
	125	/// Read data from this IO vector.
	126	///
	127	/// Returns the number of bytes that have been copied.
	128	#[inline]
	129	pub fn copy_from_iter(&mut self, out: &mut [u8]) -> usize {
	130	// SAFETY: `Self::copy_from_iter_raw` guarantees that it will not write any uninitialized
	131	// bytes in the provided buffer, so `out` is still a valid `u8` slice after this call.
	132	let out = unsafe { &mut (ptr::from_mut(out) as mut [MaybeUninit<u8>]) };
	133
	134	self.copy_from_iter_raw(out).len()
	135	}
	136
	137	/// Read data from this IO vector and append it to a vector.
	138	///
	139	/// Returns the number of bytes that have been copied.
	140	#[inline]
	141	pub fn copy_from_iter_vec<A: Allocator>(
	142	&mut self,
	143	out: &mut Vec<u8, A>,
	144	flags: Flags,
	145	) -> Result<usize> {
	146	out.reserve(self.len(), flags)?;
	147	let len = self.copy_from_iter_raw(out.spare_capacity_mut()).len();
	148	// SAFETY:
	149	// - `len` is the length of a subslice of the spare capacity, so `len` is at most the
	150	// length of the spare capacity.
	151	// - `Self::copy_from_iter_raw` guarantees that the first `len` bytes of the spare capacity
	152	// have been initialized.
	153	unsafe { out.inc_len(len) };
	154	Ok(len)
	155	}
	156
	157	/// Read data from this IO vector into potentially uninitialized memory.
	158	///
	159	/// Returns the sub-slice of the output that has been initialized. If the returned slice is
	160	/// shorter than the input buffer, then the entire IO vector has been read.
	161	///
	162	/// This will never write uninitialized bytes to the provided buffer.
	163	#[inline]
	164	pub fn copy_from_iter_raw(&mut self, out: &mut [MaybeUninit<u8>]) -> &mut [u8] {
	165	let capacity = out.len();
	166	let out = out.as_mut_ptr().cast::<u8>();
	167
	168	// GUARANTEES: The C API guarantees that it does not write uninitialized bytes to the
	169	// provided buffer.
	170	// SAFETY:
	171	// * By the type invariants, it is still valid to read from this IO vector.
	172	// * `out` is valid for writing for `capacity` bytes because it comes from a slice of
	173	// that length.
	174	let len = unsafe { bindings::_copy_from_iter(out.cast(), capacity, self.as_raw()) };
	175
	176	// SAFETY: The underlying C api guarantees that initialized bytes have been written to the
	177	// first `len` bytes of the spare capacity.
	178	unsafe { slice::from_raw_parts_mut(out, len) }
	179	}
	180	}
	181
	182	/// An IO vector that acts as a destination for data.
	183	///
	184	/// IO vectors support many different types of destinations. This includes both buffers in
	185	/// kernel-space and writing to userspace. It's possible that the destination buffer is mapped in a
	186	/// thread-local manner using e.g. `kmap_local_page()`, so this type is not `Send` to ensure that
	187	/// the mapping is written to the right context in that scenario.
	188	///
	189	/// # Invariants
	190	///
	191	/// Must hold a valid `struct iov_iter` with `data_source` set to `ITER_DEST`. For the duration of
	192	/// `'data`, it must be safe to write to this IO vector using the standard C methods for this
	193	/// purpose.
	194	#[repr(transparent)]
	195	pub struct IovIterDest<'data> {
	196	iov: Opaque<bindings::iov_iter>,
	197	/// Represent to the type system that this value contains a pointer to writable data it does
	198	/// not own.
	199	_source: PhantomData<&'data mut [u8]>,
	200	}
	201
	202	impl<'data> IovIterDest<'data> {
	203	/// Obtain an `IovIterDest` from a raw pointer.
	204	///
	205	/// # Safety
	206	///
	207	/// * The referenced `struct iov_iter` must be valid and must only be accessed through the
	208	/// returned reference for the duration of `'iov`.
	209	/// * The referenced `struct iov_iter` must have `data_source` set to `ITER_DEST`.
	210	/// * For the duration of `'data`, it must be safe to write to this IO vector using the
	211	/// standard C methods for this purpose.
	212	#[track_caller]
	213	#[inline]
	214	pub unsafe fn from_raw<'iov>(ptr: *mut bindings::iov_iter) -> &'iov mut IovIterDest<'data> {
	215	// SAFETY: The caller ensures that `ptr` is valid.
	216	let data_source = unsafe { (*ptr).data_source };
	217	assert_eq!(data_source, ITER_DEST);
	218
	219	// SAFETY: The caller ensures the type invariants for the right durations, and
	220	// `IovIterSource` is layout compatible with `struct iov_iter`.
	221	unsafe { &mut *ptr.cast::<IovIterDest<'data>>() }
	222	}
	223
	224	/// Access this as a raw `struct iov_iter`.
	225	#[inline]
	226	pub fn as_raw(&mut self) -> *mut bindings::iov_iter {
	227	self.iov.get()
	228	}
	229
	230	/// Returns the number of bytes available in this IO vector.
	231	///
	232	/// Note that this may overestimate the number of bytes. For example, reading from userspace
	233	/// memory could fail with EFAULT, which will be treated as the end of the IO vector.
	234	#[inline]
	235	pub fn len(&self) -> usize {
	236	// SAFETY: We have shared access to this IO vector, so we can read its `count` field.
	237	unsafe {
	238	(*self.iov.get())
	239	.__bindgen_anon_1
	240	.__bindgen_anon_1
	241	.as_ref()
	242	.count
	243	}
	244	}
	245
	246	/// Returns whether there are any bytes left in this IO vector.
	247	///
	248	/// This may return `true` even if there are no more bytes available. For example, reading from
	249	/// userspace memory could fail with EFAULT, which will be treated as the end of the IO vector.
	250	#[inline]
	251	pub fn is_empty(&self) -> bool {
	252	self.len() == 0
	253	}
	254
	255	/// Advance this IO vector by `bytes` bytes.
	256	///
	257	/// If `bytes` is larger than the size of this IO vector, it is advanced to the end.
	258	#[inline]
	259	pub fn advance(&mut self, bytes: usize) {
	260	// SAFETY: By the type invariants, `self.iov` is a valid IO vector.
	261	unsafe { bindings::iov_iter_advance(self.as_raw(), bytes) };
	262	}
	263
	264	/// Advance this IO vector backwards by `bytes` bytes.
	265	///
	266	/// # Safety
	267	///
	268	/// The IO vector must not be reverted to before its beginning.
	269	#[inline]
	270	pub unsafe fn revert(&mut self, bytes: usize) {
	271	// SAFETY: By the type invariants, `self.iov` is a valid IO vector, and the caller
	272	// ensures that `bytes` is in bounds.
	273	unsafe { bindings::iov_iter_revert(self.as_raw(), bytes) };
	274	}
	275
	276	/// Write data to this IO vector.
	277	///
	278	/// Returns the number of bytes that were written. If this is shorter than the provided slice,
	279	/// then no more bytes can be written.
	280	#[inline]
	281	pub fn copy_to_iter(&mut self, input: &[u8]) -> usize {
	282	// SAFETY:
	283	// * By the type invariants, it is still valid to write to this IO vector.
	284	// * `input` is valid for `input.len()` bytes.
	285	unsafe { bindings::_copy_to_iter(input.as_ptr().cast(), input.len(), self.as_raw()) }
	286	}
	287
	288	/// Utility for implementing `read_iter` given the full contents of the file.
	289	///
	290	/// The full contents of the file being read from is represented by `contents`. This call will
	291	/// write the appropriate sub-slice of `contents` and update the file position in `ppos` so
	292	/// that the file will appear to contain `contents` even if takes multiple reads to read the
	293	/// entire file.
	294	#[inline]
	295	pub fn simple_read_from_buffer(&mut self, ppos: &mut i64, contents: &[u8]) -> Result<usize> {
	296	if *ppos < 0 {
	297	return Err(EINVAL);
	298	}
	299	let Ok(pos) = usize::try_from(*ppos) else {
	300	return Ok(0);
	301	};
	302	if pos >= contents.len() {
	303	return Ok(0);
	304	}
	305
	306	// BOUNDS: We just checked that `pos < contents.len()` above.
	307	let num_written = self.copy_to_iter(&contents[pos..]);
	308
	309	// OVERFLOW: `pos+num_written <= contents.len() <= isize::MAX <= i64::MAX`.
	310	*ppos = (pos + num_written) as i64;
	311
	312	Ok(num_written)
	313	}
	314	}

rust/kernel/lib.rs+1−0

@@ -92,6 +92,7 @@ pub mod fs; · 91 unmodified lines
92	pub mod init;	92	pub mod init;
93	pub mod io;	93	pub mod io;
94	pub mod ioctl;	94	pub mod ioctl;
		95	pub mod iov;
95	pub mod jump_label;	96	pub mod jump_label;
96	#[cfg(CONFIG_KUNIT)]	97	#[cfg(CONFIG_KUNIT)]
97	pub mod kunit;	98	pub mod kunit;

rust/kernel/miscdevice.rs+62−1

@@ -13,7 +13,8 @@ use crate::{ · 12 unmodified lines
13	device::Device,	13	device::Device,
14	error::{to_result, Error, Result, VTABLE_DEFAULT_ERROR},	14	error::{to_result, Error, Result, VTABLE_DEFAULT_ERROR},
15	ffi::{c_int, c_long, c_uint, c_ulong},	15	ffi::{c_int, c_long, c_uint, c_ulong},
16	fs::File,	16	fs::{File, Kiocb},
		17	iov::{IovIterDest, IovIterSource},
17	mm::virt::VmaNew,	18	mm::virt::VmaNew,
18	prelude::*,	19	prelude::*,
19	seq_file::SeqFile,	20	seq_file::SeqFile,
@@ -141,6 +142,16 @@ pub trait MiscDevice: Sized { · 121 unmodified lines
141	build_error!(VTABLE_DEFAULT_ERROR)	142	build_error!(VTABLE_DEFAULT_ERROR)
142	}	143	}
143		144
		145	/// Read from this miscdevice.
		146	fn read_iter(_kiocb: Kiocb<'_, Self::Ptr>, _iov: &mut IovIterDest<'_>) -> Result<usize> {
		147	build_error!(VTABLE_DEFAULT_ERROR)
		148	}
		149
		150	/// Write to this miscdevice.
		151	fn write_iter(_kiocb: Kiocb<'_, Self::Ptr>, _iov: &mut IovIterSource<'_>) -> Result<usize> {
		152	build_error!(VTABLE_DEFAULT_ERROR)
		153	}
		154
144	/// Handler for ioctls.	155	/// Handler for ioctls.
145	///	156	///
146	/// The `cmd` argument is usually manipulated using the utilities in [`kernel::ioctl`].	157	/// The `cmd` argument is usually manipulated using the utilities in [`kernel::ioctl`].
@@ -245,6 +256,46 @@ impl<T: MiscDevice> MiscdeviceVTable<T> { · 98 unmodified lines
245	0	256	0
246	}	257	}
247		258
		259	/// # Safety
		260	///
		261	/// `kiocb` must be correspond to a valid file that is associated with a
		262	/// `MiscDeviceRegistration<T>`. `iter` must be a valid `struct iov_iter` for writing.
		263	unsafe extern "C" fn read_iter(
		264	kiocb: *mut bindings::kiocb,
		265	iter: *mut bindings::iov_iter,
		266	) -> isize {
		267	// SAFETY: The caller provides a valid `struct kiocb` associated with a
		268	// `MiscDeviceRegistration<T>` file.
		269	let kiocb = unsafe { Kiocb::from_raw(kiocb) };
		270	// SAFETY: This is a valid `struct iov_iter` for writing.
		271	let iov = unsafe { IovIterDest::from_raw(iter) };
		272
		273	match T::read_iter(kiocb, iov) {
		274	Ok(res) => res as isize,
		275	Err(err) => err.to_errno() as isize,
		276	}
		277	}
		278
		279	/// # Safety
		280	///
		281	/// `kiocb` must be correspond to a valid file that is associated with a
		282	/// `MiscDeviceRegistration<T>`. `iter` must be a valid `struct iov_iter` for writing.
		283	unsafe extern "C" fn write_iter(
		284	kiocb: *mut bindings::kiocb,
		285	iter: *mut bindings::iov_iter,
		286	) -> isize {
		287	// SAFETY: The caller provides a valid `struct kiocb` associated with a
		288	// `MiscDeviceRegistration<T>` file.
		289	let kiocb = unsafe { Kiocb::from_raw(kiocb) };
		290	// SAFETY: This is a valid `struct iov_iter` for reading.
		291	let iov = unsafe { IovIterSource::from_raw(iter) };
		292
		293	match T::write_iter(kiocb, iov) {
		294	Ok(res) => res as isize,
		295	Err(err) => err.to_errno() as isize,
		296	}
		297	}
		298
248	/// # Safety	299	/// # Safety
249	///	300	///
250	/// `file` must be a valid file that is associated with a `MiscDeviceRegistration<T>`.	301	/// `file` must be a valid file that is associated with a `MiscDeviceRegistration<T>`.
@@ -341,6 +392,16 @@ impl<T: MiscDevice> MiscdeviceVTable<T> { · 90 unmodified lines
341	open: Some(Self::open),	392	open: Some(Self::open),
342	release: Some(Self::release),	393	release: Some(Self::release),
343	mmap: if T::HAS_MMAP { Some(Self::mmap) } else { None },	394	mmap: if T::HAS_MMAP { Some(Self::mmap) } else { None },
		395	read_iter: if T::HAS_READ_ITER {
		396	Some(Self::read_iter)
		397	} else {
		398	None
		399	},
		400	write_iter: if T::HAS_WRITE_ITER {
		401	Some(Self::write_iter)
		402	} else {
		403	None
		404	},
344	unlocked_ioctl: if T::HAS_IOCTL {	405	unlocked_ioctl: if T::HAS_IOCTL {
345	Some(Self::ioctl)	406	Some(Self::ioctl)
346	} else {	407	} else {

samples/rust/rust_misc_device.rs+34−2

@@ -100,8 +100,9 @@ use core::pin::Pin; · 99 unmodified lines
100	use kernel::{	100	use kernel::{
101	c_str,	101	c_str,
102	device::Device,	102	device::Device,
103	fs::File,	103	fs::{File, Kiocb},
104	ioctl::{_IO, _IOC_SIZE, _IOR, _IOW},	104	ioctl::{_IO, _IOC_SIZE, _IOR, _IOW},
		105	iov::{IovIterDest, IovIterSource},
105	miscdevice::{MiscDevice, MiscDeviceOptions, MiscDeviceRegistration},	106	miscdevice::{MiscDevice, MiscDeviceOptions, MiscDeviceRegistration},
106	new_mutex,	107	new_mutex,
107	prelude::*,	108	prelude::*,
@@ -143,6 +144,7 @@ impl kernel::InPlaceModule for RustMiscDeviceModule { · 35 unmodified lines
143		144
144	struct Inner {	145	struct Inner {
145	value: i32,	146	value: i32,
		147	buffer: KVVec<u8>,
146	}	148	}
147		149
148	#[pin_data(PinnedDrop)]	150	#[pin_data(PinnedDrop)]
@@ -164,7 +166,10 @@ impl MiscDevice for RustMiscDevice { · 15 unmodified lines
164	KBox::try_pin_init(	166	KBox::try_pin_init(
165	try_pin_init! {	167	try_pin_init! {
166	RustMiscDevice {	168	RustMiscDevice {
167	inner <- new_mutex!( Inner{ value: 0_i32 } ),	169	inner <- new_mutex!(Inner {
		170	value: 0_i32,
		171	buffer: KVVec::new(),
		172	}),
168	dev: dev,	173	dev: dev,
169	}	174	}
170	},	175	},
@@ -172,6 +177,33 @@ impl MiscDevice for RustMiscDevice { · 1 unmodified line
172	)	177	)
173	}	178	}
174		179
		180	fn read_iter(mut kiocb: Kiocb<'_, Self::Ptr>, iov: &mut IovIterDest<'_>) -> Result<usize> {
		181	let me = kiocb.file();
		182	dev_info!(me.dev, "Reading from Rust Misc Device Sample\n");
		183
		184	let inner = me.inner.lock();
		185	// Read the buffer contents, taking the file position into account.
		186	let read = iov.simple_read_from_buffer(kiocb.ki_pos_mut(), &inner.buffer)?;
		187
		188	Ok(read)
		189	}
		190
		191	fn write_iter(mut kiocb: Kiocb<'_, Self::Ptr>, iov: &mut IovIterSource<'_>) -> Result<usize> {
		192	let me = kiocb.file();
		193	dev_info!(me.dev, "Writing to Rust Misc Device Sample\n");
		194
		195	let mut inner = me.inner.lock();
		196
		197	// Replace buffer contents.
		198	inner.buffer.clear();
		199	let len = iov.copy_from_iter_vec(&mut inner.buffer, GFP_KERNEL)?;
		200
		201	// Set position to zero so that future `read` calls will see the new contents.
		202	*kiocb.ki_pos_mut() = 0;
		203
		204	Ok(len)
		205	}
		206
175	fn ioctl(me: Pin<&RustMiscDevice>, _file: &File, cmd: u32, arg: usize) -> Result<isize> {	207	fn ioctl(me: Pin<&RustMiscDevice>, _file: &File, cmd: u32, arg: usize) -> Result<isize> {
176	dev_info!(me.dev, "IOCTLing Rust Misc Device Sample\n");	208	dev_info!(me.dev, "IOCTLing Rust Misc Device Sample\n");
177		209

Merge patch series "Rust support for `struct iov_iter`"

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