/*
* Copyright (c) 2007 Jan Hudecek
* Copyright (c) 2006 Jakub Jermar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup genericddi
* @{
*/
/** @file tasklet.c
* @brief Tasklet implementation
*/
#include <arch.h>
#include <config.h>
#include <arch/types.h>
#include <arch/asm.h>
#include <proc/tasklet.h>
#include <synch/spinlock.h>
#include <time/delay.h>
#include <proc/thread.h>
#include <panic.h>
#include <print.h>
#include <synch/waitq.h>
#include <cpu.h>
#include <proc/scheduler.h>
/** Timeout length in the tasklet thread */
#define TASKLET_THREAD_SLEEPDELAY 10000
///** Priority of the tasklet thread */
#define TASKLET_THREAD_PRIORITY 1
/** Tasklet state enum */
typedef enum {
TASKLET_STATE_NOTACTIVE = 0,
TASKLET_STATE_SCHEDULED = 1,
TASKLET_STATE_RUNNING = 2,
TASKLET_STATE_DISABLED = 4
} tasklet_state_enum;
/** Spinlock protecting list of tasklets */
SPINLOCK_INITIALIZE(tasklet_lock);
/** array of tasklet lists for every CPU */
tasklet_descriptor_t** tasklet_list;
/** Initializes tasklets - except for the tasklet thread */
void tasklet_init(void)
{
int i;
tasklet_list
=malloc(sizeof(tasklet_descriptor_t
*)*config.
cpu_count,0); if (tasklet_list==0)
panic_printf("tasklet list mem not allocated\n");
for(i=0;i<config.cpu_count;i++) {
tasklet_list[i]=0;
}
spinlock_initialize(&tasklet_lock, "tasklet_lock");
}
/**
* Creates and runs the tasklet thread
*
* @param kernel_task Pointer to the kernel task - for create_thread
*/
void tasklet_run_tasklet_thread(task_t * kernel_task)
{
//create the tasklet_thread, it's wired to the current cpu, we'll migrate it ourselves
thread_t* t= thread_create(&tasklet_thread, NULL, kernel_task, THREAD_FLAG_WIRED, "tasklet_thread", false);
if (t==NULL) {
panic_printf("tasklet thread not created\n");
} else {
spinlock_lock(&t->lock);
//we'll default on the first CPU
t->cpu = &cpus[0];
t->priority = TASKLET_THREAD_PRIORITY;
spinlock_unlock(&t->lock);
thread_ready(t);
}
}
/** Thread which keeps executing scheduled enabled tasklets
* @param data not used
*/
void tasklet_thread(void* data)
{
#ifdef CONFIG_SMP
int current_cpu, new_cpu ;
cpu_t *cpu;
#endif
waitq_t wq;
waitq_initialize(&wq);
//the infinite loop
while (true) {
//execute any scheduled tasklets
tasklet_do();
#ifdef CONFIG_SMP
//check whether other CPUs have tasklets to execute
if (config.cpu_active>1) {
current_cpu = CPU->id;
//find the first cpu with nonempty tasklet_list
for (new_cpu = (current_cpu + 1) % config.cpu_count; new_cpu!=current_cpu && tasklet_list[new_cpu]==0 ;
new_cpu=(new_cpu + 1)% config.cpu_count);
//if we found a CPU with unsatisfied tasklet schedule to run there. It must be active!
if (new_cpu!=current_cpu && cpus[new_cpu].active) {
//we need to migrate this thread to CPU with id new_cpu
cpu = &cpus[new_cpu];
spinlock_lock(&THREAD->lock);
//move tasklet_thread on the new_cpu
THREAD->cpu = cpu;
spinlock_unlock(&THREAD->lock);
}
}
#endif
waitq_sleep_timeout(&wq, (uint32_t)TASKLET_THREAD_SLEEPDELAY, 0);
}
}
/** Initializes tasklet structure
* @param func tasklet callback function to be called
* @param data pointer to be passed to the tasklet function
*/
tasklet_descriptor_t* tasklet_register(void (*func)(void* data), void* data)
{
tasklet_descriptor_t
* tasklet
=malloc(sizeof(tasklet_descriptor_t
),0); tasklet->data = data;
tasklet->func = func;
tasklet->state = TASKLET_STATE_NOTACTIVE;
tasklet->next = 0;
return tasklet;
}
/** Schedules the tasklet for execution on current CPU
* @param t tasklet to be scheduled
*/
void tasklet_schedule(tasklet_descriptor_t* t)
{
tasklet_schedule_SMP(t, CPU->id);
}
/** Schedules the tasklet for execution on id CPU
* @param t tasklet to be scheduled
* @param id CPU id on which the tasklet will be scheduled
*/
void tasklet_schedule_SMP(tasklet_descriptor_t* t, uint32_t id)
{
spinlock_lock(&tasklet_lock);
//clear notactive, running and scheduled flags
t->state &= TASKLET_STATE_DISABLED;
//set the scheduled flag
t->state |= TASKLET_STATE_SCHEDULED;
t->next=tasklet_list[id];
tasklet_list[id]=t;
spinlock_unlock(&tasklet_lock);
}
/** Tasklet will not be run, even if scheduled
* @param t tasklet to be disabled
*/
void tasklet_disable(tasklet_descriptor_t* t)
{
spinlock_lock(&tasklet_lock);
//set the disabled flag
t->state |= TASKLET_STATE_DISABLED;
spinlock_unlock(&tasklet_lock);
}
/** Tasklet will be run if scheduled
* @param t tasklet to be enabled
*/
void tasklet_enable(tasklet_descriptor_t* t)
{
spinlock_lock(&tasklet_lock);
//clear the disabled flag
t->state &= ~TASKLET_STATE_DISABLED;
spinlock_unlock(&tasklet_lock);
}
/** Executes scheduled enabled tasklets on current CPU
* this function could be called from other parts of kernel */
void tasklet_do(void)
{
spinlock_lock(&tasklet_lock);
tasklet_descriptor_t* t = tasklet_list[CPU->id];
if (t) {
//empty the tasklet_list
tasklet_list[CPU->id]=0;
spinlock_unlock(&tasklet_lock);
do {
if (!(t->state & TASKLET_STATE_DISABLED)) {
if (t->func) {
t->state = TASKLET_STATE_RUNNING;
t->func(t->data);
//clear running flag, set not active
t->state &= ~TASKLET_STATE_RUNNING;
t->state |= TASKLET_STATE_NOTACTIVE;
} else
panic_printf("tasklet func NULL\n");
} else {
//return it back to the queue of scheduled tasklets
spinlock_lock(&tasklet_lock);
t->next = tasklet_list[CPU->id];
tasklet_list[CPU->id] = t;
spinlock_unlock(&tasklet_lock);
}
t=t->next;
}
while (t);
}
else
spinlock_unlock(&tasklet_lock);
}
/** Frees the tasklet structure when no longer needed. The function doesn't provide
* any synchronization, the caller must be sure, that the tasklet is not scheduled.
*
* @param tasklet to be freed
*/
void tasklet_free(tasklet_descriptor_t* t)
{
spinlock_lock(&tasklet_lock);
if (t->state == TASKLET_STATE_NOTACTIVE)
else
panic_printf("attempting to free an active tasklet");
spinlock_unlock(&tasklet_lock);
}