/*      $NetBSD: rf_revent.c,v 1.29 2021/07/23 00:54:45 oster Exp $     */
/*
* Copyright (c) 1995 Carnegie-Mellon University.
* All rights reserved.
*
* Author:
*
* Permission to use, copy, modify and distribute this software and
* its documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
*  Software Distribution Coordinator  or  [email protected]
*  School of Computer Science
*  Carnegie Mellon University
*  Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*/
/*
* revent.c -- reconstruction event handling code
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: rf_revent.c,v 1.29 2021/07/23 00:54:45 oster Exp $");

#include <sys/errno.h>

#include "rf_raid.h"
#include "rf_revent.h"
#include "rf_etimer.h"
#include "rf_general.h"
#include "rf_desc.h"
#include "rf_shutdown.h"

#define RF_MAX_FREE_REVENT 128
#define RF_MIN_FREE_REVENT  32
#define RF_EVENTQ_WAIT 5000

#include <sys/proc.h>
#include <sys/kernel.h>

static void rf_ShutdownReconEvent(void *);

static RF_ReconEvent_t *
GetReconEventDesc(RF_Raid_t *raidPtr, RF_RowCol_t col, void *arg, RF_Revent_t type);

static void rf_ShutdownReconEvent(void *arg)
{
       RF_Raid_t *raidPtr;

       raidPtr = (RF_Raid_t *) arg;

       pool_destroy(&raidPtr->pools.revent);
}

int
rf_ConfigureReconEvent(RF_ShutdownList_t **listp, RF_Raid_t *raidPtr,
                      RF_Config_t *cfgPtr)
{

       rf_pool_init(raidPtr, raidPtr->poolNames.revent, &raidPtr->pools.revent, sizeof(RF_ReconEvent_t),
                    "revent", RF_MIN_FREE_REVENT, RF_MAX_FREE_REVENT);
       rf_ShutdownCreate(listp, rf_ShutdownReconEvent, raidPtr);

       return (0);
}

/* returns the next reconstruction event, blocking the calling thread
* until one becomes available.  will now return null if it is blocked
* or will return an event if it is not */

RF_ReconEvent_t *
rf_GetNextReconEvent(RF_RaidReconDesc_t *reconDesc)
{
       RF_Raid_t *raidPtr = reconDesc->raidPtr;
       RF_ReconCtrl_t *rctrl = raidPtr->reconControl;
       RF_ReconEvent_t *event;
       int stall_count;

       rf_lock_mutex2(rctrl->eq_mutex);
       /* q null and count==0 must be equivalent conditions */
       RF_ASSERT((rctrl->eventQueue == NULL) == (rctrl->eq_count == 0));

       /* mpsleep timeout value: secs = timo_val/hz.  'ticks' here is
          defined as cycle-counter ticks, not softclock ticks */

#define MAX_RECON_EXEC_USECS (100 * 1000)  /* 100 ms */
#define RECON_DELAY_MS 25
#define RECON_TIMO     ((RECON_DELAY_MS * hz) / 1000)

       /* we are not pre-emptible in the kernel, but we don't want to run
        * forever.  If we run w/o blocking for more than MAX_RECON_EXEC_TICKS
        * ticks of the cycle counter, delay for RECON_DELAY before
        * continuing. this may murder us with context switches, so we may
        * need to increase both the MAX...TICKS and the RECON_DELAY_MS. */
       if (reconDesc->reconExecTimerRunning) {
               int     status;

               RF_ETIMER_STOP(reconDesc->recon_exec_timer);
               RF_ETIMER_EVAL(reconDesc->recon_exec_timer);
               reconDesc->reconExecTicks +=
                       RF_ETIMER_VAL_US(reconDesc->recon_exec_timer);
               if (reconDesc->reconExecTicks > reconDesc->maxReconExecTicks)
                       reconDesc->maxReconExecTicks =
                               reconDesc->reconExecTicks;
               if (reconDesc->reconExecTicks >= MAX_RECON_EXEC_USECS) {
                       /* we've been running too long.  delay for
                        * RECON_DELAY_MS */
#if RF_RECON_STATS > 0
                       reconDesc->numReconExecDelays++;
#endif                          /* RF_RECON_STATS > 0 */

                       status = rf_sleep("rfrecond", RECON_TIMO,
                                         rctrl->eq_mutex);
                       RF_ASSERT(status == EWOULDBLOCK);
                       reconDesc->reconExecTicks = 0;
               }
       }

       stall_count = 0;
       while (!rctrl->eventQueue) {
#if RF_RECON_STATS > 0
               reconDesc->numReconEventWaits++;
#endif                          /* RF_RECON_STATS > 0 */

               rf_timedwait_cond2(rctrl->eq_cv, rctrl->eq_mutex,
                                  RF_EVENTQ_WAIT);

               stall_count++;

               if ((stall_count > 10) &&
                   rctrl->headSepCBList) {
                       /* There is work to do on the callback list, and
                          we've waited long enough... */
                       rf_WakeupHeadSepCBWaiters(raidPtr);
                       stall_count = 0;
               }
               reconDesc->reconExecTicks = 0;  /* we've just waited */
       }

       reconDesc->reconExecTimerRunning = 1;
       if (RF_ETIMER_VAL_US(reconDesc->recon_exec_timer)!=0) {
               /* it moved!!  reset the timer. */
               RF_ETIMER_START(reconDesc->recon_exec_timer);
       }
       event = rctrl->eventQueue;
       rctrl->eventQueue = event->next;
       event->next = NULL;
       rctrl->eq_count--;

       /* q null and count==0 must be equivalent conditions */
       RF_ASSERT((rctrl->eventQueue == NULL) == (rctrl->eq_count == 0));
       rf_unlock_mutex2(rctrl->eq_mutex);
       return (event);
}
/* enqueues a reconstruction event on the indicated queue */
void
rf_CauseReconEvent(RF_Raid_t *raidPtr, RF_RowCol_t col, void *arg,
                  RF_Revent_t type)
{
       RF_ReconCtrl_t *rctrl = raidPtr->reconControl;
       RF_ReconEvent_t *event = GetReconEventDesc(raidPtr, col, arg, type);

       if (type == RF_REVENT_BUFCLEAR) {
               RF_ASSERT(col != rctrl->fcol);
       }
       RF_ASSERT(col >= 0 && col <= raidPtr->numCol);
       rf_lock_mutex2(rctrl->eq_mutex);
       /* q null and count==0 must be equivalent conditions */
       RF_ASSERT((rctrl->eventQueue == NULL) == (rctrl->eq_count == 0));
       event->next = rctrl->eventQueue;
       rctrl->eventQueue = event;
       rctrl->eq_count++;
       rf_broadcast_cond2(rctrl->eq_cv);
       rf_unlock_mutex2(rctrl->eq_mutex);
}
/* allocates and initializes a recon event descriptor */
static RF_ReconEvent_t *
GetReconEventDesc(RF_Raid_t *raidPtr, RF_RowCol_t col, void *arg, RF_Revent_t type)
{
       RF_ReconEvent_t *t;

       t = pool_get(&raidPtr->pools.revent, PR_WAITOK);
       t->col = col;
       t->arg = arg;
       t->type = type;
       t->next = NULL;
       return (t);
}

/*
 rf_DrainReconEventQueue() -- used in the event of a reconstruction
 problem, this function simply drains all pending events from the
 reconstruct event queue.
*/

void
rf_DrainReconEventQueue(RF_RaidReconDesc_t *reconDesc)
{
       RF_ReconCtrl_t *rctrl = reconDesc->raidPtr->reconControl;
       RF_ReconEvent_t *event;

       rf_lock_mutex2(rctrl->eq_mutex);
       while (rctrl->eventQueue!=NULL) {

               event = rctrl->eventQueue;
               rctrl->eventQueue = event->next;
               event->next = NULL;
               rctrl->eq_count--;
               /* dump it */
               rf_FreeReconEventDesc(reconDesc->raidPtr, event);
       }
       rf_unlock_mutex2(rctrl->eq_mutex);
}

void
rf_FreeReconEventDesc(RF_Raid_t *raidPtr, RF_ReconEvent_t *event)
{
       pool_put(&raidPtr->pools.revent, event);
}

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