sharpen up adding and removing consoles on the fly.
in the process we're going to lose the qlock conversion,
unfortunately.

Reference: /n/atom/patch/applied2013/consolefsupd
Date: Wed Jun 19 02:57:19 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/aux/consolefs.c	Wed Jun 19 02:56:20 2013
+++ /sys/src/cmd/aux/consolefs.c	Wed Jun 19 02:56:20 2013
@@ -47,14 +47,14 @@
 
 struct Reqlist
 {
-	QLock;
+	Lock;
 	Request	*first;
 	Request *last;
 };
 
 struct Fid
 {
-	QLock;
+	Lock;
 	Fid	*next;			/* hash list */
 	Fid	*cnext;			/* list of Fid's on a console */
 	int	fid;
@@ -91,6 +91,7 @@
 {
 	QLock;
 
+	int	mark;
 	Parm;
 
 	int	pid;			/* pid of reader */
@@ -105,7 +106,7 @@
 
 struct Fs
 {
-	QLock;
+	Lock;
 
 	int	fd;			/* to kernel mount point */
 	int	messagesize;
@@ -130,7 +131,6 @@
 extern	void	fsauth(Fs*, Request*, Fid*);
 extern	void	fsattach(Fs*, Request*, Fid*);
 extern	void	fswalk(Fs*, Request*, Fid*);
-extern	void	fsclwalk(Fs*, Request*, Fid*);
 extern	void	fsopen(Fs*, Request*, Fid*);
 extern	void	fscreate(Fs*, Request*, Fid*);
 extern	void	fsread(Fs*, Request*, Fid*);
@@ -220,14 +220,14 @@
 void
 addreq(Reqlist *l, Request *r)
 {
-	qlock(l);
+	lock(l);
 	if(l->first == nil)
 		l->first = r;
 	else
 		l->last->next = r;
 	l->last = r;
 	r->next = nil;
-	qunlock(l);
+	unlock(l);
 }
 
 /*
@@ -238,11 +238,11 @@
 {
 	Request *r;
 
-	qlock(l);
+	lock(l);
 	r = l->first;
 	if(r != nil)
 		l->first = r->next;
-	qunlock(l);
+	unlock(l);
 	return r;
 }
 
@@ -254,17 +254,17 @@
 {
 	Request *or, **ll;
 
-	qlock(l);
+	lock(l);
 	ll = &l->first;
 	for(or = *ll; or; or = or->next){
 		if(or->f.tag == tag){
 			*ll = or->next;
-			qunlock(l);
+			unlock(l);
 			return or;
 		}
 		ll = &or->next;
 	}
-	qunlock(l);
+	unlock(l);
 	return nil;
 }
 
@@ -434,12 +434,12 @@
 {
 	if(c->pid > 0){
 		if(postnote(PNPROC, c->pid, msg) != 0)
-			fprint(2, "postnote failed: %r\n");
+			fprint(2, "consolefs: postnote failed: cfd pid: %r\n");
 		c->pid = 0;
 	}
 	if(c->cpid > 0){
 		if(postnote(PNPROC, c->cpid, msg) != 0)
-			fprint(2, "postnote failed: %r\n");
+			fprint(2, "consolefs: postnote failed: cfd cpid: %r\n");
 		c->cpid = 0;
 	}
 	close(c->fd);
@@ -547,6 +547,38 @@
 	return c;
 }
 
+void
+rmconsole(Fs *fs, Console *c)
+{
+	Fid *f, **l, *fl;
+	Request *nr;
+
+	if(debug)
+		fprint(2, "rmconsole %s:%s\n", c->name, c->dev);
+
+	closeconsfds(c, "die jedi scum");
+	free(c->name);
+	free(c->dev);
+
+	while(f = c->flist){
+		while((nr = remreq(&f->r)) != nil){
+			fprint(2, "reply %#p\n", nr);
+			fsreply(fs, nr, "console gone");
+		}
+
+		qlock(c);
+		for(l = &c->flist; *l; l = &fl->cnext){
+			fl = *l;
+			if(fl == f){
+				*l = fl->cnext;
+				break;
+			}
+		}
+		qunlock(c);
+	}
+	free(c);
+}
+
 /*
  *  buffer data from console to a client.
  *  circular q with writer able to catch up to reader.
@@ -558,7 +590,7 @@
 	char *rp, *wp, *ep;
 	int pass;
 
-	qlock(f);
+	lock(f);
 	rp = f->rp;
 	wp = f->wp;
 	ep = f->buf + sizeof(f->buf);
@@ -582,7 +614,7 @@
 		else
 			f->rp = wp;
 	}
-	qunlock(f);
+	unlock(f);
 }
 
 /*
@@ -613,6 +645,8 @@
 void
 handler(void*, char *msg)
 {
+	if(debug)
+		fprint(2, "handler %s\n", msg);
 	if(strstr(msg, "reopen") != nil ||
 	   strstr(msg, "write on closed pipe") != nil)
 		noted(NCONT);
@@ -659,7 +693,7 @@
 	c->pid = 0;
 	if(c->cpid > 0){
 		if(postnote(PNPROC, c->cpid, "reopen") != 0)
-			fprint(2, "postnote failed: %r\n");
+			fprint(2, "consolefs: postnote failed: fsreader: %r\n");
 		c->cpid = 0;
 	}
 	qunlock(c);
@@ -668,10 +702,16 @@
 void
 readdb(Fs *fs)
 {
+	int i;
+	Console *c;
 	Parm p;
 	Ndbs s;
 	Ndbtuple *t, *nt;
 
+	/* clear marks */
+	for(i = 0; i < fs->ncons; i++)
+		fs->cons[i]->mark = 0;
+
 	memset(&s, 0, sizeof s);
 	db = ndbreopendb(db);		/* need for database=; botch ndbsearch should do */
 
@@ -694,10 +734,26 @@
 			else if(strcmp(nt->attr, "openondemand") == 0)
 				p.ondemand = 1;
 		}
-		if(p.dev != nil && p.name != nil)
-			console(fs, p);
+		if(p.dev != nil && p.name != nil){
+			c = console(fs, p);
+			if(c != nil)
+				c->mark = 1;
+		}
 		ndbfree(t);
 	}
+
+	/* sweep consoles */
+	for(i = 0; i < fs->ncons;){
+		c = fs->cons[i];
+		if(c->mark){
+			c->mark = 0;
+			i++;
+			continue;
+		}
+		rmconsole(fs, c);
+		memmove(fs->cons+i, fs->cons+i+1, (--fs->ncons - i) * sizeof c);
+		fs->cons[fs->ncons] = 0;
+	}
 }
 
 int dbmtime;
@@ -759,11 +815,11 @@
 {
 	Fid *f, *nf;
 
-	qlock(fs);
+	lock(fs);
 	for(f = fs->hash[fid%Nhash]; f; f = f->next){
 		if(f->fid == fid){
 			f->ref++;
-			qunlock(fs);
+			unlock(fs);
 			return f;
 		}
 	}
@@ -775,7 +831,7 @@
 	nf->ref = 1;
 	nf->wp = nf->buf;
 	nf->rp = nf->wp;
-	qunlock(fs);
+	unlock(fs);
 	return nf;
 }
 
@@ -784,9 +840,9 @@
 {
 	Fid **l, *nf;
 
-	qlock(fs);
+	lock(fs);
 	if(--f->ref > 0){
-		qunlock(fs);
+		unlock(fs);
 		return;
 	}
 	for(l = &fs->hash[f->fid%Nhash]; nf = *l; l = &nf->next)
@@ -794,7 +850,7 @@
 			*l = f->next;
 			break;
 		}
-	qunlock(fs);
+	unlock(fs);
 	free(f->user);
 	free(f);
 }
@@ -853,9 +909,9 @@
 
 	/* hold down the fid till the clunk */
 	f->attached = 1;
-	qlock(fs);
+	lock(fs);
 	f->ref++;
-	qunlock(fs);
+	unlock(fs);
 
 	r->f.qid = f->qid;
 	fsreply(fs, r, nil);
@@ -1291,7 +1347,7 @@
 		qunlock(f->c);
 	}
 
-	qlock(f);
+	lock(f);
 	while(f->rp != f->wp){
 		r = remreq(&f->r);
 		if(r == nil)
@@ -1310,7 +1366,7 @@
 		r->f.count = p - (char*)r->buf;
 		fsreply(fs, r, nil);
 	}
-	qunlock(f);
+	unlock(f);
 }
 
 void