os_kernel_lock.c — 内核锁机制

源文件路径: kernel/source/os_kernel_lock.c

引用章节: 4.2.8 调度器锁定

核心机制

内核锁（Kernel Lock）是 OneOS 保护内核临界区的核心机制：

• SMP 模式：使用架构自旋锁 + 中断禁用，防止多核同时进入内核
• 单核模式：使用递归计数 + 断言检测，防止错误的嵌套进入/退出

完整源码

/**
 ***********************************************************************************************************************
 * Copyright (c) 2020, China Mobile Communications Group Co.,Ltd.
 *
 * 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
 *
 *     http://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.
 *
 * @file        os_kernel_lock.c
 *
 * @brief       This file implements the operations of kernel lock.
 *
 * @revision
 * Date         Author          Notes
 * 2020-10-13   OneOS Team      First Version
 ***********************************************************************************************************************
 */

#include <oneos_config.h>
#include <os_types.h>
#include <os_stddef.h>
#include <os_assert.h>
#include <os_errno.h>
#include <os_spinlock.h>
#include <arch_interrupt.h>
#include "os_kernel_internal.h"

#ifdef OS_USING_SMP

struct kernel_lock
{
#ifdef OS_USING_KERNEL_LOCK_CHECK
    int32_t cpu_index; /*cpu + 1*/
#endif
    arch_spinlock_t lock;
};

static struct kernel_lock gs_os_kernel_lock = {
#ifdef OS_USING_KERNEL_LOCK_CHECK
    .cpu_index = 0,
#endif
    .lock = ARCH_SPINLOCK_INIT_VALUE(SPINLOCK_ARCH_UNLOCKED),
};

/**
 * @brief 进入内核临界区（SMP 版本）
 *        先关中断，再获取自旋锁
 * @return 中断保存状态
 */
os_ubase_t k_kernel_enter(void)
{
#ifdef OS_USING_KERNEL_LOCK_CHECK
    int32_t current_cpu_index;
#endif
    register os_ubase_t irq_save;

    irq_save = os_irq_lock();

#ifdef OS_USING_KERNEL_LOCK_CHECK
    current_cpu_index = os_cpu_id_get();
    OS_ASSERT_EX(gs_os_kernel_lock.cpu_index != (current_cpu_index + 1),
                 "Kernel lock owner nest");
#endif
    arch_spin_lock(&gs_os_kernel_lock.lock);

#ifdef OS_USING_KERNEL_LOCK_CHECK
    gs_os_kernel_lock.cpu_index = current_cpu_index + 1;
#endif
    return irq_save;
}

/**
 * @brief 退出内核临界区（SMP 版本）
 *        先释放自旋锁，再恢复中断
 */
void k_kernel_exit(os_ubase_t irq_save)
{
#ifdef OS_USING_KERNEL_LOCK_CHECK
    OS_ASSERT_EX(gs_os_kernel_lock.cpu_index == (os_cpu_id_get() + 1),
                 "Kernel lock owner nest");
    gs_os_kernel_lock.cpu_index = 0;
#endif
    arch_spin_unlock(&gs_os_kernel_lock.lock);
    os_irq_unlock(irq_save);
}

/* k_kernel_spin_lock / k_kernel_spin_unlock: 不关中断的版本 */
void k_kernel_spin_lock(void)
{
#ifdef OS_USING_KERNEL_LOCK_CHECK
    int32_t current_cpu_index = os_cpu_id_get();
    OS_ASSERT_EX(gs_os_kernel_lock.cpu_index != (current_cpu_index + 1),
                 "Kernel lock owner nest");
#endif
    arch_spin_lock(&gs_os_kernel_lock.lock);
#ifdef OS_USING_KERNEL_LOCK_CHECK
    gs_os_kernel_lock.cpu_index = current_cpu_index + 1;
#endif
}

void k_kernel_spin_unlock(void)
{
#ifdef OS_USING_KERNEL_LOCK_CHECK
    int32_t current_cpu_index = os_cpu_id_get();
    OS_ASSERT_EX(gs_os_kernel_lock.cpu_index == (current_cpu_index + 1),
                 "Kernel lock owner nest");
    gs_os_kernel_lock.cpu_index = 0;
#endif
    arch_spin_unlock(&gs_os_kernel_lock.lock);
}

#else /* !OS_USING_SMP -- 单核模式 */

int32_t g_os_kernel_lock_cnt = 0;

/**
 * @brief 进入内核临界区检测（单核版本）
 *        使用递归计数防止错误嵌套
 */
void k_kernel_enter_check(void)
{
#ifdef OS_USING_KERNEL_LOCK_CHECK
    os_bool_t fault_active = os_is_fault_active();
    if (OS_NULL != g_os_current_task)
    {
        if (OS_TRUE == fault_active)
        {
            /* 异常上下文：不做检测 */
        }
        else
        {
            OS_ASSERT_EX(0 == g_os_kernel_lock_cnt,
                         "Kernel enter check failed, task(%s), irq(%u), ref_cnt(%d)",
                         g_os_current_task->name,
                         os_irq_num(),
                         g_os_kernel_lock_cnt);
            g_os_kernel_lock_cnt++;
        }
    }
#endif
}

/**
 * @brief 退出内核临界区检测（单核版本）
 */
void k_kernel_exit_check(void)
{
#ifdef OS_USING_KERNEL_LOCK_CHECK
    os_bool_t fault_active = os_is_fault_active();
    if (OS_NULL != g_os_current_task)
    {
        if (OS_TRUE == fault_active)
        {
            /* 异常上下文：不做检测 */
        }
        else
        {
            OS_ASSERT_EX(1 == g_os_kernel_lock_cnt,
                         "Kernel exit check failed, task(%s), irq(%u), ref_cnt(%d)",
                         g_os_current_task->name,
                         os_irq_num(),
                         g_os_kernel_lock_cnt);
            g_os_kernel_lock_cnt--;
        }
    }
#endif
}
#endif /* OS_USING_SMP */

关键函数说明

函数	模式	行为
k_kernel_enter	SMP	关中断 → 获取自旋锁 → 返回 IRQ 状态
k_kernel_exit	SMP	释放自旋锁 → 恢复中断
k_kernel_enter_check	单核	断言递归计数=0，然后+1
k_kernel_exit_check	单核	断言递归计数=1，然后-1