from cinap:

aux/listen: rfork with RFREND

child processes handling the connection should be all
independent of each another and not share rendezvous
group. the rendezvous group sharing caused a bug in
exportfs when we switched from using pid to memory
address as rendezvous tag.

Reference: /n/atom/patch/applied/listenrfrend
Date: Thu Mar 13 14:17:25 CET 2014
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/aux/listen.c	Thu Mar 13 14:17:14 2014
+++ /sys/src/cmd/aux/listen.c	Thu Mar 13 14:17:15 2014
@@ -167,7 +167,7 @@
 	 * changing of console environment variables
 	 * erase privileged crypt state
 	 */
-	switch(rfork(RFNOTEG|RFPROC|RFFDG|RFNOWAIT|RFENVG|RFNAMEG)) {
+	switch(rfork(RFNOTEG|RFPROC|RFFDG|RFNOWAIT|RFENVG|RFNAMEG|RFREND)) {
 	case -1:
 		error("fork");
 	case 0:
@@ -266,9 +266,15 @@
  *  make a list of all services to announce for
  */
 void
-addannounce(char *str)
+addannounce(char *fmt, ...)
 {
 	Announce *a, **l;
+	char str[128];
+	va_list arg;
+
+	va_start(arg, fmt);
+	vseprint(str, str+sizeof(str), fmt, arg);
+	va_end(arg);
 
 	/* look for duplicate */
 	l = &announcements;
@@ -292,10 +298,17 @@
  *  delete a service for announcement list
  */
 void
-delannounce(char *str)
+delannounce(char *fmt, ...)
 {
 	Announce *a, **l;
 
+	char str[128];
+	va_list arg;
+
+	va_start(arg, fmt);
+	vseprint(str, str+sizeof(str), fmt, arg);
+	va_end(arg);
+
 	/* look for service */
 	l = &announcements;
 	for(a = announcements; a; a = a->next){
@@ -330,7 +343,6 @@
 {
 	int fd, i, n, nlen;
 	char *nm;
-	char ds[128];
 	Dir *db;
 
 	fd = open(dname, OREAD);
@@ -341,15 +353,14 @@
 	while((n=dirread(fd, &db)) > 0){
 		for(i=0; i<n; i++){
 			nm = db[i].name;
-			if(!(db[i].qid.type&QTDIR) &&
-			    strncmp(nm, proto, nlen) == 0) {
-				snprint(ds, sizeof ds, "%s!*!%s", protodir,
-					nm + nlen);
-				if (ignore(dname, nm))
-					delannounce(ds);
-				else
-					addannounce(ds);
-			}
+			if(db[i].qid.type&QTDIR ||
+			    strncmp(nm, proto, nlen) != 0 ||
+			    ignore(dname, nm))
+				continue;
+			if (ignore(dname, nm))
+				delannounce("%s!*!%s", protodir, nm+nlen);
+			else
+				addannounce("%s!*!%s", protodir, nm+nlen);
 		}
 		free(db);
 	}
@@ -386,7 +397,6 @@
 		if(nctl < 0){
 			if(!quiet)
 				syslog(1, listenlog, "listen: %r");
-			sleep(10*1000);
 			return;
 		}
 
@@ -397,6 +407,7 @@
 		case -1:
 			reject(nctl, ndir, "host overloaded");
 			close(nctl);
+			sleep(10*1000);
 			continue;
 		case 0:
 			/*
--- /sys/src/cmd/aux/listen1.c	Thu Mar 13 14:17:16 2014
+++ /sys/src/cmd/aux/listen1.c	Thu Mar 13 14:17:17 2014
@@ -90,7 +90,7 @@
 		if(nctl < 0)
 			sysfatal("listen %s: %r", argv[0]);
 
-		switch(rfork(RFFDG|RFPROC|RFNOWAIT|RFENVG|RFNAMEG|RFNOTEG)){
+		switch(rfork(RFFDG|RFPROC|RFNOWAIT|RFENVG|RFNAMEG|RFNOTEG|RFREND)){
 		case -1:
 			reject(nctl, ndir, "host overloaded");
 			close(nctl);
--- /sys/src/cmd/aux/xlisten.c	Thu Mar 13 14:17:18 2014
+++ /sys/src/cmd/aux/xlisten.c	Thu Mar 13 14:17:18 2014
@@ -11,6 +11,8 @@
 	Breakexec	= 0,		/* test with broken exec */
 
 	Maxincall	= 10,		/* botch */
+	Maxmaxincall	= 100,
+
 	Unset		= ~0,
 
 	Scanms		= 10*1000,	/* should be 60*1000 */
@@ -21,7 +23,7 @@
 	Debug		= Dtrace,
 };
 
-#define dprint(c, ...) do if(Debug & (c))fprint(2, __VA_ARGS__); while(0)
+#define dprint(c, ...) do if(debug & (c))fprint(2, __VA_ARGS__); while(0)
 
 enum {
 	Timer,
@@ -98,6 +100,9 @@
 	char	*srvtab[Nsrvtype];
 };
 
+int	debug		= Debug;
+int	maxincall	= Maxincall;
+
 static void
 llog(char *fmt, ...)
 {
@@ -186,7 +191,8 @@
 	return r;
 }
 
-void keepalive(int fd)
+void
+keepalive(int fd)
 {
 	fprint(fd, "keepalive");
 }
@@ -269,7 +275,7 @@
 {
 	Incall *i;
 	enum {
-		Flags = RFFDG|RFPROC|RFENVG|RFNAMEG|RFNOTEG,
+		Flags = RFFDG|RFPROC|RFENVG|RFNAMEG|RFNOTEG|RFREND,
 	};
 
 	USED(afd);
@@ -277,7 +283,7 @@
 	i = recvp(l->incalls);
 	if(i == nil)
 		return -1;
-	print("%s: recvp slot %d\n", l->ds, i->slot);
+	dprint(Dtrace, "%s: recvp slot %d\n", l->ds, i->slot);
 	i->pid = Unset;
 
 redux:
@@ -285,7 +291,7 @@
 	if(i->cfd == -1){
 		sendp(l->incalls, i);
 		if(l->fatal){
-			print("%s: fatal in listen\n", l->ds);
+			dprint(Dtrace, "%s: fatal in listen\n", l->ds);
 			return -1;
 		}
 		llog("listen: %r");
@@ -303,7 +309,7 @@
 	}
 	i->pid = recvul(l->pidchan);
 	close(i->cfd);
-	print("%s: slot %d pid %d\n", l->ds, i->slot, i->pid);
+	dprint(Dtrace, "%s: slot %d pid %d\n", l->ds, i->slot, i->pid);
 	if(i->pid == -1){
 		/*
 		 * assume the script can't be exec'd due to bad
@@ -311,7 +317,8 @@
 		 * until the script is changed.
 		 */
 		l->wait[i->slot] = nil;
-		print("pid is %d\n", i->pid);
+		dprint(Dtrace, "pid is %d (can't exec; penalty=1)\n", i->pid);
+		llog("%s/%s: can't exec: won't exec until changed", l->largs->srv, l->es);
 		l->penalty = 1;
 		return -1;
 	}
@@ -355,7 +362,7 @@
 	int i, sz;
 
 	dprint(Dtrace, "newserver %s\n", l->ds);
-	l->nincall = Maxincall;
+	l->nincall = maxincall;
 	l->incalls = chancreate(sizeof(Incall*), l->nincall);
 	l->pidchan = chancreate(sizeof(ulong), 1);
 
@@ -713,7 +720,7 @@
 void
 usage(void)
 {
-	fprint(2, "usage: xlisten [-n nsfile] [-N nsfile] [-d dir] [-t trust] [netdir] ...\n");
+	fprint(2, "usage: xlisten [-m maxincall] [-n nsfile] [-N nsfile] [-d dir] [-t trust] [netdir] ...\n");
 	threadexits("");
 }
 
@@ -746,6 +753,12 @@
 		if(checkdir(p->srvtab[Trust], Okdir) == -1)
 			sysfatal("xlisten: service directory doesn't exist: %r");
 		break;
+	case 'm':
+		maxincall = atoi(EARGF(usage()));
+		if(maxincall == -1 || maxincall > Maxmaxincall)
+			maxincall = Maxmaxincall;
+		if(maxincall <= 0)
+			sysfatal("xlisten: maxincall must be positive");
 	default:
 		usage();
 	}ARGEND