--- servers/slapd/overlays/syncprov.c	2007/02/05 22:10:23	1.173
+++ servers/slapd/overlays/syncprov.c	2008/03/19 23:31:42	1.223
@@ -1,8 +1,8 @@
-/* $OpenLDAP: pkg/ldap/servers/slapd/overlays/syncprov.c,v 1.172 2007/02/05 08:19:46 hyc Exp $ */
+/* $OpenLDAP: pkg/ldap/servers/slapd/overlays/syncprov.c,v 1.222 2008/03/19 23:26:14 hyc Exp $ */
 /* syncprov.c - syncrepl provider */
 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
  *
- * Copyright 2004-2007 The OpenLDAP Foundation.
+ * Copyright 2004-2008 The OpenLDAP Foundation.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -131,7 +131,7 @@ typedef struct syncprov_info_t {
 	time_t	si_chklast;	/* time of last checkpoint */
 	Avlnode	*si_mods;	/* entries being modified */
 	sessionlog	*si_logs;
-	ldap_pvt_thread_mutex_t	si_csn_mutex;
+	ldap_pvt_thread_rdwr_t	si_csn_rwlock;
 	ldap_pvt_thread_mutex_t	si_ops_mutex;
 	ldap_pvt_thread_mutex_t	si_mods_mutex;
 } syncprov_info_t;
@@ -404,6 +404,7 @@ syncprov_findbase( Operation *op, fbase_
 		slap_callback cb = {0};
 		Operation fop;
 		SlapReply frs = { REP_RESULT };
+		BackendInfo *bi;
 		int rc;
 
 		fc->fss->s_flags ^= PS_FIND_BASE;
@@ -415,6 +416,7 @@ syncprov_findbase( Operation *op, fbase_
 		fop.o_bd = op->o_bd;
 		fop.o_time = op->o_time;
 		fop.o_tincr = op->o_tincr;
+		bi = op->o_bd->bd_info;
 
 		cb.sc_response = findbase_cb;
 		cb.sc_private = fc;
@@ -432,9 +434,8 @@ syncprov_findbase( Operation *op, fbase_
 		fop.ors_filter = &generic_filter;
 		fop.ors_filterstr = generic_filterstr;
 
-		fop.o_bd->bd_info = on->on_info->oi_orig;
-		rc = fop.o_bd->be_search( &fop, &frs );
-		fop.o_bd->bd_info = (BackendInfo *)on;
+		rc = overlay_op_walk( &fop, &frs, op_search, on->on_info, on );
+		op->o_bd->bd_info = bi;
 	} else {
 		ldap_pvt_thread_mutex_unlock( &fc->fss->s_mutex );
 		fc->fbase = 1;
@@ -584,11 +585,7 @@ syncprov_findcsn( Operation *op, find_cs
 	char cbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
 	struct berval maxcsn;
 	Filter cf;
-#ifdef LDAP_COMP_MATCH
-	AttributeAssertion eq = { NULL, BER_BVNULL, NULL };
-#else
-	AttributeAssertion eq = { NULL, BER_BVNULL };
-#endif
+	AttributeAssertion eq = ATTRIBUTEASSERTION_INIT;
 	fpres_cookie pcookie;
 	sync_control *srs = NULL;
 	struct slap_limits_set fc_limits;
@@ -627,8 +624,11 @@ again:
 				maxid = i;
 			}
 		}
-		fop.ors_filterstr.bv_len = sprintf( buf, "(entryCSN>=%s)",
-			cf.f_av_value.bv_val );
+		fop.ors_filterstr.bv_len = snprintf( buf, sizeof( buf ),
+			"(entryCSN>=%s)", cf.f_av_value.bv_val );
+		if ( fop.ors_filterstr.bv_len < 0 || fop.ors_filterstr.bv_len >= sizeof( buf ) ) {
+			return LDAP_OTHER;
+		}
 		fop.ors_attrsonly = 0;
 		fop.ors_attrs = csn_anlist;
 		fop.ors_slimit = SLAP_NO_LIMIT;
@@ -652,15 +652,19 @@ again:
 		/* Look for exact match the first time */
 		if ( findcsn_retry ) {
 			cf.f_choice = LDAP_FILTER_EQUALITY;
-			fop.ors_filterstr.bv_len = sprintf( buf, "(entryCSN=%s)",
-				cf.f_av_value.bv_val );
+			fop.ors_filterstr.bv_len = snprintf( buf, sizeof( buf ),
+				"(entryCSN=%s)", cf.f_av_value.bv_val );
 		/* On retry, look for <= */
 		} else {
 			cf.f_choice = LDAP_FILTER_LE;
 			fop.ors_limit = &fc_limits;
+			memset( &fc_limits, 0, sizeof( fc_limits ));
 			fc_limits.lms_s_unchecked = 1;
-			fop.ors_filterstr.bv_len = sprintf( buf, "(entryCSN<=%s)",
-				cf.f_av_value.bv_val );
+			fop.ors_filterstr.bv_len = snprintf( buf, sizeof( buf ),
+				"(entryCSN<=%s)", cf.f_av_value.bv_val );
+		}
+		if ( fop.ors_filterstr.bv_len < 0 || fop.ors_filterstr.bv_len >= sizeof( buf ) ) {
+			return LDAP_OTHER;
 		}
 		fop.ors_attrsonly = 1;
 		fop.ors_attrs = slap_anlist_no_attrs;
@@ -692,7 +696,10 @@ again:
 		break;
 	}
 
-	fop.o_bd->bd_info = on->on_info->oi_orig;
+	if ( on->on_next )
+		fop.o_bd->bd_info = (BackendInfo *)on->on_next;
+	else
+		fop.o_bd->bd_info = on->on_info->oi_orig;
 	fop.o_bd->be_search( &fop, &frs );
 	fop.o_bd->bd_info = (BackendInfo *)on;
 
@@ -772,6 +779,8 @@ syncprov_sendresp( Operation *op, opcook
 	BER_BVZERO( &csns[1] );
 	slap_compose_sync_cookie( op, &cookie, csns, so->s_rid, so->s_sid );
 
+	Debug( LDAP_DEBUG_SYNC, "syncprov_sendresp: cookie=%s\n", cookie.bv_val, 0, 0 );
+
 	e_uuid.e_attrs = &a_uuid;
 	a_uuid.a_desc = slap_schema.si_ad_entryUUID;
 	a_uuid.a_nvals = &opc->suuid;
@@ -831,15 +840,16 @@ syncprov_sendresp( Operation *op, opcook
 
 /* Play back queued responses */
 static int
-syncprov_qplay( Operation *op, slap_overinst *on, syncops *so )
+syncprov_qplay( Operation *op, struct re_s *rtask )
 {
+	syncops *so = rtask->arg;
+	slap_overinst *on = LDAP_SLIST_FIRST(&so->s_op->o_extra)->oe_key;
 	syncres *sr;
 	Entry *e;
 	opcookie opc;
 	int rc = 0;
 
 	opc.son = on;
-	op->o_bd->bd_info = (BackendInfo *)on->on_info;
 
 	for (;;) {
 		ldap_pvt_thread_mutex_lock( &so->s_mutex );
@@ -848,10 +858,10 @@ syncprov_qplay( Operation *op, slap_over
 			so->s_res = sr->s_next;
 		if ( !so->s_res )
 			so->s_restail = NULL;
-		ldap_pvt_thread_mutex_unlock( &so->s_mutex );
-
+		/* Exit loop with mutex held */
 		if ( !sr || so->s_op->o_abandon )
 			break;
+		ldap_pvt_thread_mutex_unlock( &so->s_mutex );
 
 		opc.sdn = sr->s_dn;
 		opc.sndn = sr->s_ndn;
@@ -861,7 +871,7 @@ syncprov_qplay( Operation *op, slap_over
 		e = NULL;
 
 		if ( sr->s_mode != LDAP_SYNC_DELETE ) {
-			rc = be_entry_get_rw( op, &opc.sndn, NULL, NULL, 0, &e );
+			rc = overlay_entry_get_ov( op, &opc.sndn, NULL, NULL, 0, &e, on );
 			if ( rc ) {
 				Debug( LDAP_DEBUG_SYNC, "syncprov_qplay: failed to get %s, "
 					"error (%d), ignoring...\n", opc.sndn.bv_val, rc, 0 );
@@ -873,15 +883,29 @@ syncprov_qplay( Operation *op, slap_over
 		rc = syncprov_sendresp( op, &opc, so, &e, sr->s_mode );
 
 		if ( e ) {
-			be_entry_release_rw( op, e, 0 );
+			overlay_entry_release_ov( op, e, 0, on );
 		}
 
 		ch_free( sr );
 
-		if ( rc )
+		if ( rc ) {
+			/* Exit loop with mutex held */
+			ldap_pvt_thread_mutex_lock( &so->s_mutex );
 			break;
+		}
 	}
-	op->o_bd->bd_info = (BackendInfo *)on;
+
+	/* wait until we get explicitly scheduled again */
+	ldap_pvt_thread_mutex_lock( &slapd_rq.rq_mutex );
+	ldap_pvt_runqueue_stoptask( &slapd_rq, rtask );
+	if ( rc == 0 ) {
+		ldap_pvt_runqueue_resched( &slapd_rq, rtask, 1 );
+	} else {
+		/* bail out on any error */
+		ldap_pvt_runqueue_remove( &slapd_rq, rtask );
+	}
+	ldap_pvt_thread_mutex_unlock( &slapd_rq.rq_mutex );
+	ldap_pvt_thread_mutex_unlock( &so->s_mutex );
 	return rc;
 }
 
@@ -891,21 +915,20 @@ syncprov_qtask( void *ctx, void *arg )
 {
 	struct re_s *rtask = arg;
 	syncops *so = rtask->arg;
-	slap_overinst *on = so->s_op->o_private;
 	OperationBuffer opbuf;
 	Operation *op;
 	BackendDB be;
 	int rc;
 
-	op = (Operation *) &opbuf;
+	op = &opbuf.ob_op;
 	*op = *so->s_op;
-	op->o_hdr = (Opheader *)(op+1);
-	op->o_controls = (void **)(op->o_hdr+1);
-	memset( op->o_controls, 0, SLAP_MAX_CIDS * sizeof(void *));
+	op->o_hdr = &opbuf.ob_hdr;
+	op->o_controls = opbuf.ob_controls;
+	memset( op->o_controls, 0, sizeof(opbuf.ob_controls) );
 
 	*op->o_hdr = *so->s_op->o_hdr;
 
-	op->o_tmpmemctx = slap_sl_mem_create(SLAP_SLAB_SIZE, SLAP_SLAB_STACK, ctx);
+	op->o_tmpmemctx = slap_sl_mem_create(SLAP_SLAB_SIZE, SLAP_SLAB_STACK, ctx, 1);
 	op->o_tmpmfuncs = &slap_sl_mfuncs;
 	op->o_threadctx = ctx;
 
@@ -913,25 +936,14 @@ syncprov_qtask( void *ctx, void *arg )
 	be = *so->s_op->o_bd;
 	be.be_flags |= SLAP_DBFLAG_OVERLAY;
 	op->o_bd = &be;
-	op->o_private = NULL;
+	LDAP_SLIST_FIRST(&op->o_extra) = NULL;
 	op->o_callback = NULL;
 
-	rc = syncprov_qplay( op, on, so );
+	rc = syncprov_qplay( op, rtask );
 
 	/* decrement use count... */
 	syncprov_free_syncop( so );
 
-	/* wait until we get explicitly scheduled again */
-	ldap_pvt_thread_mutex_lock( &slapd_rq.rq_mutex );
-	ldap_pvt_runqueue_stoptask( &slapd_rq, rtask );
-	if ( rc == 0 ) {
-		ldap_pvt_runqueue_resched( &slapd_rq, rtask, 1 );
-	} else {
-		/* bail out on any error */
-		ldap_pvt_runqueue_remove( &slapd_rq, rtask );
-	}
-	ldap_pvt_thread_mutex_unlock( &slapd_rq.rq_mutex );
-
 #if 0	/* FIXME: connection_close isn't exported from slapd.
 		 * should it be?
 		 */
@@ -978,15 +990,18 @@ static int
 syncprov_qresp( opcookie *opc, syncops *so, int mode )
 {
 	syncres *sr;
-	int sid;
+	int sid, srsize;
 
 	/* Don't send changes back to their originator */
 	sid = slap_parse_csn_sid( &opc->sctxcsn );
-	if ( sid == so->s_sid )
+	if ( sid >= 0 && sid == so->s_sid )
 		return LDAP_SUCCESS;
 
-	sr = ch_malloc(sizeof(syncres) + opc->suuid.bv_len + 1 +
-		opc->sdn.bv_len + 1 + opc->sndn.bv_len + 1 + opc->sctxcsn.bv_len + 1 );
+	srsize = sizeof(syncres) + opc->suuid.bv_len + 1 +
+		opc->sdn.bv_len + 1 + opc->sndn.bv_len + 1;
+	if ( opc->sctxcsn.bv_len )
+		srsize += opc->sctxcsn.bv_len + 1;
+	sr = ch_malloc( srsize );
 	sr->s_next = NULL;
 	sr->s_dn.bv_val = (char *)(sr + 1);
 	sr->s_dn.bv_len = opc->sdn.bv_len;
@@ -999,9 +1014,13 @@ syncprov_qresp( opcookie *opc, syncops *
 		 opc->sndn.bv_val ) + 1;
 	sr->s_uuid.bv_len = opc->suuid.bv_len;
 	AC_MEMCPY( sr->s_uuid.bv_val, opc->suuid.bv_val, opc->suuid.bv_len );
-	sr->s_csn.bv_val = sr->s_uuid.bv_val + sr->s_uuid.bv_len + 1;
+	if ( opc->sctxcsn.bv_len ) {
+		sr->s_csn.bv_val = sr->s_uuid.bv_val + sr->s_uuid.bv_len + 1;
+		strcpy( sr->s_csn.bv_val, opc->sctxcsn.bv_val );
+	} else {
+		sr->s_csn.bv_val = NULL;
+	}
 	sr->s_csn.bv_len = opc->sctxcsn.bv_len;
-	strcpy( sr->s_csn.bv_val, opc->sctxcsn.bv_val );
 
 	ldap_pvt_thread_mutex_lock( &so->s_mutex );
 	if ( !so->s_res ) {
@@ -1031,7 +1050,7 @@ syncprov_drop_psearch( syncops *so, int
 			ldap_pvt_thread_mutex_lock( &so->s_op->o_conn->c_mutex );
 		so->s_op->o_conn->c_n_ops_executing--;
 		so->s_op->o_conn->c_n_ops_completed++;
-		LDAP_STAILQ_REMOVE( &so->s_op->o_conn->c_ops, so->s_op, slap_op,
+		LDAP_STAILQ_REMOVE( &so->s_op->o_conn->c_ops, so->s_op, Operation,
 			o_next );
 		if ( lock )
 			ldap_pvt_thread_mutex_unlock( &so->s_op->o_conn->c_mutex );
@@ -1098,7 +1117,7 @@ syncprov_matchops( Operation *op, opcook
 
 	fbase_cookie fc;
 	syncops *ss, *sprev, *snext;
-	Entry *e;
+	Entry *e = NULL;
 	Attribute *a;
 	int rc;
 	struct berval newdn;
@@ -1120,15 +1139,13 @@ syncprov_matchops( Operation *op, opcook
 			db = *op->o_bd;
 			op->o_bd = &db;
 		}
-		op->o_bd->bd_info = (BackendInfo *)on->on_info;
-		rc = be_entry_get_rw( op, fc.fdn, NULL, NULL, 0, &e );
+		rc = overlay_entry_get_ov( op, fc.fdn, NULL, NULL, 0, &e, on );
 		/* If we're sending responses now, make a copy and unlock the DB */
 		if ( e && !saveit ) {
 			Entry *e2 = entry_dup( e );
-			be_entry_release_rw( op, e, 0 );
+			overlay_entry_release_ov( op, e, 0, on );
 			e = e2;
 		}
-		op->o_bd->bd_info = (BackendInfo *)on;
 		if ( rc ) {
 			op->o_bd = b0;
 			return;
@@ -1200,7 +1217,7 @@ syncprov_matchops( Operation *op, opcook
 		}
 
 		/* check if current o_req_dn is in scope and matches filter */
-		if ( fc.fscope && test_filter( op, e, ss->s_op->ors_filter ) ==
+		if ( fc.fscope && test_filter( ss->s_op, e, ss->s_op->ors_filter ) ==
 			LDAP_COMPARE_TRUE ) {
 			if ( saveit ) {
 				sm = op->o_tmpalloc( sizeof(syncmatches), op->o_tmpmemctx );
@@ -1223,9 +1240,11 @@ syncprov_matchops( Operation *op, opcook
 	ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
 
 	if ( op->o_tag != LDAP_REQ_ADD && e ) {
-		op->o_bd->bd_info = (BackendInfo *)on->on_info;
-		be_entry_release_rw( op, e, 0 );
-		op->o_bd->bd_info = (BackendInfo *)on;
+		if ( !SLAP_ISOVERLAY( op->o_bd )) {
+			op->o_bd = &db;
+		}
+		overlay_entry_release_ov( op, e, 0, on );
+		op->o_bd = b0;
 	}
 	if ( freefdn ) {
 		op->o_tmpfree( fc.fdn->bv_val, op->o_tmpmemctx );
@@ -1285,12 +1304,14 @@ syncprov_op_cleanup( Operation *op, Slap
 static void
 syncprov_checkpoint( Operation *op, SlapReply *rs, slap_overinst *on )
 {
-    syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;
+	syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;
 	Modifications mod;
 	Operation opm;
 	SlapReply rsm = { 0 };
 	slap_callback cb = {0};
+	BackendDB be;
 
+	mod.sml_numvals = si->si_numcsns;
 	mod.sml_values = si->si_ctxcsn;
 	mod.sml_nvalues = NULL;
 	mod.sml_desc = slap_schema.si_ad_contextCSN;
@@ -1304,10 +1325,15 @@ syncprov_checkpoint( Operation *op, Slap
 	opm.o_callback = &cb;
 	opm.orm_modlist = &mod;
 	opm.orm_no_opattrs = 1;
-	opm.o_req_dn = op->o_bd->be_suffix[0];
-	opm.o_req_ndn = op->o_bd->be_nsuffix[0];
+	if ( SLAP_GLUE_SUBORDINATE( op->o_bd )) {
+		be = *on->on_info->oi_origdb;
+		opm.o_bd = &be;
+	}
+	opm.o_req_dn = opm.o_bd->be_suffix[0];
+	opm.o_req_ndn = opm.o_bd->be_nsuffix[0];
 	opm.o_bd->bd_info = on->on_info->oi_orig;
 	opm.o_managedsait = SLAP_CONTROL_NONCRITICAL;
+	opm.o_no_schema_check = 1;
 	opm.o_bd->be_modify( &opm, &rsm );
 	if ( mod.sml_next != NULL ) {
 		slap_mods_free( mod.sml_next, 1 );
@@ -1481,11 +1507,7 @@ syncprov_playlog( Operation *op, SlapRep
 		SlapReply frs = { REP_RESULT };
 		int rc;
 		Filter mf, af;
-#ifdef LDAP_COMP_MATCH
-		AttributeAssertion eq = { NULL, BER_BVNULL, NULL };
-#else
-		AttributeAssertion eq;
-#endif
+		AttributeAssertion eq = ATTRIBUTEASSERTION_INIT;
 		slap_callback cb = {0};
 
 		fop = *op;
@@ -1509,7 +1531,10 @@ syncprov_playlog( Operation *op, SlapRep
 		fop.ors_filter = &af;
 
 		cb.sc_response = playlog_cb;
-		fop.o_bd->bd_info = on->on_info->oi_orig;
+		if ( on->on_next )
+			fop.o_bd->bd_info = (BackendInfo *)on->on_next;
+		else
+			fop.o_bd->bd_info = on->on_info->oi_orig;
 
 		for ( i=ndel; i<num; i++ ) {
 			if ( uuids[i].bv_len == 0 ) continue;
@@ -1532,6 +1557,9 @@ syncprov_playlog( Operation *op, SlapRep
 
 		slap_compose_sync_cookie( op, &cookie, delcsn, srs->sr_state.rid,
 			srs->sr_state.sid );
+
+		Debug( LDAP_DEBUG_SYNC, "syncprov_playlog: cookie=%s\n", cookie.bv_val, 0, 0 );
+
 		uuids[ndel].bv_val = NULL;
 		syncprov_sendinfo( op, rs, LDAP_TAG_SYNC_ID_SET, &cookie, 0, uuids, 1 );
 		op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
@@ -1551,11 +1579,11 @@ syncprov_op_response( Operation *op, Sla
 	{
 		struct berval maxcsn = BER_BVNULL;
 		char cbuf[LDAP_LUTIL_CSNSTR_BUFSIZE];
-		int do_check = 0;
+		int do_check = 0, have_psearches;
 
 		/* Update our context CSN */
 		cbuf[0] = '\0';
-		ldap_pvt_thread_mutex_lock( &si->si_csn_mutex );
+		ldap_pvt_thread_rdwr_wlock( &si->si_csn_rwlock );
 		slap_get_commit_csn( op, &maxcsn );
 		if ( !BER_BVISNULL( &maxcsn ) ) {
 			int i, sid;
@@ -1582,7 +1610,7 @@ syncprov_op_response( Operation *op, Sla
 		/* Don't do any processing for consumer contextCSN updates */
 		if ( SLAP_SYNC_SHADOW( op->o_bd ) && 
 			op->o_msgid == SLAP_SYNC_UPDATE_MSGID ) {
-			ldap_pvt_thread_mutex_unlock( &si->si_csn_mutex );
+			ldap_pvt_thread_rdwr_wunlock( &si->si_csn_rwlock );
 			return SLAP_CB_CONTINUE;
 		}
 
@@ -1594,21 +1622,30 @@ syncprov_op_response( Operation *op, Sla
 			}
 			if ( si->si_chktime &&
 				(op->o_time - si->si_chklast >= si->si_chktime )) {
-				do_check = 1;
-				si->si_chklast = op->o_time;
+				if ( si->si_chklast ) {
+					do_check = 1;
+					si->si_chklast = op->o_time;
+				} else {
+					si->si_chklast = 1;
+				}
 			}
 		}
-		ldap_pvt_thread_mutex_unlock( &si->si_csn_mutex );
-
-		opc->sctxcsn.bv_len = maxcsn.bv_len;
-		opc->sctxcsn.bv_val = cbuf;
+		ldap_pvt_thread_rdwr_wunlock( &si->si_csn_rwlock );
 
 		if ( do_check ) {
+			ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
 			syncprov_checkpoint( op, rs, on );
+			ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
 		}
 
+		opc->sctxcsn.bv_len = maxcsn.bv_len;
+		opc->sctxcsn.bv_val = cbuf;
+
 		/* Handle any persistent searches */
-		if ( si->si_ops ) {
+		ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
+		have_psearches = ( si->si_ops != NULL );
+		ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
+		if ( have_psearches ) {
 			switch(op->o_tag) {
 			case LDAP_REQ_ADD:
 			case LDAP_REQ_MODIFY:
@@ -1661,7 +1698,7 @@ syncprov_op_compare( Operation *op, Slap
 
 		a.a_desc = slap_schema.si_ad_contextCSN;
 
-		ldap_pvt_thread_mutex_lock( &si->si_csn_mutex );
+		ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
 
 		a.a_vals = si->si_ctxcsn;
 		a.a_nvals = a.a_vals;
@@ -1683,17 +1720,17 @@ syncprov_op_compare( Operation *op, Slap
 
 		rs->sr_err = LDAP_COMPARE_FALSE;
 
-		if ( value_find_ex( op->oq_compare.rs_ava->aa_desc,
+		if ( attr_valfind( &a,
 			SLAP_MR_ATTRIBUTE_VALUE_NORMALIZED_MATCH |
 				SLAP_MR_ASSERTED_VALUE_NORMALIZED_MATCH,
-				a.a_nvals, &op->oq_compare.rs_ava->aa_value, op->o_tmpmemctx ) == 0 )
+				&op->oq_compare.rs_ava->aa_value, NULL, op->o_tmpmemctx ) == 0 )
 		{
 			rs->sr_err = LDAP_COMPARE_TRUE;
 		}
 
 return_results:;
 
-		ldap_pvt_thread_mutex_unlock( &si->si_csn_mutex );
+		ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
 
 		send_ldap_result( op, rs );
 
@@ -1711,12 +1748,19 @@ syncprov_op_mod( Operation *op, SlapRepl
 {
 	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
 	syncprov_info_t		*si = on->on_bi.bi_private;
+	slap_callback *cb;
+	opcookie *opc;
+	int have_psearches, cbsize;
+
+	ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
+	have_psearches = ( si->si_ops != NULL );
+	ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
 
-	slap_callback *cb = op->o_tmpcalloc(1, sizeof(slap_callback)+
-		sizeof(opcookie) +
-		(si->si_ops ? sizeof(modinst) : 0 ),
-		op->o_tmpmemctx);
-	opcookie *opc = (opcookie *)(cb+1);
+	cbsize = sizeof(slap_callback) + sizeof(opcookie) +
+		(have_psearches ? sizeof(modinst) : 0 );
+
+	cb = op->o_tmpcalloc(1, cbsize, op->o_tmpmemctx);
+	opc = (opcookie *)(cb+1);
 	opc->son = on;
 	cb->sc_response = syncprov_op_response;
 	cb->sc_cleanup = syncprov_op_cleanup;
@@ -1727,7 +1771,7 @@ syncprov_op_mod( Operation *op, SlapRepl
 	/* If there are active persistent searches, lock this operation.
 	 * See seqmod.c for the locking logic on its own.
 	 */
-	if ( si->si_ops ) {
+	if ( have_psearches ) {
 		modtarget *mt, mtdummy;
 		modinst *mi;
 
@@ -1746,7 +1790,13 @@ syncprov_op_mod( Operation *op, SlapRepl
 			/* wait for this op to get to head of list */
 			while ( mt->mt_mods != mi ) {
 				ldap_pvt_thread_mutex_unlock( &mt->mt_mutex );
-				ldap_pvt_thread_yield();
+				/* FIXME: if dynamic config can delete overlays or
+				 * databases we'll have to check for cleanup here.
+				 * Currently it's not an issue because there are
+				 * no dynamic config deletes...
+				 */
+				if ( !ldap_pvt_thread_pool_pausecheck( &connection_pool ))
+					ldap_pvt_thread_yield();
 				ldap_pvt_thread_mutex_lock( &mt->mt_mutex );
 
 				/* clean up if the caller is giving up */
@@ -1774,7 +1824,7 @@ syncprov_op_mod( Operation *op, SlapRepl
 		}
 	}
 
-	if (( si->si_ops || si->si_logs ) && op->o_tag != LDAP_REQ_ADD )
+	if (( have_psearches || si->si_logs ) && op->o_tag != LDAP_REQ_ADD )
 		syncprov_matchops( op, opc, 1 );
 
 	return SLAP_CB_CONTINUE;
@@ -1795,7 +1845,9 @@ typedef struct searchstate {
 	BerVarray ss_ctxcsn;
 	int *ss_sids;
 	int ss_numcsns;
-	int ss_present;
+#define	SS_PRESENT	0x01
+#define	SS_CHANGED	0x02
+	int ss_flags;
 } searchstate;
 
 static int
@@ -1809,9 +1861,18 @@ syncprov_search_cleanup( Operation *op,
 	return 0;
 }
 
+typedef struct SyncOperationBuffer {
+	Operation		sob_op;
+	Opheader		sob_hdr;
+	OpExtra			sob_oe;
+	AttributeName	sob_extra;	/* not always present */
+	/* Further data allocated here */
+} SyncOperationBuffer;
+
 static void
 syncprov_detach_op( Operation *op, syncops *so, slap_overinst *on )
 {
+	SyncOperationBuffer *sopbuf2;
 	Operation *op2;
 	int i, alen = 0;
 	size_t size;
@@ -1823,14 +1884,16 @@ syncprov_detach_op( Operation *op, synco
 		alen += op->ors_attrs[i].an_name.bv_len + 1;
 	}
 	/* Make a new copy of the operation */
-	size = sizeof(Operation) + sizeof(Opheader) +
+	size = offsetof( SyncOperationBuffer, sob_extra ) +
 		(i ? ( (i+1) * sizeof(AttributeName) + alen) : 0) +
 		op->o_req_dn.bv_len + 1 +
 		op->o_req_ndn.bv_len + 1 +
 		op->o_ndn.bv_len + 1 +
 		so->s_filterstr.bv_len + 1;
-	op2 = (Operation *)ch_calloc( 1, size );
-	op2->o_hdr = (Opheader *)(op2+1);
+	sopbuf2 = ch_calloc( 1, size );
+	op2 = &sopbuf2->sob_op;
+	op2->o_hdr = &sopbuf2->sob_hdr;
+	LDAP_SLIST_FIRST(&op2->o_extra) = &sopbuf2->sob_oe;
 
 	/* Copy the fields we care about explicitly, leave the rest alone */
 	*op2->o_hdr = *op->o_hdr;
@@ -1838,20 +1901,21 @@ syncprov_detach_op( Operation *op, synco
 	op2->o_time = op->o_time;
 	op2->o_bd = on->on_info->oi_origdb;
 	op2->o_request = op->o_request;
-	op2->o_private = on;
+	LDAP_SLIST_FIRST(&op2->o_extra)->oe_key = on;
+	LDAP_SLIST_NEXT(LDAP_SLIST_FIRST(&op2->o_extra), oe_next) = NULL;
 
+	ptr = (char *) sopbuf2 + offsetof( SyncOperationBuffer, sob_extra );
 	if ( i ) {
-		op2->ors_attrs = (AttributeName *)(op2->o_hdr + 1);
-		ptr = (char *)(op2->ors_attrs+i+1);
+		op2->ors_attrs = (AttributeName *) ptr;
+		ptr = (char *) &op2->ors_attrs[i+1];
 		for (i=0; !BER_BVISNULL( &op->ors_attrs[i].an_name ); i++) {
 			op2->ors_attrs[i] = op->ors_attrs[i];
 			op2->ors_attrs[i].an_name.bv_val = ptr;
 			ptr = lutil_strcopy( ptr, op->ors_attrs[i].an_name.bv_val ) + 1;
 		}
 		BER_BVZERO( &op2->ors_attrs[i].an_name );
-	} else {
-		ptr = (char *)(op2->o_hdr + 1);
 	}
+
 	op2->o_authz = op->o_authz;
 	op2->o_ndn.bv_val = ptr;
 	ptr = lutil_strcopy(ptr, op->o_ndn.bv_val) + 1;
@@ -1889,12 +1953,10 @@ syncprov_detach_op( Operation *op, synco
 	op2->o_do_not_cache = 1;
 
 	/* Add op2 to conn so abandon will find us */
-	ldap_pvt_thread_mutex_lock( &op->o_conn->c_mutex );
 	op->o_conn->c_n_ops_executing++;
 	op->o_conn->c_n_ops_completed--;
 	LDAP_STAILQ_INSERT_TAIL( &op->o_conn->c_ops, op2, o_next );
 	so->s_flags |= PS_IS_DETACHED;
-	ldap_pvt_thread_mutex_unlock( &op->o_conn->c_mutex );
 
 	/* Prevent anyone else from trying to send a result for this op */
 	op->o_abandon = 1;
@@ -1928,22 +1990,26 @@ syncprov_search_response( Operation *op,
 			sid = slap_parse_csn_sid( &a->a_nvals[0] );
 
 			/* Don't send changed entries back to the originator */
-			if ( sid == srs->sr_state.sid ) {
+			if ( sid == srs->sr_state.sid && srs->sr_state.numcsns ) {
 				Debug( LDAP_DEBUG_SYNC,
 					"Entry %s changed by peer, ignored\n",
 					rs->sr_entry->e_name.bv_val, 0, 0 );
 				return LDAP_SUCCESS;
 			}
-			/* Make sure entry is less than the snapshot'd contextCSN */
-			for ( i=0; i<ss->ss_numcsns; i++ ) {
-				if ( sid == ss->ss_sids[i] && ber_bvcmp( &a->a_nvals[0],
-					&ss->ss_ctxcsn[i] ) > 0 ) {
-					Debug( LDAP_DEBUG_SYNC,
-						"Entry %s CSN %s greater than snapshot %s\n",
-						rs->sr_entry->e_name.bv_val,
-						a->a_nvals[0].bv_val,
-						ss->ss_ctxcsn[i].bv_val );
-					return LDAP_SUCCESS;
+
+			/* If not a persistent search */
+			if ( !ss->ss_so ) {
+				/* Make sure entry is less than the snapshot'd contextCSN */
+				for ( i=0; i<ss->ss_numcsns; i++ ) {
+					if ( sid == ss->ss_sids[i] && ber_bvcmp( &a->a_nvals[0],
+						&ss->ss_ctxcsn[i] ) > 0 ) {
+						Debug( LDAP_DEBUG_SYNC,
+							"Entry %s CSN %s greater than snapshot %s\n",
+							rs->sr_entry->e_name.bv_val,
+							a->a_nvals[0].bv_val,
+							ss->ss_ctxcsn[i].bv_val );
+						return LDAP_SUCCESS;
+					}
 				}
 			}
 
@@ -1971,36 +2037,56 @@ syncprov_search_response( Operation *op,
 	} else if ( rs->sr_type == REP_RESULT && rs->sr_err == LDAP_SUCCESS ) {
 		struct berval cookie;
 
-		slap_compose_sync_cookie( op, &cookie, ss->ss_ctxcsn,
-			srs->sr_state.rid, srs->sr_state.sid );
+		if ( ss->ss_flags & SS_CHANGED ) {
+			slap_compose_sync_cookie( op, &cookie, ss->ss_ctxcsn,
+				srs->sr_state.rid, srs->sr_state.sid );
+
+			Debug( LDAP_DEBUG_SYNC, "syncprov_search_response: cookie=%s\n", cookie.bv_val, 0, 0 );
+		}
 
-		/* Is this a regular refresh? */
+		/* Is this a regular refresh?
+		 * Note: refresh never gets here if there were no changes
+		 */
 		if ( !ss->ss_so ) {
 			rs->sr_ctrls = op->o_tmpalloc( sizeof(LDAPControl *)*2,
 				op->o_tmpmemctx );
 			rs->sr_ctrls[1] = NULL;
 			rs->sr_err = syncprov_done_ctrl( op, rs, rs->sr_ctrls,
-				0, 1, &cookie, ss->ss_present ?  LDAP_SYNC_REFRESH_PRESENTS :
+				0, 1, &cookie, ( ss->ss_flags & SS_PRESENT ) ?  LDAP_SYNC_REFRESH_PRESENTS :
 					LDAP_SYNC_REFRESH_DELETES );
 			op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
 		} else {
 		/* It's RefreshAndPersist, transition to Persist phase */
-			syncprov_sendinfo( op, rs, ss->ss_present ?
+			syncprov_sendinfo( op, rs, ( ss->ss_flags & SS_PRESENT ) ?
 	 			LDAP_TAG_SYNC_REFRESH_PRESENT : LDAP_TAG_SYNC_REFRESH_DELETE,
-				&cookie, 1, NULL, 0 );
-			op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
+				( ss->ss_flags & SS_CHANGED ) ? &cookie : NULL,
+				1, NULL, 0 );
+			if ( ss->ss_flags & SS_CHANGED )
+				op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
 
 			/* Detach this Op from frontend control */
 			ldap_pvt_thread_mutex_lock( &ss->ss_so->s_mutex );
+			ldap_pvt_thread_mutex_lock( &op->o_conn->c_mutex );
 
-			/* Turn off the refreshing flag */
-			ss->ss_so->s_flags ^= PS_IS_REFRESHING;
+			/* But not if this connection was closed along the way */
+			if ( op->o_abandon ) {
+				ldap_pvt_thread_mutex_unlock( &op->o_conn->c_mutex );
+				ldap_pvt_thread_mutex_unlock( &ss->ss_so->s_mutex );
+				syncprov_free_syncop( ss->ss_so );
+				return SLAPD_ABANDON;
 
-			syncprov_detach_op( op, ss->ss_so, on );
+			} else {
+				/* Turn off the refreshing flag */
+				ss->ss_so->s_flags ^= PS_IS_REFRESHING;
 
-			/* If there are queued responses, fire them off */
-			if ( ss->ss_so->s_res )
-				syncprov_qstart( ss->ss_so );
+				syncprov_detach_op( op, ss->ss_so, on );
+
+				ldap_pvt_thread_mutex_unlock( &op->o_conn->c_mutex );
+
+				/* If there are queued responses, fire them off */
+				if ( ss->ss_so->s_res )
+					syncprov_qstart( ss->ss_so );
+			}
 			ldap_pvt_thread_mutex_unlock( &ss->ss_so->s_mutex );
 
 			return LDAP_SUCCESS;
@@ -2016,7 +2102,7 @@ syncprov_op_search( Operation *op, SlapR
 	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
 	syncprov_info_t		*si = (syncprov_info_t *)on->on_bi.bi_private;
 	slap_callback	*cb;
-	int gotstate = 0, nochange = 0, do_present;
+	int gotstate = 0, changed = 0, do_present = 0;
 	syncops *sop = NULL;
 	searchstate *ss;
 	sync_control *srs;
@@ -2031,8 +2117,6 @@ syncprov_op_search( Operation *op, SlapR
 		return rs->sr_err;
 	}
 
-	do_present = si->si_nopres ? 0 : 1;
-
 	srs = op->o_controls[slap_cids.sc_LDAPsync];
 	op->o_managedsait = SLAP_CONTROL_NONCRITICAL;
 
@@ -2066,7 +2150,7 @@ syncprov_op_search( Operation *op, SlapR
 		*sop = so;
 		ldap_pvt_thread_mutex_init( &sop->s_mutex );
 		sop->s_rid = srs->sr_state.rid;
-		sop->s_rid = srs->sr_state.sid;
+		sop->s_sid = srs->sr_state.sid;
 		sop->s_inuse = 1;
 
 		ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
@@ -2076,7 +2160,7 @@ syncprov_op_search( Operation *op, SlapR
 	}
 
 	/* snapshot the ctxcsn */
-	ldap_pvt_thread_mutex_lock( &si->si_csn_mutex );
+	ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
 	numcsns = si->si_numcsns;
 	if ( numcsns ) {
 		ber_bvarray_dup_x( &ctxcsn, si->si_ctxcsn, op->o_tmpmemctx );
@@ -2087,7 +2171,7 @@ syncprov_op_search( Operation *op, SlapR
 		ctxcsn = NULL;
 		sids = NULL;
 	}
-	ldap_pvt_thread_mutex_unlock( &si->si_csn_mutex );
+	ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
 	
 	/* If we have a cookie, handle the PRESENT lookups */
 	if ( srs->sr_state.ctxcsn ) {
@@ -2100,6 +2184,9 @@ syncprov_op_search( Operation *op, SlapR
 		if ( !numcsns )
 			goto no_change;
 
+		if ( !si->si_nopres )
+			do_present = SS_PRESENT;
+
 		/* If there are SIDs we don't recognize in the cookie, drop them */
 		for (i=0; i<srs->sr_state.numcsns; ) {
 			for (j=0; j<numcsns; j++) {
@@ -2130,21 +2217,21 @@ syncprov_op_search( Operation *op, SlapR
 
 		/* If nothing has changed, shortcut it */
 		if ( srs->sr_state.numcsns == numcsns ) {
-			int i, j, changed = 0;
+			int i, j;
 			for ( i=0; i<srs->sr_state.numcsns; i++ ) {
 				for ( j=0; j<numcsns; j++ ) {
 					if ( srs->sr_state.sids[i] != sids[j] )
 						continue;
 					if ( !bvmatch( &srs->sr_state.ctxcsn[i], &ctxcsn[j] ))
-						changed = 1;
+						changed = SS_CHANGED;
 					break;
 				}
 				if ( changed )
 					break;
 			}
 			if ( !changed ) {
-no_change:		nochange = 1;
-				if ( !(op->o_sync_mode & SLAP_SYNC_PERSIST) ) {
+				do_present = 0;
+no_change:		if ( !(op->o_sync_mode & SLAP_SYNC_PERSIST) ) {
 					LDAPControl	*ctrls[2];
 
 					ctrls[0] = NULL;
@@ -2180,6 +2267,10 @@ no_change:		nochange = 1;
 			/* No, so a reload is required */
 			/* the 2.2 consumer doesn't send this hint */
 			if ( si->si_usehint && srs->sr_rhint == 0 ) {
+				if ( ctxcsn )
+					ber_bvarray_free_x( ctxcsn, op->o_tmpmemctx );
+				if ( sids )
+					op->o_tmpfree( sids, op->o_tmpmemctx );
 				send_ldap_error( op, rs, LDAP_SYNC_REFRESH_REQUIRED, "sync cookie is stale" );
 				return rs->sr_err;
 			}
@@ -2188,10 +2279,17 @@ no_change:		nochange = 1;
 			/* If changed and doing Present lookup, send Present UUIDs */
 			if ( do_present && syncprov_findcsn( op, FIND_PRESENT ) !=
 				LDAP_SUCCESS ) {
+				if ( ctxcsn )
+					ber_bvarray_free_x( ctxcsn, op->o_tmpmemctx );
+				if ( sids )
+					op->o_tmpfree( sids, op->o_tmpmemctx );
 				send_ldap_result( op, rs );
 				return rs->sr_err;
 			}
 		}
+	} else {
+		/* No consumer state, assume something has changed */
+		changed = SS_CHANGED;
 	}
 
 shortcut:
@@ -2203,7 +2301,7 @@ shortcut:
 	}
 
 	/* If something changed, find the changes */
-	if ( gotstate && !nochange ) {
+	if ( gotstate && changed ) {
 		Filter *fand, *fava;
 
 		fand = op->o_tmpalloc( sizeof(Filter), op->o_tmpmemctx );
@@ -2230,7 +2328,7 @@ shortcut:
 	ss = (searchstate *)(cb+1);
 	ss->ss_on = on;
 	ss->ss_so = sop;
-	ss->ss_present = do_present;
+	ss->ss_flags = do_present | changed;
 	ss->ss_ctxcsn = ctxcsn;
 	ss->ss_numcsns = numcsns;
 	ss->ss_sids = sids;
@@ -2244,7 +2342,7 @@ shortcut:
 	 * the refresh phase, just invoke the response callback to transition
 	 * us into persist phase
 	 */
-	if ( nochange ) {
+	if ( !changed ) {
 		rs->sr_err = LDAP_SUCCESS;
 		rs->sr_nentries = 0;
 		send_ldap_result( op, rs );
@@ -2261,6 +2359,12 @@ syncprov_operational(
 	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
 	syncprov_info_t		*si = (syncprov_info_t *)on->on_bi.bi_private;
 
+	/* This prevents generating unnecessarily; frontend will strip
+	 * any statically stored copy.
+	 */
+	if ( op->o_sync != SLAP_CONTROL_NONE )
+		return SLAP_CB_CONTINUE;
+
 	if ( rs->sr_entry &&
 		dn_match( &rs->sr_entry->e_nname, op->o_bd->be_nsuffix )) {
 
@@ -2273,7 +2377,7 @@ syncprov_operational(
 					break;
 			}
 
-			ldap_pvt_thread_mutex_lock( &si->si_csn_mutex );
+			ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
 			if ( si->si_ctxcsn ) {
 				if ( !a ) {
 					for ( ap = &rs->sr_operational_attrs; *ap;
@@ -2291,12 +2395,17 @@ syncprov_operational(
 						a = attr_find( rs->sr_entry->e_attrs,
 							slap_schema.si_ad_contextCSN );
 					}
-					free( a->a_vals );
+					if ( a->a_nvals != a->a_vals ) {
+						ber_bvarray_free( a->a_nvals );
+					}
+					a->a_nvals = NULL;
+					ber_bvarray_free( a->a_vals );
+					a->a_vals = NULL;
+					a->a_numvals = 0;
 				}
-				ber_bvarray_dup_x( &a->a_vals, si->si_ctxcsn, NULL );
-				a->a_nvals = a->a_vals;
+				attr_valadd( a, si->si_ctxcsn, si->si_ctxcsn, si->si_numcsns );
 			}
-			ldap_pvt_thread_mutex_unlock( &si->si_csn_mutex );
+			ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
 		}
 	}
 	return SLAP_CB_CONTINUE;
@@ -2353,10 +2462,14 @@ sp_cf_gen(ConfigArgs *c)
 		case SP_CHKPT:
 			if ( si->si_chkops || si->si_chktime ) {
 				struct berval bv;
-				bv.bv_len = sprintf( c->msg, "%d %d",
-					si->si_chkops, si->si_chktime );
-				bv.bv_val = c->msg;
-				value_add_one( &c->rvalue_vals, &bv );
+				bv.bv_len = snprintf( c->cr_msg, sizeof( c->cr_msg ),
+					"%d %d", si->si_chkops, si->si_chktime );
+				if ( bv.bv_len < 0 || bv.bv_len >= sizeof( c->cr_msg ) ) {
+					rc = 1;
+				} else {
+					bv.bv_val = c->cr_msg;
+					value_add_one( &c->rvalue_vals, &bv );
+				}
 			} else {
 				rc = 1;
 			}
@@ -2414,31 +2527,31 @@ sp_cf_gen(ConfigArgs *c)
 	switch ( c->type ) {
 	case SP_CHKPT:
 		if ( lutil_atoi( &si->si_chkops, c->argv[1] ) != 0 ) {
-			snprintf( c->msg, sizeof( c->msg ), "%s unable to parse checkpoint ops # \"%s\"",
+			snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s unable to parse checkpoint ops # \"%s\"",
 				c->argv[0], c->argv[1] );
 			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
-				"%s: %s\n", c->log, c->msg, 0 );
+				"%s: %s\n", c->log, c->cr_msg, 0 );
 			return ARG_BAD_CONF;
 		}
 		if ( si->si_chkops <= 0 ) {
-			snprintf( c->msg, sizeof( c->msg ), "%s invalid checkpoint ops # \"%d\"",
+			snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s invalid checkpoint ops # \"%d\"",
 				c->argv[0], si->si_chkops );
 			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
-				"%s: %s\n", c->log, c->msg, 0 );
+				"%s: %s\n", c->log, c->cr_msg, 0 );
 			return ARG_BAD_CONF;
 		}
 		if ( lutil_atoi( &si->si_chktime, c->argv[2] ) != 0 ) {
-			snprintf( c->msg, sizeof( c->msg ), "%s unable to parse checkpoint time \"%s\"",
+			snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s unable to parse checkpoint time \"%s\"",
 				c->argv[0], c->argv[1] );
 			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
-				"%s: %s\n", c->log, c->msg, 0 );
+				"%s: %s\n", c->log, c->cr_msg, 0 );
 			return ARG_BAD_CONF;
 		}
 		if ( si->si_chktime <= 0 ) {
-			snprintf( c->msg, sizeof( c->msg ), "%s invalid checkpoint time \"%d\"",
+			snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s invalid checkpoint time \"%d\"",
 				c->argv[0], si->si_chkops );
 			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
-				"%s: %s\n", c->log, c->msg, 0 );
+				"%s: %s\n", c->log, c->cr_msg, 0 );
 			return ARG_BAD_CONF;
 		}
 		si->si_chktime *= 60;
@@ -2448,10 +2561,10 @@ sp_cf_gen(ConfigArgs *c)
 		int size = c->value_int;
 
 		if ( size < 0 ) {
-			snprintf( c->msg, sizeof( c->msg ), "%s size %d is negative",
+			snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s size %d is negative",
 				c->argv[0], size );
 			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
-				"%s: %s\n", c->log, c->msg, 0 );
+				"%s: %s\n", c->log, c->cr_msg, 0 );
 			return ARG_BAD_CONF;
 		}
 		sl = si->si_logs;
@@ -2495,16 +2608,17 @@ syncprov_db_otask(
  */
 static int
 syncprov_db_open(
-    BackendDB *be
+	BackendDB *be,
+	ConfigReply *cr
 )
 {
 	slap_overinst   *on = (slap_overinst *) be->bd_info;
 	syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;
 
 	Connection conn = { 0 };
-	OperationBuffer opbuf = { 0 };
-	Operation *op = (Operation *) &opbuf;
-	Entry *e;
+	OperationBuffer opbuf;
+	Operation *op;
+	Entry *e = NULL;
 	Attribute *a;
 	int rc;
 	void *thrctx = NULL;
@@ -2525,29 +2639,26 @@ syncprov_db_open(
 	}
 
 	thrctx = ldap_pvt_thread_pool_context();
-	connection_fake_init( &conn, op, thrctx );
+	connection_fake_init( &conn, &opbuf, thrctx );
+	op = &opbuf.ob_op;
 	op->o_bd = be;
 	op->o_dn = be->be_rootdn;
 	op->o_ndn = be->be_rootndn;
 
-	op->o_bd->bd_info = on->on_info->oi_orig;
-	rc = be_entry_get_rw( op, be->be_nsuffix, NULL,
-		slap_schema.si_ad_contextCSN, 0, &e );
+	rc = overlay_entry_get_ov( op, be->be_nsuffix, NULL,
+		slap_schema.si_ad_contextCSN, 0, &e, on );
 
 	if ( e ) {
 		ldap_pvt_thread_t tid;
 
 		a = attr_find( e->e_attrs, slap_schema.si_ad_contextCSN );
 		if ( a ) {
-			int i;
 			ber_bvarray_dup_x( &si->si_ctxcsn, a->a_vals, NULL );
-			for ( i=0; !BER_BVISEMPTY( &a->a_vals[i] ); i++ );
-			si->si_numcsns = i;
-			si->si_sids = slap_parse_csn_sids( si->si_ctxcsn, i );
+			si->si_numcsns = a->a_numvals;
+			si->si_sids = slap_parse_csn_sids( si->si_ctxcsn, a->a_numvals, NULL );
 		}
-		be_entry_release_rw( op, e, 0 );
+		overlay_entry_release_ov( op, e, 0, on );
 		if ( si->si_ctxcsn ) {
-			op->o_bd->bd_info = (BackendInfo *)on;
 			op->o_req_dn = be->be_suffix[0];
 			op->o_req_ndn = be->be_nsuffix[0];
 			op->ors_scope = LDAP_SCOPE_SUBTREE;
@@ -2589,7 +2700,8 @@ out:
  */
 static int
 syncprov_db_close(
-    BackendDB *be
+	BackendDB *be,
+	ConfigReply *cr
 )
 {
     slap_overinst   *on = (slap_overinst *) be->bd_info;
@@ -2599,14 +2711,15 @@ syncprov_db_close(
 		return 0;
 	}
 	if ( si->si_numops ) {
-		Connection conn;
+		Connection conn = {0};
 		OperationBuffer opbuf;
-		Operation *op = (Operation *) &opbuf;
+		Operation *op;
 		SlapReply rs = {REP_RESULT};
 		void *thrctx;
 
 		thrctx = ldap_pvt_thread_pool_context();
-		connection_fake_init( &conn, op, thrctx );
+		connection_fake_init( &conn, &opbuf, thrctx );
+		op = &opbuf.ob_op;
 		op->o_bd = be;
 		op->o_dn = be->be_rootdn;
 		op->o_ndn = be->be_rootndn;
@@ -2618,7 +2731,8 @@ syncprov_db_close(
 
 static int
 syncprov_db_init(
-	BackendDB *be
+	BackendDB *be,
+	ConfigReply *cr
 )
 {
 	slap_overinst	*on = (slap_overinst *)be->bd_info;
@@ -2633,7 +2747,7 @@ syncprov_db_init(
 
 	si = ch_calloc(1, sizeof(syncprov_info_t));
 	on->on_bi.bi_private = si;
-	ldap_pvt_thread_mutex_init( &si->si_csn_mutex );
+	ldap_pvt_thread_rdwr_init( &si->si_csn_rwlock );
 	ldap_pvt_thread_mutex_init( &si->si_ops_mutex );
 	ldap_pvt_thread_mutex_init( &si->si_mods_mutex );
 
@@ -2650,7 +2764,8 @@ syncprov_db_init(
 
 static int
 syncprov_db_destroy(
-	BackendDB *be
+	BackendDB *be,
+	ConfigReply *cr
 )
 {
 	slap_overinst	*on = (slap_overinst *)be->bd_info;
@@ -2668,9 +2783,13 @@ syncprov_db_destroy(
 				
 			ch_free( si->si_logs );
 		}
+		if ( si->si_ctxcsn )
+			ber_bvarray_free( si->si_ctxcsn );
+		if ( si->si_sids )
+			ch_free( si->si_sids );
 		ldap_pvt_thread_mutex_destroy( &si->si_mods_mutex );
 		ldap_pvt_thread_mutex_destroy( &si->si_ops_mutex );
-		ldap_pvt_thread_mutex_destroy( &si->si_csn_mutex );
+		ldap_pvt_thread_rdwr_destroy( &si->si_csn_rwlock );
 		ch_free( si );
 	}
 
@@ -2701,8 +2820,13 @@ static int syncprov_parseCtrl (
 		return LDAP_PROTOCOL_ERROR;
 	}
 
+	if ( BER_BVISNULL( &ctrl->ldctl_value ) ) {
+		rs->sr_text = "Sync control value is absent";
+		return LDAP_PROTOCOL_ERROR;
+	}
+
 	if ( BER_BVISEMPTY( &ctrl->ldctl_value ) ) {
-		rs->sr_text = "Sync control value is empty (or absent)";
+		rs->sr_text = "Sync control value is empty";
 		return LDAP_PROTOCOL_ERROR;
 	}
 
@@ -2760,10 +2884,14 @@ static int syncprov_parseCtrl (
 	sr->sr_rhint = rhint;
 	if (!BER_BVISNULL(&cookie)) {
 		ber_dupbv_x( &sr->sr_state.octet_str, &cookie, op->o_tmpmemctx );
-		slap_parse_sync_cookie( &sr->sr_state, op->o_tmpmemctx );
-		if ( sr->sr_state.rid == -1 ) {
-			rs->sr_text = "Sync control : cookie parsing error";
-			return LDAP_PROTOCOL_ERROR;
+		/* If parse fails, pretend no cookie was sent */
+		if ( slap_parse_sync_cookie( &sr->sr_state, op->o_tmpmemctx ) ||
+			sr->sr_state.rid == -1 ) {
+			if ( sr->sr_state.ctxcsn ) {
+				ber_bvarray_free_x( sr->sr_state.ctxcsn, op->o_tmpmemctx );
+				sr->sr_state.ctxcsn = NULL;
+			}
+			sr->sr_state.numcsns = 0;
 		}
 	}