@@ -12,6 +12,7 @@
#include "build_assert.c"
#include "build_bug.c"
#include "err.c"
+#include "kernel.c"
#include "kunit.c"
#include "mutex.c"
#include "page.c"
new file mode 100644
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/kernel.h>
+
+void rust_helper_cpu_relax(void)
+{
+ cpu_relax();
+}
+
+void rust_helper___might_sleep(const char *file, int line)
+{
+ __might_sleep(file, line);
+}
@@ -58,6 +58,7 @@ macro_rules! declare_err {
declare_err!(EPIPE, "Broken pipe.");
declare_err!(EDOM, "Math argument out of domain of func.");
declare_err!(ERANGE, "Math result not representable.");
+ declare_err!(ETIMEDOUT, "Connection timed out.");
declare_err!(ERESTARTSYS, "Restart the system call.");
declare_err!(ERESTARTNOINTR, "System call was interrupted by a signal and will be restarted.");
declare_err!(ERESTARTNOHAND, "Restart if no handler.");
new file mode 100644
@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Input and Output.
+
+pub mod poll;
new file mode 100644
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! IO polling.
+//!
+//! C header: [`include/linux/iopoll.h`](srctree/include/linux/iopoll.h).
+
+use crate::{
+ error::{code::*, Result},
+ processor::cpu_relax,
+ time::{delay::fsleep, Delta, Instant},
+};
+
+/// Polls periodically until a condition is met or a timeout is reached.
+///
+/// Public but hidden since it should only be used from public macros.
+#[doc(hidden)]
+pub fn read_poll_timeout<Op, Cond, T: Copy>(
+ mut op: Op,
+ cond: Cond,
+ sleep_delta: Delta,
+ timeout_delta: Delta,
+) -> Result<T>
+where
+ Op: FnMut() -> Result<T>,
+ Cond: Fn(T) -> bool,
+{
+ let start = Instant::now();
+ let sleep = !sleep_delta.is_zero();
+ let timeout = !timeout_delta.is_zero();
+
+ let val = loop {
+ let val = op()?;
+ if cond(val) {
+ // Unlike the C version, we immediately return.
+ // We know a condition is met so we don't need to check again.
+ return Ok(val);
+ }
+ if timeout && start.elapsed() > timeout_delta {
+ // Should we return Err(ETIMEDOUT) here instead of call op() again
+ // without a sleep between? But we follow the C version. op() could
+ // take some time so might be worth checking again.
+ break op()?;
+ }
+ if sleep {
+ fsleep(sleep_delta);
+ }
+ // fsleep() could be busy-wait loop so we always call cpu_relax().
+ cpu_relax();
+ };
+
+ if cond(val) {
+ Ok(val)
+ } else {
+ Err(ETIMEDOUT)
+ }
+}
+
+/// Print debug information if it's called inside atomic sections.
+///
+/// Equivalent to the kernel's [`__might_sleep`].
+#[macro_export]
+macro_rules! __might_sleep {
+ () => {
+ #[cfg(CONFIG_DEBUG_ATOMIC_SLEEP)]
+ // SAFETY: FFI call.
+ unsafe {
+ $crate::bindings::__might_sleep(
+ c_str!(::core::file!()).as_char_ptr(),
+ ::core::line!() as i32,
+ )
+ }
+ };
+}
+
+/// Polls periodically until a condition is met or a timeout is reached.
+///
+/// `op` is called repeatedly until `cond` returns `true` or the timeout is
+/// reached. The return value of `op` is passed to `cond`.
+///
+/// `sleep_delta` is the duration to sleep between calls to `op`.
+/// If `sleep_delta` is less than one microsecond, the function will busy-wait.
+///
+/// `timeout_delta` is the maximum time to wait for `cond` to return `true`.
+///
+/// This macro can only be used in a nonatomic context.
+#[macro_export]
+macro_rules! readx_poll_timeout {
+ ($op:expr, $cond:expr, $sleep_delta:expr, $timeout_delta:expr) => {{
+ if !$sleep_delta.is_zero() {
+ $crate::__might_sleep!();
+ }
+
+ $crate::io::poll::read_poll_timeout($op, $cond, $sleep_delta, $timeout_delta)
+ }};
+}
@@ -35,6 +35,7 @@
#[cfg(CONFIG_RUST_FW_LOADER_ABSTRACTIONS)]
pub mod firmware;
pub mod init;
+pub mod io;
pub mod ioctl;
#[cfg(CONFIG_KUNIT)]
pub mod kunit;
@@ -44,6 +45,7 @@
pub mod page;
pub mod prelude;
pub mod print;
+pub mod processor;
pub mod sizes;
pub mod rbtree;
mod static_assert;
new file mode 100644
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Processor related primitives.
+//!
+//! C header: [`include/linux/processor.h`](srctree/include/linux/processor.h).
+
+/// Lower CPU power consumption or yield to a hyperthreaded twin processor.
+///
+/// It also happens to serve as a compiler barrier.
+pub fn cpu_relax() {
+ // SAFETY: FFI call.
+ unsafe { bindings::cpu_relax() }
+}
Add read_poll_timeout functions which poll periodically until a condition is met or a timeout is reached. C's read_poll_timeout (include/linux/iopoll.h) is a complicated macro and a simple wrapper for Rust doesn't work. So this implements the same functionality in Rust. The C version uses usleep_range() while the Rust version uses fsleep(), which uses the best sleep method so it works with spans that usleep_range() doesn't work nicely with. Unlike the C version, __might_sleep() is used instead of might_sleep() to show proper debug info; the file name and line number. might_resched() could be added to match what the C version does but this function works without it. The sleep_before_read argument isn't supported since there is no user for now. It's rarely used in the C version. For the proper debug info, readx_poll_timeout() and __might_sleep() are implemented as a macro. We could implement them as a normal function if there is a clean way to get a null-terminated string without allocation from core::panic::Location::file(). readx_poll_timeout() can only be used in a nonatomic context. This requirement is not checked by these abstractions, but it is intended that klint [1] or a similar tool will be used to check it in the future. Link: https://rust-for-linux.com/klint [1] Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com> --- rust/helpers/helpers.c | 1 + rust/helpers/kernel.c | 13 ++++++ rust/kernel/error.rs | 1 + rust/kernel/io.rs | 5 +++ rust/kernel/io/poll.rs | 95 ++++++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 2 + rust/kernel/processor.rs | 13 ++++++ 7 files changed, 130 insertions(+) create mode 100644 rust/helpers/kernel.c create mode 100644 rust/kernel/io.rs create mode 100644 rust/kernel/io/poll.rs create mode 100644 rust/kernel/processor.rs