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// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
/*
* Copyright (c) 2016 Mellanox Technologies Ltd. All rights reserved.
* Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.
*/
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/hardirq.h>
#include "rxe.h"
int __rxe_do_task(struct rxe_task *task)
{
int ret;
while ((ret = task->func(task->arg)) == 0)
;
task->ret = ret;
return ret;
}
/*
* this locking is due to a potential race where
* a second caller finds the task already running
* but looks just after the last call to func
*/
void rxe_do_task(struct tasklet_struct *t)
{
int cont;
int ret;
struct rxe_task *task = from_tasklet(task, t, tasklet);
unsigned int iterations = RXE_MAX_ITERATIONS;
spin_lock_bh(&task->state_lock);
switch (task->state) {
case TASK_STATE_START:
task->state = TASK_STATE_BUSY;
spin_unlock_bh(&task->state_lock);
break;
case TASK_STATE_BUSY:
task->state = TASK_STATE_ARMED;
fallthrough;
case TASK_STATE_ARMED:
spin_unlock_bh(&task->state_lock);
return;
default:
spin_unlock_bh(&task->state_lock);
pr_warn("%s failed with bad state %d\n", __func__, task->state);
return;
}
do {
cont = 0;
ret = task->func(task->arg);
spin_lock_bh(&task->state_lock);
switch (task->state) {
case TASK_STATE_BUSY:
if (ret) {
task->state = TASK_STATE_START;
} else if (iterations--) {
cont = 1;
} else {
/* reschedule the tasklet and exit
* the loop to give up the cpu
*/
tasklet_schedule(&task->tasklet);
task->state = TASK_STATE_START;
}
break;
/* someone tried to run the task since the last time we called
* func, so we will call one more time regardless of the
* return value
*/
case TASK_STATE_ARMED:
task->state = TASK_STATE_BUSY;
cont = 1;
break;
default:
pr_warn("%s failed with bad state %d\n", __func__,
task->state);
}
spin_unlock_bh(&task->state_lock);
} while (cont);
task->ret = ret;
}
int rxe_init_task(struct rxe_task *task, void *arg, int (*func)(void *))
{
task->arg = arg;
task->func = func;
task->destroyed = false;
tasklet_setup(&task->tasklet, rxe_do_task);
task->state = TASK_STATE_START;
spin_lock_init(&task->state_lock);
return 0;
}
void rxe_cleanup_task(struct rxe_task *task)
{
bool idle;
/*
* Mark the task, then wait for it to finish. It might be
* running in a non-tasklet (direct call) context.
*/
task->destroyed = true;
do {
spin_lock_bh(&task->state_lock);
idle = (task->state == TASK_STATE_START);
spin_unlock_bh(&task->state_lock);
} while (!idle);
tasklet_kill(&task->tasklet);
}
void rxe_run_task(struct rxe_task *task)
{
if (task->destroyed)
return;
rxe_do_task(&task->tasklet);
}
void rxe_sched_task(struct rxe_task *task)
{
if (task->destroyed)
return;
tasklet_schedule(&task->tasklet);
}
void rxe_disable_task(struct rxe_task *task)
{
tasklet_disable(&task->tasklet);
}
void rxe_enable_task(struct rxe_task *task)
{
tasklet_enable(&task->tasklet);
}
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