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66 lines
2.1 KiB
66 lines
2.1 KiB
// Copyright 2020 The Pigweed Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not
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// use this file except in compliance with the License. You may obtain a copy of
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// the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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// License for the specific language governing permissions and limitations under
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// the License.
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#include "pw_sync/interrupt_spin_lock.h"
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#include "pw_assert/assert.h"
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#include "pw_interrupt/context.h"
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#include "task.h"
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namespace pw::sync {
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void InterruptSpinLock::lock() {
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if (interrupt::InInterruptContext()) {
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native_type_.saved_interrupt_mask = taskENTER_CRITICAL_FROM_ISR();
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} else { // Task context
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taskENTER_CRITICAL();
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}
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// We can't deadlock here so crash instead.
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PW_CHECK(!native_type_.locked.load(std::memory_order_relaxed),
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"Recursive InterruptSpinLock::lock() detected");
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native_type_.locked.store(true, std::memory_order_relaxed);
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}
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bool InterruptSpinLock::try_lock() {
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if (interrupt::InInterruptContext()) {
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UBaseType_t saved_interrupt_mask = taskENTER_CRITICAL_FROM_ISR();
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if (native_type_.locked.load(std::memory_order_relaxed)) {
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// Already locked, restore interrupts and bail out.
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taskEXIT_CRITICAL_FROM_ISR(saved_interrupt_mask);
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return false;
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}
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native_type_.saved_interrupt_mask = saved_interrupt_mask;
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} else { // Task context
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taskENTER_CRITICAL();
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if (native_type_.locked.load(std::memory_order_relaxed)) {
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// ALready locked, restore interrupts and bail out.
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taskEXIT_CRITICAL();
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return false;
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}
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}
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native_type_.locked.store(true, std::memory_order_relaxed);
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return true;
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}
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void InterruptSpinLock::unlock() {
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native_type_.locked.store(false, std::memory_order_relaxed);
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if (interrupt::InInterruptContext()) {
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taskEXIT_CRITICAL_FROM_ISR(native_type_.saved_interrupt_mask);
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} else { // Task context
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taskEXIT_CRITICAL();
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}
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}
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} // namespace pw::sync
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