code: plan9front

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devip: use better hashipa() macro, use RWlock for arp cache

--- a/sys/src/9/ip/arp.c

+++ b/sys/src/9/ip/arp.c

@@ -33,7 +33,7 @@

  */

 struct Arp

 {

-	QLock;

+	RWlock;

 	Fs	*f;

 	Arpent	*hash[NHASH];

 	Arpent	cache[NCACHE];

@@ -45,7 +45,8 @@

 char *Ebadarp = "bad arp";

-#define haship(s) ((s)[IPaddrlen-1]%NHASH)

+/* quick hash for ip addresses */

+#define hashipa(a) (((a)[IPaddrlen-2] + (a)[IPaddrlen-1])%NHASH)

 static void 	rxmitproc(void*);

@@ -95,7 +96,7 @@

 	Block *bp;

 	/* take out of current chain */

-	for(l = &arp->hash[haship(a->ip)]; *l != nil; l = &((*l)->hash)){

+	for(l = &arp->hash[hashipa(a->ip)]; *l != nil; l = &((*l)->hash)){

 		if(*l == a){

 			*l = a->hash;

 			break;

@@ -127,9 +128,6 @@

 	a->utime = 0;

 	a->ctime = 0;

-

-	memset(a->ip, 0, sizeof(a->ip));

-	memset(a->mac, 0, sizeof(a->mac));

 }

 /*

@@ -158,7 +156,7 @@

 	a->ifcid = ifc->ifcid;

 	/* insert into new chain */

-	l = &arp->hash[haship(ip)];

+	l = &arp->hash[hashipa(ip)];

 	a->hash = *l;

 	*l = a;

@@ -165,7 +163,18 @@

 	return a;

 }

+static Arpent*

+arplookup(Arp *arp, Ipifc *ifc, uchar *ip)

+{

+	Arpent *a;

+	for(a = arp->hash[hashipa(ip)]; a != nil; a = a->hash){

+		if(a->ifc == ifc && a->ifcid == ifc->ifcid && ipcmp(ip, a->ip) == 0)

+			return a;

+	}

+	return nil;

+}

+

 /*

  *  fill in the media address if we have it.  Otherwise return an

  *  Arpent that represents the state of the address resolution FSM

@@ -175,44 +184,39 @@

 Arpent*

 arpget(Arp *arp, Block *bp, int version, Ipifc *ifc, uchar *ip, uchar *mac)

 {

-	Arpent *a;

 	uchar v6ip[IPaddrlen];

+	Arpent *a;

 	if(version == V4){

 		v4tov6(v6ip, ip);

 		ip = v6ip;

 	}

-

-	qlock(arp);

-	for(a = arp->hash[haship(ip)]; a != nil; a = a->hash){

-		if(a->ifc == ifc && a->ifcid == ifc->ifcid && ipcmp(ip, a->ip) == 0)

-			break;

+	rlock(arp);

+	if((a = arplookup(arp, ifc, ip)) != nil && a->state == AOK){

+		memmove(mac, a->mac, ifc->m->maclen);

+		a->utime = NOW;

+		if(a->utime - a->ctime < 15*60*1000){

+			runlock(arp);

+			return nil;

+		}

 	}

-	if(a == nil){

+	runlock(arp);

+	wlock(arp);

+	if((a = arplookup(arp, ifc, ip)) == nil)

 		a = newarpent(arp, ip, ifc);

-		a->state = AWAIT;

-	}

+	a->state = AWAIT;

 	a->utime = NOW;

-	if(a->state == AWAIT){

-		if(bp != nil){

-			bp->list = nil; 

-			if(a->hold == nil)

-				a->hold = bp;

-			else

-				a->last->list = bp;

-			a->last = bp;

-		}

-		return a;		/* return with arp qlocked */

-	}

+	if(bp != nil){

+		/* needs to be a single block */

+		assert(bp->list == nil);

-	memmove(mac, a->mac, ifc->m->maclen);

-

-	/* remove old entries */

-	if(NOW - a->ctime > 15*60*1000)

-		cleanarpent(arp, a);

-

-	qunlock(arp);

-	return nil;

+		if(a->hold == nil)

+			a->hold = bp;

+		else

+			a->last->list = bp;

+		a->last = bp;

+	}

+	return a;		/* return with arp locked */

 }

 /*

@@ -226,9 +230,6 @@

 	Arpent **l;

 	Block *bp;

-	/* try to keep it around for a second more */

-	a->ctime = NOW;

-

 	/* remove all but the last message */

 	while((bp = a->hold) != nil){

 		if(bp == a->last)

@@ -237,6 +238,9 @@

 		freeblist(bp);

 	}

+	/* try to keep it around for a second more */

+	a->ctime = a->utime = NOW;

+

 	/* put on end of re-transmit / timeout chain */

 	for(l = rxmtunchain(arp, a); *l != nil; l = &(*l)->nextrxt)

 		;

@@ -245,7 +249,7 @@

 	if(l == &arp->rxmt[0] || l == &arp->rxmt[1])

 		wakeup(&arp->rxmtq);

-	qunlock(arp);

+	wunlock(arp);

 }

 /*

@@ -254,7 +258,7 @@

 void

 arprelease(Arp *arp, Arpent*)

 {

-	qunlock(arp);

+	wunlock(arp);

 }

@@ -274,11 +278,11 @@

 		rxmtunchain(arp, a);

 		a->rxtsrem = 0;

 	}

-	a->state = AOK;

-	a->ctime = a->utime = NOW;

 	bp = a->hold;

 	a->hold = a->last = nil;

-	qunlock(arp);

+	a->ctime = a->utime = NOW;

+	a->state = AOK;

+	wunlock(arp);

 	return bp;

 }

@@ -313,37 +317,29 @@

 		return -1;

 	arp = fs->arp;

-	qlock(arp);

-	for(a = arp->hash[haship(ip)]; a != nil; a = a->hash){

-		if(a->ifc != ifc || a->ifcid != ifc->ifcid)

-			continue;

-		if(ipcmp(a->ip, ip) == 0){

-			if(version == V4)

-				ip += IPv4off;

-			bp = arpresolve(arp, a, ifc->m, mac);	/* unlocks arp */

-			for(; bp != nil; bp = next){

-				next = bp->list;

-				bp->list = nil;

-				if(waserror()){

-					freeblistchain(next);

-					break;

-				}

-				ipifcoput(ifc, bp, version, ip);

-				poperror();

-			}

-			return 1;

-		}

-	}

-	if(refresh == 0){

+	wlock(arp);

+	if((a = arplookup(arp, ifc, ip)) == nil){

+		if(refresh){

+			wunlock(arp);

+			return 0;

+		}

 		a = newarpent(arp, ip, ifc);

-		a->state = AOK;

-		a->ctime = a->utime = NOW;

-		memmove(a->mac, mac, n);

 	}

-	qunlock(arp);

-

-	return refresh == 0;

+	if(version == V4)

+		ip += IPv4off;

+	bp = arpresolve(arp, a, ifc->m, mac);	/* unlocks arp */

+	for(; bp != nil; bp = next){

+		next = bp->list;

+		bp->list = nil;

+		if(waserror()){

+			freeblistchain(next);

+			break;

+		}

+		ipifcoput(ifc, bp, version, ip);

+		poperror();

+	}

+	return 1;

 }

 int

@@ -370,10 +366,8 @@

 	n = getfields(buf, f, nelem(f), 1, " ");

 	if(strcmp(f[0], "flush") == 0){

-		qlock(arp);

+		wlock(arp);

 		for(a = arp->cache; a < &arp->cache[NCACHE]; a++){

-			memset(a->ip, 0, sizeof(a->ip));

-			memset(a->mac, 0, sizeof(a->mac));

 			a->hash = nil;

 			a->nextrxt = nil;

 			a->ifc = nil;

@@ -389,7 +383,7 @@

 		freeblistchain(arp->dropf);

 		arp->dropf = arp->dropl = nil;

 		arp->rxmt[0] = arp->rxmt[1] = nil;

-		qunlock(arp);

+		wunlock(arp);

 	} else if(strcmp(f[0], "add") == 0){

 		switch(n){

 		default:

@@ -436,13 +430,13 @@

 			error(Ebadarg);

 		if (parseip(ip, f[1]) == -1)

 			error(Ebadip);

-		qlock(arp);

-		for(a = arp->hash[haship(ip)]; a != nil; a = x){

+		wlock(arp);

+		for(a = arp->hash[hashipa(ip)]; a != nil; a = x){

 			x = a->hash;

 			if(ipcmp(ip, a->ip) == 0)

 				cleanarpent(arp, a);

 		}

-		qunlock(arp);

+		wunlock(arp);

 	} else

 		error(Ebadarp);

@@ -472,17 +466,17 @@

 			continue;

 		rlock(ifc);

-		qlock(arp);

-		state = arpstate[a->state];

+		rlock(arp);

 		ipmove(ip, a->ip);

-		if(ifc->m == nil || a->ifcid != ifc->ifcid || !ipv6local(ifc, ia, 0, ip)){

-			qunlock(arp);

+		if(ifc->m == nil || a->state == 0 || a->ifc != ifc || a->ifcid != ifc->ifcid || !ipv6local(ifc, ia, 0, ip)){

+			runlock(arp);

 			runlock(ifc);

 			continue;

 		}

 		mname = ifc->m->name;

+		state = arpstate[a->state];

 		convmac(mac, a->mac, ifc->m->maclen);

-		qunlock(arp);

+		runlock(arp);

 		runlock(ifc);

 		n = snprint(up->genbuf, sizeof up->genbuf,

@@ -538,7 +532,7 @@

 	Block *bp;

 	Ipifc *ifc;

-	qlock(arp);

+	wlock(arp);

 	/* retransmit ipv6 solicitations */

 	while((a = arp->rxmt[0]) != nil && NOW - a->ctime > 3*RETRANS_TIMER/4){

@@ -546,7 +540,8 @@

 			if(a->ifcid == ifc->ifcid){

 				ndpsendsol(arp->f, ifc, a);	/* unlocks arp */

 				runlock(ifc);

-				qlock(arp);

+

+				wlock(arp);

 				continue;

 			}

 			runlock(ifc);

@@ -561,7 +556,7 @@

 	bp = arp->dropf;

 	arp->dropf = arp->dropl = nil;

-	qunlock(arp);

+	wunlock(arp);

 	return bp;

 }

--- a/sys/src/9/ip/ethermedium.c

+++ b/sys/src/9/ip/ethermedium.c

@@ -267,7 +267,7 @@

 		bp = multicastarp(er->f, a, ifc->m, mac);

 		if(bp == nil){

 			/* don't do anything if it's been less than a second since the last */

-			if(NOW - a->ctime < RETRANS_TIMER){

+			if(a->utime - a->ctime < RETRANS_TIMER){

 				arprelease(er->f->arp, a);

 				return;

 			}

@@ -284,6 +284,9 @@

 			return;

 		}

 	}

+

+	/* need to have single block */

+	assert(bp->list == nil);

 	/* make it a single block with space for the ether header */

 	bp = padblock(bp, ifc->m->hsize);

--- a/sys/src/9/ip/ipifc.c

+++ b/sys/src/9/ip/ipifc.c

@@ -53,7 +53,7 @@

 };

 /* quick hash for ip addresses */

-#define hashipa(a) ( ( ((a)[IPaddrlen-2]<<8) | (a)[IPaddrlen-1] )%NHASH )

+#define hashipa(a) (((a)[IPaddrlen-2] + (a)[IPaddrlen-1])%NHASH)

 static char tifc[] = "ifc ";