
- the function join_kernel_task delivers the return value of the task, which is watinting for -spinlocks supports irq save functions git-svn-id: http://svn.lfbs.rwth-aachen.de/svn/scc/trunk/MetalSVM@21 315a16e6-25f9-4109-90ae-ca3045a26c18
244 lines
5.6 KiB
C
244 lines
5.6 KiB
C
/*
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* Copyright 2010 Stefan Lankes, Chair for Operating Systems,
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* RWTH Aachen University
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://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,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* This file is part of MetalSVM.
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*/
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#include <metalsvm/stdio.h>
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#include <metalsvm/stdlib.h>
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#include <metalsvm/string.h>
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#include <metalsvm/mmu.h>
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#include <metalsvm/tasks.h>
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#include <metalsvm/processor.h>
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#include <metalsvm/spinlocks.h>
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task_t* current_task = NULL;
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static task_t task_table[MAX_TASKS];
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static spinlock_t table_lock = SPINLOCK_INIT;
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int multitasking_init(void) {
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memset(task_table, 0, sizeof(task_t)*MAX_TASKS);
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task_table[0].id = 0;
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task_table[0].mm.usage = 0;
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task_table[0].stack = NULL;
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task_table[0].stack_size = 8192;
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task_table[0].status = TASK_RUNNING;
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task_table[0].idle = 0;
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current_task = task_table;
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return 0;
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}
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static void wakeup_blocked_tasks(void* result)
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{
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unsigned int i;
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spinlock_lock_irqsave(&table_lock);
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/* wake up blocked tasks */
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for(i=0; i<MAX_TASKS; i++) {
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if (current_task->blocked_tasks[i] && (task_table[i].status == TASK_BLOCKED)) {
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task_table[i].return_value = result;
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task_table[i].status = TASK_READY;
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}
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current_task->blocked_tasks[i] = 0;
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}
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spinlock_unlock_irqsave(&table_lock);
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}
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void NORETURN leave_task(void) {
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void* result = NULL;
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get_return_value(result);
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kprintf("Terminate task: %u, return value = %p\n", current_task->id, result);
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wakeup_blocked_tasks(result);
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current_task->status = TASK_FINISHED;
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schedule();
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kputs("Kernel panic: scheduler found no valid task\n");
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while(1) {
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NOP8;
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}
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}
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void NORETURN abort(void) {
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void* result = (void*) -1;
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kprintf("Abort task: %u\n", current_task->id);
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wakeup_blocked_tasks(result);
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current_task->status = TASK_FINISHED;
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schedule();
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kputs("Kernel panic: scheduler found no valid task\n");
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while(1) {
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NOP8;
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}
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}
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int create_kernel_task(tid_t* id, entry_point_t ep, void* arg, size_t stack_size)
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{
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int ret = -1;
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unsigned int i;
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if (BUILTIN_EXPECT(!ep, 0))
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return -1;
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if (!stack_size)
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stack_size = DEFAULT_STACK_SIZE;
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spinlock_lock_irqsave(&table_lock);
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for(i=0; i<MAX_TASKS; i++) {
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if (task_table[i].status == TASK_INVALID) {
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if (task_table[i].stack)
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kfree(task_table[i].stack, task_table[i].stack_size);
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if (task_table[i].mm.usage) {
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kprintf("Task %d has a memory leax (%d byte)\n", task_table[i].id, task_table[i].mm.usage);
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task_table[i].mm.usage = 0;
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}
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task_table[i].stack = create_stack(task_table+i, stack_size);
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if (!task_table[i].stack)
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break;
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task_table[i].stack_size = stack_size;
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task_table[i].top = task_table[i].stack + stack_size - sizeof(size_t);
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task_table[i].ip = 0;
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task_table[i].id = i;
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memset(task_table[i].blocked_tasks, 0x00, sizeof(unsigned char)*MAX_TASKS);
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task_table[i].return_value = NULL;
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task_table[i].status = TASK_READY;
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task_table[i].idle = 0;
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if (id)
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*id = i;
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ret = create_default_frame(task_table+i, ep, arg);
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break;
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}
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}
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spinlock_unlock_irqsave(&table_lock);
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return ret;
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}
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int join_kernel_task(tid_t id, void** result)
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{
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spinlock_lock_irqsave(&table_lock);
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/*
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* idle tasks are not allowed to wait for another task
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* they should always run...
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*/
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if (BUILTIN_EXPECT(current_task->idle, 0))
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goto join_out;
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/* a task is not able to wait for itself */
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if (BUILTIN_EXPECT(current_task->id == id, 0))
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goto join_out;
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/* invalid id */
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if (BUILTIN_EXPECT(id >= MAX_TASKS, 0))
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goto join_out;
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/* task already finished */
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if (BUILTIN_EXPECT(task_table[id].status == TASK_INVALID, 0))
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goto join_out;
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/* task already finished */
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if (BUILTIN_EXPECT(task_table[id].status == TASK_FINISHED, 0))
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goto join_out;
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task_table[id].blocked_tasks[current_task->id] = 1;
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current_task->status = TASK_BLOCKED;
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spinlock_unlock_irqsave(&table_lock);
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schedule();
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if (result) {
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*result = current_task->return_value;
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current_task->return_value = NULL;
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}
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return 0;
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join_out:
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spinlock_unlock_irqsave(&table_lock);
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return -1;
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}
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int wakeup_task(tid_t id)
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{
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int ret = -1;
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spinlock_lock_irqsave(&table_lock);
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if (task_table[id].status != TASK_BLOCKED) {
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kprintf("Task %u is already unblocked\n", id);
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goto wakeup_out;
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}
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task_table[id].status = TASK_READY;
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ret = 0;
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wakeup_out:
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spinlock_unlock_irqsave(&table_lock);
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return ret;
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}
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task_t* get_new_task(void)
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{
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task_t* ret;
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unsigned int i, new_id;
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spinlock_lock(&table_lock);
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/* signalize that this task could be reuse */
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if (current_task->status == TASK_FINISHED)
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current_task->status = TASK_INVALID;
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for(i=1; i <= MAX_TASKS; i++) {
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new_id = (current_task->id + i) % MAX_TASKS;
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if (!task_table[new_id].idle && task_table[new_id].status == TASK_READY) {
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if (current_task->status == TASK_RUNNING)
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current_task->status = TASK_READY;
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task_table[new_id].status = TASK_RUNNING;
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ret = task_table+new_id;
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goto get_task_out;
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}
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}
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if (!(current_task->idle) && (current_task->status == TASK_RUNNING)) {
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ret = current_task;
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goto get_task_out;
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}
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/*
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* we switch to the idle task (id=0), if the current task terminates
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* and no other is ready
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*/
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task_table[0].status = TASK_RUNNING;
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ret = task_table+0;
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get_task_out:
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spinlock_unlock(&table_lock);
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return ret;
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}
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