minix/lib/libblockdriver/liveupdate.c

   1 /* This file implements SEF hooks for live update of multithreaded block
   2  * drivers.
   3  */
   4
   5 #include <minix/drivers.h>
   6 #include <minix/blockdriver_mt.h>
   7
   8 #include "driver_mt.h"
   9
  10 /*===========================================================================*
  11  *                              sef_cb_lu_prepare                            *
  12  *===========================================================================*/
  13 static int sef_cb_lu_prepare(int state)
  14 {
  15 /* This function is called to decide whether we can enter the given live
  16  * update state, and to prepare for such an update. If we are requested to
  17  * update to a request-free or protocol-free state, make sure there is no work
  18  * pending or being processed, and shut down all worker threads.
  19  */
  20
  21   switch (state) {
  22   case SEF_LU_STATE_REQUEST_FREE:
  23   case SEF_LU_STATE_PROTOCOL_FREE:
  24         if (!blockdriver_mt_is_idle()) {
  25                 printf("libblockdriver(%d): not idle, blocking update\n",
  26                     sef_self());
  27                 break;
  28         }
  29
  30         blockdriver_mt_suspend();
  31
  32         return OK;
  33   }
  34
  35   return ENOTREADY;
  36 }
  37
  38 /*===========================================================================*
  39  *                              sef_cb_lu_state_changed                      *
  40  *===========================================================================*/
  41 static void sef_cb_lu_state_changed(int old_state, int state)
  42 {
  43 /* This function is called in the old driver instance when the state changes.
  44  * We use it to resume normal operation after a failed live update.
  45  */
  46
  47   if (state != SEF_LU_STATE_NULL)
  48         return;
  49
  50   switch (old_state) {
  51   case SEF_LU_STATE_REQUEST_FREE:
  52   case SEF_LU_STATE_PROTOCOL_FREE:
  53         blockdriver_mt_resume();
  54   }
  55 }
  56
  57 /*===========================================================================*
  58  *                              sef_cb_init_lu                               *
  59  *===========================================================================*/
  60 static int sef_cb_init_lu(int type, sef_init_info_t *info)
  61 {
  62 /* This function is called in the new driver instance during a live update.
  63  */
  64   int r;
  65
  66   /* Perform regular state transfer. */
  67   if ((r = SEF_CB_INIT_LU_DEFAULT(type, info)) != OK)
  68         return r;
  69
  70   /* Recreate worker threads, if necessary. */
  71   switch (info->prepare_state) {
  72   case SEF_LU_STATE_REQUEST_FREE:
  73   case SEF_LU_STATE_PROTOCOL_FREE:
  74         blockdriver_mt_resume();
  75   }
  76
  77   return OK;
  78 }
  79
  80 /*===========================================================================*
  81  *                              blockdriver_mt_support_lu                    *
  82  *===========================================================================*/
  83 void blockdriver_mt_support_lu(void)
  84 {
  85 /* Enable suppor for live update of this driver. To be called before
  86  * sef_startup().
  87  */
  88
  89   /* Register live update callbacks. */
  90   sef_setcb_init_lu(sef_cb_init_lu);
  91   sef_setcb_lu_prepare(sef_cb_lu_prepare);
  92   sef_setcb_lu_state_changed(sef_cb_lu_state_changed);
  93   sef_setcb_lu_state_isvalid(sef_cb_lu_state_isvalid_standard);
  94 }