@@ -6,7 +6,11 @@
//! variable.
use super::{lock::Backend, lock::Guard, LockClassKey};
-use crate::{bindings, init::PinInit, pin_init, str::CStr, types::Opaque};
+use crate::{
+ bindings, init::PinInit, pin_init, str::CStr, task::MAX_SCHEDULE_TIMEOUT, time::Jiffies,
+ types::Opaque,
+};
+use core::ffi::c_long;
use core::marker::PhantomPinned;
use macros::pin_data;
@@ -102,7 +106,12 @@ pub fn new(name: &'static CStr, key: &'static LockClassKey) -> impl PinInit<Self
})
}
- fn wait_internal<T: ?Sized, B: Backend>(&self, wait_state: u32, guard: &mut Guard<'_, T, B>) {
+ fn wait_internal<T: ?Sized, B: Backend>(
+ &self,
+ wait_state: u32,
+ guard: &mut Guard<'_, T, B>,
+ timeout_in_jiffies: c_long,
+ ) -> c_long {
let wait = Opaque::<bindings::wait_queue_entry>::uninit();
// SAFETY: `wait` points to valid memory.
@@ -113,11 +122,13 @@ fn wait_internal<T: ?Sized, B: Backend>(&self, wait_state: u32, guard: &mut Guar
bindings::prepare_to_wait_exclusive(self.wait_list.get(), wait.get(), wait_state as _)
};
- // SAFETY: No arguments, switches to another thread.
- guard.do_unlocked(|| unsafe { bindings::schedule() });
+ // SAFETY: Switches to another thread. The timeout can be any number.
+ let ret = guard.do_unlocked(|| unsafe { bindings::schedule_timeout(timeout_in_jiffies) });
// SAFETY: Both `wait` and `wait_list` point to valid memory.
unsafe { bindings::finish_wait(self.wait_list.get(), wait.get()) };
+
+ ret
}
/// Releases the lock and waits for a notification in uninterruptible mode.
@@ -127,7 +138,7 @@ fn wait_internal<T: ?Sized, B: Backend>(&self, wait_state: u32, guard: &mut Guar
/// [`CondVar::notify_one`] or [`CondVar::notify_all`]. Note that it may also wake up
/// spuriously.
pub fn wait<T: ?Sized, B: Backend>(&self, guard: &mut Guard<'_, T, B>) {
- self.wait_internal(bindings::TASK_UNINTERRUPTIBLE, guard);
+ self.wait_internal(bindings::TASK_UNINTERRUPTIBLE, guard, MAX_SCHEDULE_TIMEOUT);
}
/// Releases the lock and waits for a notification in interruptible mode.
@@ -138,10 +149,31 @@ pub fn wait<T: ?Sized, B: Backend>(&self, guard: &mut Guard<'_, T, B>) {
/// Returns whether there is a signal pending.
#[must_use = "wait_interruptible returns if a signal is pending, so the caller must check the return value"]
pub fn wait_interruptible<T: ?Sized, B: Backend>(&self, guard: &mut Guard<'_, T, B>) -> bool {
- self.wait_internal(bindings::TASK_INTERRUPTIBLE, guard);
+ self.wait_internal(bindings::TASK_INTERRUPTIBLE, guard, MAX_SCHEDULE_TIMEOUT);
crate::current!().signal_pending()
}
+ /// Releases the lock and waits for a notification in interruptible mode.
+ ///
+ /// Atomically releases the given lock (whose ownership is proven by the guard) and puts the
+ /// thread to sleep. It wakes up when notified by [`CondVar::notify_one`] or
+ /// [`CondVar::notify_all`], or when a timeout occurs, or when the thread receives a signal.
+ #[must_use = "wait_interruptible_timeout returns if a signal is pending, so the caller must check the return value"]
+ pub fn wait_interruptible_timeout<T: ?Sized, B: Backend>(
+ &self,
+ guard: &mut Guard<'_, T, B>,
+ jiffies: Jiffies,
+ ) -> CondVarTimeoutResult {
+ let jiffies = jiffies.try_into().unwrap_or(MAX_SCHEDULE_TIMEOUT);
+ let res = self.wait_internal(bindings::TASK_INTERRUPTIBLE, guard, jiffies);
+
+ match (res as Jiffies, crate::current!().signal_pending()) {
+ (jiffies, true) => CondVarTimeoutResult::Signal { jiffies },
+ (0, false) => CondVarTimeoutResult::Timeout,
+ (jiffies, false) => CondVarTimeoutResult::Woken { jiffies },
+ }
+ }
+
/// Calls the kernel function to notify the appropriate number of threads with the given flags.
fn notify(&self, count: i32, flags: u32) {
// SAFETY: `wait_list` points to valid memory.
@@ -181,3 +213,19 @@ pub fn notify_all(&self) {
self.notify(0, 0);
}
}
+
+/// The return type of `wait_timeout`.
+pub enum CondVarTimeoutResult {
+ /// The timeout was reached.
+ Timeout,
+ /// Somebody woke us up.
+ Woken {
+ /// Remaining sleep duration.
+ jiffies: Jiffies,
+ },
+ /// A signal occurred.
+ Signal {
+ /// Remaining sleep duration.
+ jiffies: Jiffies,
+ },
+}
@@ -139,7 +139,7 @@ pub struct Guard<'a, T: ?Sized, B: Backend> {
unsafe impl<T: Sync + ?Sized, B: Backend> Sync for Guard<'_, T, B> {}
impl<T: ?Sized, B: Backend> Guard<'_, T, B> {
- pub(crate) fn do_unlocked(&mut self, cb: impl FnOnce()) {
+ pub(crate) fn do_unlocked<U>(&mut self, cb: impl FnOnce() -> U) -> U {
// SAFETY: The caller owns the lock, so it is safe to unlock it.
unsafe { B::unlock(self.lock.state.get(), &self.state) };
@@ -147,7 +147,7 @@ pub(crate) fn do_unlocked(&mut self, cb: impl FnOnce()) {
let _relock =
ScopeGuard::new(|| unsafe { B::relock(self.lock.state.get(), &mut self.state) });
- cb();
+ cb()
}
}
@@ -5,7 +5,10 @@
//! C header: [`include/linux/sched.h`](srctree/include/linux/sched.h).
use crate::{bindings, types::Opaque};
-use core::{marker::PhantomData, ops::Deref, ptr};
+use core::{ffi::c_long, marker::PhantomData, ops::Deref, ptr};
+
+/// A sentinal value used for infinite timeouts.
+pub const MAX_SCHEDULE_TIMEOUT: c_long = c_long::MAX;
/// Returns the currently running task.
#[macro_export]