kernel/sync/spinlock_core.rs

// Copyright 2025 The Pigweed Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
#![no_std]

pub trait BareSpinLockApi {
    type Guard<'a>
    where
        Self: 'a;

    // Rust does not support const function in traits.  However it should be
    // considered that the BareSpinlockApi includes:
    //
    // `const fn new() -> Self`

    fn try_lock(&self) -> Option<Self::Guard<'_>>;

    fn lock(&self) -> Self::Guard<'_> {
        loop {
            if let Some(sentinel) = self.try_lock() {
                return sentinel;
            }
        }
    }

    // TODO - konkers: Add optimized path for functions that know they are in
    // atomic context (i.e. interrupt handlers).
}