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kernel: devskel: use RWlock

--- a/sys/src/9/port/devskel.c

+++ b/sys/src/9/port/devskel.c

@@ -9,8 +9,8 @@

 typedef struct Skel Skel;

 struct Skel {

+	RWlock;

 	int ref;

-	QLock lk;

 	char name[KNAMELEN];

 	char mode;

 };

@@ -17,7 +17,7 @@

 struct

 {

-	QLock lk;

+	QLock;

 	ulong path;

 } skelalloc;

@@ -36,19 +36,26 @@

 	c = devattach('z', spec);

-	f = smalloc(sizeof *f);

-	if(spec != nil && spec[0] != '\0' && strchr("de", spec[0]) != nil)

-		f->mode = spec[0];

-	else

+	f = mallocz(sizeof *f, 1);

+	if(f == nil)

+		exhausted("memory");

+	if(waserror()){

+		free(f);

+		nexterror();

+	}

+

+	if(spec == nil)

 		f->mode = 'f';

+	else

+		f->mode = spec[0];

-	f->ref = 1;

-

-	qlock(&skelalloc.lk);

+	eqlock(&skelalloc);

 	path = skelalloc.path++;

-	qunlock(&skelalloc.lk);

+	qunlock(&skelalloc);

-	mkqid(&c->qid, NETQID(path, Qroot), 0, QTDIR);

+	poperror();

+	mkqid(&c->qid, NETQID(path, Qroot), path, QTDIR);

+	f->ref = 1;

 	c->aux = f;

 	return c;

 }

@@ -59,19 +66,25 @@

 	Skel *f;

 	Qid qid;

 	ulong perm;

-	uvlong path;

+	int path;

 	char *name;

 	perm = 0555|DMDIR;

 	path = NETTYPE(c->qid.path);

 	f = c->aux;

+	rlock(f);

+	if(waserror()){

+		runlock(f);

+		return -1;

+	}

 	name = f->name;

 	path += direction;

-	if(!f->name[0] && path != Qroot)

-		return -1;

+	if(!f->name[0] && path > Qroot)

+		error(Enonexist);

 	switch(path){

+	case Qroot-1:

 	case Qroot:

 		mkqid(&qid, Qroot, 0, QTDIR);

 		name = "#z";

@@ -92,28 +105,40 @@

 		}

 		break;

 	default:

-		return -1;

+		error(Enonexist);

 	}

-	qid.path = NETQID(NETID(c->qid.path), qid.path);

+	qid.vers = NETID(c->qid.path);

+	qid.path = NETQID(qid.vers, qid.path);

 	devdir(c, qid, name, 0, eve, perm, dp);

+	runlock(f);

+	poperror();

 	return 1;

 }

 static int

-skelgen(Chan *c, char *name, Dirtab *, int, int s, Dir *dp)

+skelgen(Chan *c, char *name, Dirtab*, int, int s, Dir *dp)

 {

 	Skel *f;

+	switch(s){

+	case DEVDOTDOT:

+		break;

+	case 0:

+		s++;

+		break;

+	default:

+		return -1;

+	}

 	f = c->aux;

-	//First walk away from root

-	if(name && !f->name[0] && f->mode != 'e' && NETTYPE(c->qid.path) == Qroot)

-		utfecpy(f->name, &f->name[sizeof f->name-1], name);

+	if(name && NETTYPE(c->qid.path) == Qroot){

+		wlock(f);

+		if(!f->name[0] && f->mode != 'e')

+			utfecpy(f->name, &f->name[sizeof f->name-1], name);

+		wunlock(f);

+	}

-	if(s != DEVDOTDOT)

-		s++;

-

 	return step(c, dp, s);

 }

@@ -123,21 +148,16 @@

 	Walkqid *wq;

 	Skel *f;

-	f = c->aux;

-	qlock(&f->lk);

-	if(waserror()){

-		qunlock(&f->lk);

-		nexterror();

-	}

-

 	wq = devwalk(c, nc, name, nname, nil, 0, skelgen);

-	if(wq != nil && wq->clone != nil && wq->clone != c){

-		if(f->ref <= 0)

-			panic("devskel ref");

-		f->ref++;

-	}

-	qunlock(&f->lk);

-	poperror();

+	if(wq == nil || wq->clone == nil)

+		return wq;

+

+	f = c->aux;

+	wlock(f);

+	if(f->ref <= 0)

+		panic("devskel ref");

+	f->ref++;

+	wunlock(f);

 	return wq;

 }

@@ -161,53 +181,35 @@

 	Skel *f;

 	f = c->aux;

-	qlock(&f->lk);

+	wlock(f);

 	f->ref--;

 	if(f->ref == 0){

-		qunlock(&f->lk);

+		wunlock(f);

 		free(f);

 	} else

-		qunlock(&f->lk);

+		wunlock(f);

 }

 static long

 skelread(Chan *c, void *va, long n, vlong)

 {

-	Skel *f;

-	long nout;

-

-	if(!(c->qid.type & QTDIR))

-		error(Eperm);

-

-	f = c->aux;

-	qlock(&f->lk);

-	if(waserror()){

-		qunlock(&f->lk);

-		nexterror();

-	}

-	nout = devdirread(c, va, n, nil, 0, skelgen);

-	qunlock(&f->lk);

-	poperror();

-	return nout;

+	return devdirread(c, va, n, nil, 0, skelgen);

 }

 static long

-skelwrite(Chan *, void *, long, vlong)

+skelwrite(Chan*, void*, long, vlong)

 {

-	error(Eperm);

-	return 0;

+	error(Ebadusefd);

+	return -1;

 }

 static int

 skelstat(Chan *c, uchar *db, int n)

 {

-	Skel *f;

 	Dir dir;

-	f = c->aux;

-	qlock(&f->lk);

-	step(c, &dir, 0);

-	qunlock(&f->lk);

+	if(step(c, &dir, 0) < 0)

+		error(Enonexist);

 	n = convD2M(&dir, db, n);

 	if(n < BIT16SZ)