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NetBSD/sys/dev/raidframe/rf_engine.c
oster 3995c18b9e Remove incorrect comment.
2002-07-14 03:04:02 +00:00

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/* $NetBSD: rf_engine.c,v 1.15 2002/07/14 03:04:02 oster Exp $ */
/*
* Copyright (c) 1995 Carnegie-Mellon University.
* All rights reserved.
*
* Author: William V. Courtright II, Mark Holland, Rachad Youssef
*
* 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.
*/
/****************************************************************************
* *
* engine.c -- code for DAG execution engine *
* *
* Modified to work as follows (holland): *
* A user-thread calls into DispatchDAG, which fires off the nodes that *
* are direct successors to the header node. DispatchDAG then returns, *
* and the rest of the I/O continues asynchronously. As each node *
* completes, the node execution function calls FinishNode(). FinishNode *
* scans the list of successors to the node and increments the antecedent *
* counts. Each node that becomes enabled is placed on a central node *
* queue. A dedicated dag-execution thread grabs nodes off of this *
* queue and fires them. *
* *
* NULL nodes are never fired. *
* *
* Terminator nodes are never fired, but rather cause the callback *
* associated with the DAG to be invoked. *
* *
* If a node fails, the dag either rolls forward to the completion or *
* rolls back, undoing previously-completed nodes and fails atomically. *
* The direction of recovery is determined by the location of the failed *
* node in the graph. If the failure occurred before the commit node in *
* the graph, backward recovery is used. Otherwise, forward recovery is *
* used. *
* *
****************************************************************************/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: rf_engine.c,v 1.15 2002/07/14 03:04:02 oster Exp $");
#include "rf_threadstuff.h"
#include <sys/errno.h>
#include "rf_dag.h"
#include "rf_engine.h"
#include "rf_etimer.h"
#include "rf_general.h"
#include "rf_dagutils.h"
#include "rf_shutdown.h"
#include "rf_raid.h"
static void DAGExecutionThread(RF_ThreadArg_t arg);
#define DO_INIT(_l_,_r_) { \
int _rc; \
_rc = rf_create_managed_mutex(_l_,&(_r_)->node_queue_mutex); \
if (_rc) { \
return(_rc); \
} \
_rc = rf_create_managed_cond(_l_,&(_r_)->node_queue_cond); \
if (_rc) { \
return(_rc); \
} \
}
/* synchronization primitives for this file. DO_WAIT should be enclosed in a while loop. */
/*
* XXX Is this spl-ing really necessary?
*/
#define DO_LOCK(_r_) \
do { \
ks = splbio(); \
RF_LOCK_MUTEX((_r_)->node_queue_mutex); \
} while (0)
#define DO_UNLOCK(_r_) \
do { \
RF_UNLOCK_MUTEX((_r_)->node_queue_mutex); \
splx(ks); \
} while (0)
#define DO_WAIT(_r_) \
RF_WAIT_COND((_r_)->node_queue, (_r_)->node_queue_mutex)
#define DO_SIGNAL(_r_) \
RF_BROADCAST_COND((_r_)->node_queue) /* XXX RF_SIGNAL_COND? */
static void rf_ShutdownEngine(void *);
static void
rf_ShutdownEngine(arg)
void *arg;
{
RF_Raid_t *raidPtr;
raidPtr = (RF_Raid_t *) arg;
raidPtr->shutdown_engine = 1;
DO_SIGNAL(raidPtr);
}
int
rf_ConfigureEngine(
RF_ShutdownList_t ** listp,
RF_Raid_t * raidPtr,
RF_Config_t * cfgPtr)
{
int rc;
DO_INIT(listp, raidPtr);
raidPtr->node_queue = NULL;
raidPtr->dags_in_flight = 0;
rc = rf_init_managed_threadgroup(listp, &raidPtr->engine_tg);
if (rc)
return (rc);
/* we create the execution thread only once per system boot. no need
* to check return code b/c the kernel panics if it can't create the
* thread. */
if (rf_engineDebug) {
printf("raid%d: Creating engine thread\n", raidPtr->raidid);
}
if (RF_CREATE_THREAD(raidPtr->engine_thread, DAGExecutionThread, raidPtr,"raid")) {
RF_ERRORMSG("RAIDFRAME: Unable to create engine thread\n");
return (ENOMEM);
}
if (rf_engineDebug) {
printf("raid%d: Created engine thread\n", raidPtr->raidid);
}
RF_THREADGROUP_STARTED(&raidPtr->engine_tg);
/* XXX something is missing here... */
#ifdef debug
printf("Skipping the WAIT_START!!\n");
#endif
#if 0
RF_THREADGROUP_WAIT_START(&raidPtr->engine_tg);
#endif
/* engine thread is now running and waiting for work */
if (rf_engineDebug) {
printf("raid%d: Engine thread running and waiting for events\n", raidPtr->raidid);
}
rc = rf_ShutdownCreate(listp, rf_ShutdownEngine, raidPtr);
if (rc) {
RF_ERRORMSG3("Unable to add to shutdown list file %s line %d rc=%d\n", __FILE__,
__LINE__, rc);
rf_ShutdownEngine(NULL);
}
return (rc);
}
static int
BranchDone(RF_DagNode_t * node)
{
int i;
/* return true if forward execution is completed for a node and it's
* succedents */
switch (node->status) {
case rf_wait:
/* should never be called in this state */
RF_PANIC();
break;
case rf_fired:
/* node is currently executing, so we're not done */
return (RF_FALSE);
case rf_good:
for (i = 0; i < node->numSuccedents; i++) /* for each succedent */
if (!BranchDone(node->succedents[i])) /* recursively check
* branch */
return RF_FALSE;
return RF_TRUE; /* node and all succedent branches aren't in
* fired state */
break;
case rf_bad:
/* succedents can't fire */
return (RF_TRUE);
case rf_recover:
/* should never be called in this state */
RF_PANIC();
break;
case rf_undone:
case rf_panic:
/* XXX need to fix this case */
/* for now, assume that we're done */
return (RF_TRUE);
break;
default:
/* illegal node status */
RF_PANIC();
break;
}
}
static int
NodeReady(RF_DagNode_t * node)
{
int ready;
switch (node->dagHdr->status) {
case rf_enable:
case rf_rollForward:
if ((node->status == rf_wait) && (node->numAntecedents == node->numAntDone))
ready = RF_TRUE;
else
ready = RF_FALSE;
break;
case rf_rollBackward:
RF_ASSERT(node->numSuccDone <= node->numSuccedents);
RF_ASSERT(node->numSuccFired <= node->numSuccedents);
RF_ASSERT(node->numSuccFired <= node->numSuccDone);
if ((node->status == rf_good) && (node->numSuccDone == node->numSuccedents))
ready = RF_TRUE;
else
ready = RF_FALSE;
break;
default:
printf("Execution engine found illegal DAG status in NodeReady\n");
RF_PANIC();
break;
}
return (ready);
}
/* user context and dag-exec-thread context:
* Fire a node. The node's status field determines which function, do or undo,
* to be fired.
* This routine assumes that the node's status field has alread been set to
* "fired" or "recover" to indicate the direction of execution.
*/
static void
FireNode(RF_DagNode_t * node)
{
switch (node->status) {
case rf_fired:
/* fire the do function of a node */
if (rf_engineDebug) {
printf("raid%d: Firing node 0x%lx (%s)\n",
node->dagHdr->raidPtr->raidid,
(unsigned long) node, node->name);
}
if (node->flags & RF_DAGNODE_FLAG_YIELD) {
#if defined(__NetBSD__) && defined(_KERNEL)
/* thread_block(); */
/* printf("Need to block the thread here...\n"); */
/* XXX thread_block is actually mentioned in
* /usr/include/vm/vm_extern.h */
#else
thread_block();
#endif
}
(*(node->doFunc)) (node);
break;
case rf_recover:
/* fire the undo function of a node */
if (rf_engineDebug) {
printf("raid%d: Firing (undo) node 0x%lx (%s)\n",
node->dagHdr->raidPtr->raidid,
(unsigned long) node, node->name);
}
if (node->flags & RF_DAGNODE_FLAG_YIELD)
#if defined(__NetBSD__) && defined(_KERNEL)
/* thread_block(); */
/* printf("Need to block the thread here...\n"); */
/* XXX thread_block is actually mentioned in
* /usr/include/vm/vm_extern.h */
#else
thread_block();
#endif
(*(node->undoFunc)) (node);
break;
default:
RF_PANIC();
break;
}
}
/* user context:
* Attempt to fire each node in a linear array.
* The entire list is fired atomically.
*/
static void
FireNodeArray(
int numNodes,
RF_DagNode_t ** nodeList)
{
RF_DagStatus_t dstat;
RF_DagNode_t *node;
int i, j;
/* first, mark all nodes which are ready to be fired */
for (i = 0; i < numNodes; i++) {
node = nodeList[i];
dstat = node->dagHdr->status;
RF_ASSERT((node->status == rf_wait) || (node->status == rf_good));
if (NodeReady(node)) {
if ((dstat == rf_enable) || (dstat == rf_rollForward)) {
RF_ASSERT(node->status == rf_wait);
if (node->commitNode)
node->dagHdr->numCommits++;
node->status = rf_fired;
for (j = 0; j < node->numAntecedents; j++)
node->antecedents[j]->numSuccFired++;
} else {
RF_ASSERT(dstat == rf_rollBackward);
RF_ASSERT(node->status == rf_good);
RF_ASSERT(node->commitNode == RF_FALSE); /* only one commit node
* per graph */
node->status = rf_recover;
}
}
}
/* now, fire the nodes */
for (i = 0; i < numNodes; i++) {
if ((nodeList[i]->status == rf_fired) || (nodeList[i]->status == rf_recover))
FireNode(nodeList[i]);
}
}
/* user context:
* Attempt to fire each node in a linked list.
* The entire list is fired atomically.
*/
static void
FireNodeList(RF_DagNode_t * nodeList)
{
RF_DagNode_t *node, *next;
RF_DagStatus_t dstat;
int j;
if (nodeList) {
/* first, mark all nodes which are ready to be fired */
for (node = nodeList; node; node = next) {
next = node->next;
dstat = node->dagHdr->status;
RF_ASSERT((node->status == rf_wait) || (node->status == rf_good));
if (NodeReady(node)) {
if ((dstat == rf_enable) || (dstat == rf_rollForward)) {
RF_ASSERT(node->status == rf_wait);
if (node->commitNode)
node->dagHdr->numCommits++;
node->status = rf_fired;
for (j = 0; j < node->numAntecedents; j++)
node->antecedents[j]->numSuccFired++;
} else {
RF_ASSERT(dstat == rf_rollBackward);
RF_ASSERT(node->status == rf_good);
RF_ASSERT(node->commitNode == RF_FALSE); /* only one commit node
* per graph */
node->status = rf_recover;
}
}
}
/* now, fire the nodes */
for (node = nodeList; node; node = next) {
next = node->next;
if ((node->status == rf_fired) || (node->status == rf_recover))
FireNode(node);
}
}
}
/* interrupt context:
* for each succedent
* propagate required results from node to succedent
* increment succedent's numAntDone
* place newly-enable nodes on node queue for firing
*
* To save context switches, we don't place NIL nodes on the node queue,
* but rather just process them as if they had fired. Note that NIL nodes
* that are the direct successors of the header will actually get fired by
* DispatchDAG, which is fine because no context switches are involved.
*
* Important: when running at user level, this can be called by any
* disk thread, and so the increment and check of the antecedent count
* must be locked. I used the node queue mutex and locked down the
* entire function, but this is certainly overkill.
*/
static void
PropagateResults(
RF_DagNode_t * node,
int context)
{
RF_DagNode_t *s, *a;
RF_Raid_t *raidPtr;
int i, ks;
RF_DagNode_t *finishlist = NULL; /* a list of NIL nodes to be
* finished */
RF_DagNode_t *skiplist = NULL; /* list of nodes with failed truedata
* antecedents */
RF_DagNode_t *firelist = NULL; /* a list of nodes to be fired */
RF_DagNode_t *q = NULL, *qh = NULL, *next;
int j, skipNode;
raidPtr = node->dagHdr->raidPtr;
DO_LOCK(raidPtr);
/* debug - validate fire counts */
for (i = 0; i < node->numAntecedents; i++) {
a = *(node->antecedents + i);
RF_ASSERT(a->numSuccFired >= a->numSuccDone);
RF_ASSERT(a->numSuccFired <= a->numSuccedents);
a->numSuccDone++;
}
switch (node->dagHdr->status) {
case rf_enable:
case rf_rollForward:
for (i = 0; i < node->numSuccedents; i++) {
s = *(node->succedents + i);
RF_ASSERT(s->status == rf_wait);
(s->numAntDone)++;
if (s->numAntDone == s->numAntecedents) {
/* look for NIL nodes */
if (s->doFunc == rf_NullNodeFunc) {
/* don't fire NIL nodes, just process
* them */
s->next = finishlist;
finishlist = s;
} else {
/* look to see if the node is to be
* skipped */
skipNode = RF_FALSE;
for (j = 0; j < s->numAntecedents; j++)
if ((s->antType[j] == rf_trueData) && (s->antecedents[j]->status == rf_bad))
skipNode = RF_TRUE;
if (skipNode) {
/* this node has one or more
* failed true data
* dependencies, so skip it */
s->next = skiplist;
skiplist = s;
} else
/* add s to list of nodes (q)
* to execute */
if (context != RF_INTR_CONTEXT) {
/* we only have to
* enqueue if we're at
* intr context */
s->next = firelist; /* put node on a list to
* be fired after we
* unlock */
firelist = s;
} else { /* enqueue the node for
* the dag exec thread
* to fire */
RF_ASSERT(NodeReady(s));
if (q) {
q->next = s;
q = s;
} else {
qh = q = s;
qh->next = NULL;
}
}
}
}
}
if (q) {
/* xfer our local list of nodes to the node queue */
q->next = raidPtr->node_queue;
raidPtr->node_queue = qh;
DO_SIGNAL(raidPtr);
}
DO_UNLOCK(raidPtr);
for (; skiplist; skiplist = next) {
next = skiplist->next;
skiplist->status = rf_skipped;
for (i = 0; i < skiplist->numAntecedents; i++) {
skiplist->antecedents[i]->numSuccFired++;
}
if (skiplist->commitNode) {
skiplist->dagHdr->numCommits++;
}
rf_FinishNode(skiplist, context);
}
for (; finishlist; finishlist = next) {
/* NIL nodes: no need to fire them */
next = finishlist->next;
finishlist->status = rf_good;
for (i = 0; i < finishlist->numAntecedents; i++) {
finishlist->antecedents[i]->numSuccFired++;
}
if (finishlist->commitNode)
finishlist->dagHdr->numCommits++;
/*
* Okay, here we're calling rf_FinishNode() on nodes that
* have the null function as their work proc. Such a node
* could be the terminal node in a DAG. If so, it will
* cause the DAG to complete, which will in turn free
* memory used by the DAG, which includes the node in
* question. Thus, we must avoid referencing the node
* at all after calling rf_FinishNode() on it.
*/
rf_FinishNode(finishlist, context); /* recursive call */
}
/* fire all nodes in firelist */
FireNodeList(firelist);
break;
case rf_rollBackward:
for (i = 0; i < node->numAntecedents; i++) {
a = *(node->antecedents + i);
RF_ASSERT(a->status == rf_good);
RF_ASSERT(a->numSuccDone <= a->numSuccedents);
RF_ASSERT(a->numSuccDone <= a->numSuccFired);
if (a->numSuccDone == a->numSuccFired) {
if (a->undoFunc == rf_NullNodeFunc) {
/* don't fire NIL nodes, just process
* them */
a->next = finishlist;
finishlist = a;
} else {
if (context != RF_INTR_CONTEXT) {
/* we only have to enqueue if
* we're at intr context */
a->next = firelist; /* put node on a list to
* be fired after we
* unlock */
firelist = a;
} else { /* enqueue the node for
* the dag exec thread
* to fire */
RF_ASSERT(NodeReady(a));
if (q) {
q->next = a;
q = a;
} else {
qh = q = a;
qh->next = NULL;
}
}
}
}
}
if (q) {
/* xfer our local list of nodes to the node queue */
q->next = raidPtr->node_queue;
raidPtr->node_queue = qh;
DO_SIGNAL(raidPtr);
}
DO_UNLOCK(raidPtr);
for (; finishlist; finishlist = next) { /* NIL nodes: no need to
* fire them */
next = finishlist->next;
finishlist->status = rf_good;
/*
* Okay, here we're calling rf_FinishNode() on nodes that
* have the null function as their work proc. Such a node
* could be the first node in a DAG. If so, it will
* cause the DAG to complete, which will in turn free
* memory used by the DAG, which includes the node in
* question. Thus, we must avoid referencing the node
* at all after calling rf_FinishNode() on it.
*/
rf_FinishNode(finishlist, context); /* recursive call */
}
/* fire all nodes in firelist */
FireNodeList(firelist);
break;
default:
printf("Engine found illegal DAG status in PropagateResults()\n");
RF_PANIC();
break;
}
}
/*
* Process a fired node which has completed
*/
static void
ProcessNode(
RF_DagNode_t * node,
int context)
{
RF_Raid_t *raidPtr;
raidPtr = node->dagHdr->raidPtr;
switch (node->status) {
case rf_good:
/* normal case, don't need to do anything */
break;
case rf_bad:
if ((node->dagHdr->numCommits > 0) || (node->dagHdr->numCommitNodes == 0)) {
node->dagHdr->status = rf_rollForward; /* crossed commit
* barrier */
if (rf_engineDebug || 1) {
printf("raid%d: node (%s) returned fail, rolling forward\n", raidPtr->raidid, node->name);
}
} else {
node->dagHdr->status = rf_rollBackward; /* never reached commit
* barrier */
if (rf_engineDebug || 1) {
printf("raid%d: node (%s) returned fail, rolling backward\n", raidPtr->raidid, node->name);
}
}
break;
case rf_undone:
/* normal rollBackward case, don't need to do anything */
break;
case rf_panic:
/* an undo node failed!!! */
printf("UNDO of a node failed!!!/n");
break;
default:
printf("node finished execution with an illegal status!!!\n");
RF_PANIC();
break;
}
/* enqueue node's succedents (antecedents if rollBackward) for
* execution */
PropagateResults(node, context);
}
/* user context or dag-exec-thread context:
* This is the first step in post-processing a newly-completed node.
* This routine is called by each node execution function to mark the node
* as complete and fire off any successors that have been enabled.
*/
int
rf_FinishNode(
RF_DagNode_t * node,
int context)
{
int retcode = RF_FALSE;
node->dagHdr->numNodesCompleted++;
ProcessNode(node, context);
return (retcode);
}
/* user context:
* submit dag for execution, return non-zero if we have to wait for completion.
* if and only if we return non-zero, we'll cause cbFunc to get invoked with
* cbArg when the DAG has completed.
*
* for now we always return 1. If the DAG does not cause any I/O, then the callback
* may get invoked before DispatchDAG returns. There's code in state 5 of ContinueRaidAccess
* to handle this.
*
* All we do here is fire the direct successors of the header node. The
* DAG execution thread does the rest of the dag processing.
*/
int
rf_DispatchDAG(
RF_DagHeader_t * dag,
void (*cbFunc) (void *),
void *cbArg)
{
RF_Raid_t *raidPtr;
raidPtr = dag->raidPtr;
if (dag->tracerec) {
RF_ETIMER_START(dag->tracerec->timer);
}
#if DEBUG
#if RF_DEBUG_VALIDATE_DAG
if (rf_engineDebug || rf_validateDAGDebug) {
if (rf_ValidateDAG(dag))
RF_PANIC();
}
#endif
#endif
if (rf_engineDebug) {
printf("raid%d: Entering DispatchDAG\n", raidPtr->raidid);
}
raidPtr->dags_in_flight++; /* debug only: blow off proper
* locking */
dag->cbFunc = cbFunc;
dag->cbArg = cbArg;
dag->numNodesCompleted = 0;
dag->status = rf_enable;
FireNodeArray(dag->numSuccedents, dag->succedents);
return (1);
}
/* dedicated kernel thread:
* the thread that handles all DAG node firing.
* To minimize locking and unlocking, we grab a copy of the entire node queue and then set the
* node queue to NULL before doing any firing of nodes. This way we only have to release the
* lock once. Of course, it's probably rare that there's more than one node in the queue at
* any one time, but it sometimes happens.
*
* In the kernel, this thread runs at spl0 and is not swappable. I copied these
* characteristics from the aio_completion_thread.
*/
static void
DAGExecutionThread(RF_ThreadArg_t arg)
{
RF_DagNode_t *nd, *local_nq, *term_nq, *fire_nq;
RF_Raid_t *raidPtr;
int ks;
int s;
raidPtr = (RF_Raid_t *) arg;
if (rf_engineDebug) {
printf("raid%d: Engine thread is running\n", raidPtr->raidid);
}
s = splbio();
RF_THREADGROUP_RUNNING(&raidPtr->engine_tg);
DO_LOCK(raidPtr);
while (!raidPtr->shutdown_engine) {
while (raidPtr->node_queue != NULL) {
local_nq = raidPtr->node_queue;
fire_nq = NULL;
term_nq = NULL;
raidPtr->node_queue = NULL;
DO_UNLOCK(raidPtr);
/* first, strip out the terminal nodes */
while (local_nq) {
nd = local_nq;
local_nq = local_nq->next;
switch (nd->dagHdr->status) {
case rf_enable:
case rf_rollForward:
if (nd->numSuccedents == 0) {
/* end of the dag, add to
* callback list */
nd->next = term_nq;
term_nq = nd;
} else {
/* not the end, add to the
* fire queue */
nd->next = fire_nq;
fire_nq = nd;
}
break;
case rf_rollBackward:
if (nd->numAntecedents == 0) {
/* end of the dag, add to the
* callback list */
nd->next = term_nq;
term_nq = nd;
} else {
/* not the end, add to the
* fire queue */
nd->next = fire_nq;
fire_nq = nd;
}
break;
default:
RF_PANIC();
break;
}
}
/* execute callback of dags which have reached the
* terminal node */
while (term_nq) {
nd = term_nq;
term_nq = term_nq->next;
nd->next = NULL;
(nd->dagHdr->cbFunc) (nd->dagHdr->cbArg);
raidPtr->dags_in_flight--; /* debug only */
}
/* fire remaining nodes */
FireNodeList(fire_nq);
DO_LOCK(raidPtr);
}
while (!raidPtr->shutdown_engine && raidPtr->node_queue == NULL)
DO_WAIT(raidPtr);
}
DO_UNLOCK(raidPtr);
RF_THREADGROUP_DONE(&raidPtr->engine_tg);
splx(s);
kthread_exit(0);
}
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