drivers/staging/greybus/svc_watchdog.c

   1 /*
   2  * SVC Greybus "watchdog" driver.
   3  *
   4  * Copyright 2016 Google Inc.
   5  *
   6  * Released under the GPLv2 only.
   7  */
   8
   9 #include <linux/delay.h>
  10 #include <linux/workqueue.h>
  11 #include "greybus.h"
  12
  13 #define SVC_WATCHDOG_PERIOD     (2*HZ)
  14
  15 struct gb_svc_watchdog {
  16         struct delayed_work     work;
  17         struct gb_svc           *svc;
  18         bool                    finished;
  19 };
  20
  21 static struct delayed_work reset_work;
  22
  23 static void greybus_reset(struct work_struct *work)
  24 {
  25         static char start_path[256] = "/system/bin/start";
  26         static char *envp[] = {
  27                 "HOME=/",
  28                 "PATH=/sbin:/vendor/bin:/system/sbin:/system/bin:/system/xbin",
  29                 NULL,
  30         };
  31         static char *argv[] = {
  32                 start_path,
  33                 "unipro_reset",
  34                 NULL,
  35         };
  36
  37         printk(KERN_ERR "svc_watchdog: calling \"%s %s\" to reset greybus network!\n",
  38                argv[0], argv[1]);
  39         call_usermodehelper(start_path, argv, envp, UMH_WAIT_EXEC);
  40 }
  41
  42 static void do_work(struct work_struct *work)
  43 {
  44         struct gb_svc_watchdog *watchdog;
  45         struct gb_svc *svc;
  46         int retval;
  47
  48         watchdog = container_of(work, struct gb_svc_watchdog, work.work);
  49         svc = watchdog->svc;
  50
  51         dev_dbg(&svc->dev, "%s: ping.\n", __func__);
  52         retval = gb_svc_ping(svc);
  53         if (retval) {
  54                 /*
  55                  * Something went really wrong, let's warn userspace and then
  56                  * pull the plug and reset the whole greybus network.
  57                  * We need to do this outside of this workqueue as we will be
  58                  * tearing down the svc device itself.  So queue up
  59                  * yet-another-callback to do that.
  60                  */
  61                 dev_err(&svc->dev,
  62                         "SVC ping has returned %d, something is wrong!!!\n",
  63                         retval);
  64                 dev_err(&svc->dev, "Resetting the greybus network, watch out!!!\n");
  65
  66                 INIT_DELAYED_WORK(&reset_work, greybus_reset);
  67                 queue_delayed_work(system_wq, &reset_work, HZ/2);
  68                 return;
  69         }
  70
  71         /* resubmit our work to happen again, if we are still "alive" */
  72         if (!watchdog->finished)
  73                 queue_delayed_work(system_wq, &watchdog->work,
  74                                    SVC_WATCHDOG_PERIOD);
  75 }
  76
  77 int gb_svc_watchdog_create(struct gb_svc *svc)
  78 {
  79         struct gb_svc_watchdog *watchdog;
  80
  81         if (svc->watchdog)
  82                 return 0;
  83
  84         watchdog = kmalloc(sizeof(*watchdog), GFP_KERNEL);
  85         if (!watchdog)
  86                 return -ENOMEM;
  87
  88         watchdog->finished = false;
  89         watchdog->svc = svc;
  90         INIT_DELAYED_WORK(&watchdog->work, do_work);
  91         svc->watchdog = watchdog;
  92
  93         queue_delayed_work(system_wq, &watchdog->work,
  94                            SVC_WATCHDOG_PERIOD);
  95         return 0;
  96 }
  97
  98 void gb_svc_watchdog_destroy(struct gb_svc *svc)
  99 {
 100         struct gb_svc_watchdog *watchdog = svc->watchdog;
 101
 102         if (!watchdog)
 103                 return;
 104
 105         watchdog->finished = true;
 106         cancel_delayed_work_sync(&watchdog->work);
 107         svc->watchdog = NULL;
 108         kfree(watchdog);
 109 }