/*      $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  Software.Distribution@CS.CMU.EDU
 *  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);
}