drivers/infiniband/sw/rxe/rxe_task.c

   1 /*
   2  * Copyright (c) 2016 Mellanox Technologies Ltd. All rights reserved.
   3  * Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.
   4  *
   5  * This software is available to you under a choice of one of two
   6  * licenses.  You may choose to be licensed under the terms of the GNU
   7  * General Public License (GPL) Version 2, available from the file
   8  * COPYING in the main directory of this source tree, or the
   9  * OpenIB.org BSD license below:
  10  *
  11  *         Redistribution and use in source and binary forms, with or
  12  *         without modification, are permitted provided that the following
  13  *         conditions are met:
  14  *
  15  *      - Redistributions of source code must retain the above
  16  *        copyright notice, this list of conditions and the following
  17  *        disclaimer.
  18  *
  19  *      - Redistributions in binary form must reproduce the above
  20  *        copyright notice, this list of conditions and the following
  21  *        disclaimer in the documentation and/or other materials
  22  *        provided with the distribution.
  23  *
  24  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  25  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  26  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  27  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  28  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  29  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  30  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  31  * SOFTWARE.
  32  */
  33
  34 #include <linux/kernel.h>
  35 #include <linux/interrupt.h>
  36 #include <linux/hardirq.h>
  37
  38 #include "rxe_task.h"
  39
  40 int __rxe_do_task(struct rxe_task *task)
  41
  42 {
  43         int ret;
  44
  45         while ((ret = task->func(task->arg)) == 0)
  46                 ;
  47
  48         task->ret = ret;
  49
  50         return ret;
  51 }
  52
  53 /*
  54  * this locking is due to a potential race where
  55  * a second caller finds the task already running
  56  * but looks just after the last call to func
  57  */
  58 void rxe_do_task(unsigned long data)
  59 {
  60         int cont;
  61         int ret;
  62         unsigned long flags;
  63         struct rxe_task *task = (struct rxe_task *)data;
  64
  65         spin_lock_irqsave(&task->state_lock, flags);
  66         switch (task->state) {
  67         case TASK_STATE_START:
  68                 task->state = TASK_STATE_BUSY;
  69                 spin_unlock_irqrestore(&task->state_lock, flags);
  70                 break;
  71
  72         case TASK_STATE_BUSY:
  73                 task->state = TASK_STATE_ARMED;
  74                 /* fall through to */
  75         case TASK_STATE_ARMED:
  76                 spin_unlock_irqrestore(&task->state_lock, flags);
  77                 return;
  78
  79         default:
  80                 spin_unlock_irqrestore(&task->state_lock, flags);
  81                 pr_warn("bad state = %d in rxe_do_task\n", task->state);
  82                 return;
  83         }
  84
  85         do {
  86                 cont = 0;
  87                 ret = task->func(task->arg);
  88
  89                 spin_lock_irqsave(&task->state_lock, flags);
  90                 switch (task->state) {
  91                 case TASK_STATE_BUSY:
  92                         if (ret)
  93                                 task->state = TASK_STATE_START;
  94                         else
  95                                 cont = 1;
  96                         break;
  97
  98                 /* soneone tried to run the task since the last time we called
  99                  * func, so we will call one more time regardless of the
 100                  * return value
 101                  */
 102                 case TASK_STATE_ARMED:
 103                         task->state = TASK_STATE_BUSY;
 104                         cont = 1;
 105                         break;
 106
 107                 default:
 108                         pr_warn("bad state = %d in rxe_do_task\n",
 109                                 task->state);
 110                 }
 111                 spin_unlock_irqrestore(&task->state_lock, flags);
 112         } while (cont);
 113
 114         task->ret = ret;
 115 }
 116
 117 int rxe_init_task(void *obj, struct rxe_task *task,
 118                   void *arg, int (*func)(void *), char *name)
 119 {
 120         task->obj       = obj;
 121         task->arg       = arg;
 122         task->func      = func;
 123         snprintf(task->name, sizeof(task->name), "%s", name);
 124
 125         tasklet_init(&task->tasklet, rxe_do_task, (unsigned long)task);
 126
 127         task->state = TASK_STATE_START;
 128         spin_lock_init(&task->state_lock);
 129
 130         return 0;
 131 }
 132
 133 void rxe_cleanup_task(struct rxe_task *task)
 134 {
 135         tasklet_kill(&task->tasklet);
 136 }
 137
 138 void rxe_run_task(struct rxe_task *task, int sched)
 139 {
 140         if (sched)
 141                 tasklet_schedule(&task->tasklet);
 142         else
 143                 rxe_do_task((unsigned long)task);
 144 }
 145
 146 void rxe_disable_task(struct rxe_task *task)
 147 {
 148         tasklet_disable(&task->tasklet);
 149 }
 150
 151 void rxe_enable_task(struct rxe_task *task)
 152 {
 153         tasklet_enable(&task->tasklet);
 154 }