10 files changed, 124 insertions(+), 101 deletions(-)

M ip/kio.c
M pc/vgacyber938x.c
M port/chan.c
M port/dev.c
M port/devcons.c
M port/devmnt.c
M port/pgrp.c
M port/portdat.h
M port/portfns.h
M port/sysfile.c

@@ 69,7 69,7 @@ kread(int fd, void *va, long n)
 			error(Etoosmall);
 	}
 
-	if(dir && c->mnt)
+	if(dir && c->mh)
 		n = unionread(c, va, n);
 	else if(devtab[c->type]->dc != L'M')
 		n = devtab[c->type]->read(c, va, n, c->offset);

@@ 11,6 11,11 @@
 #include <memdraw.h>
 #include "screen.h"
 
+enum {
+	CursorON	= 0xC8,
+	CursorOFF	= 0x00,
+};
+
 static int
 cyber938xpageset(VGAscr*, int page)
 {


@@ 67,7 72,7 @@ cyber938xlinear(VGAscr* scr, int* size, int* align)
 static void
 cyber938xcurdisable(VGAscr*)
 {
-	vgaxo(Crtx, 0x50, 0);
+	vgaxo(Crtx, 0x50, CursorOFF);
 }
 
 static void


@@ 94,39 99,12 @@ cyber938xcurload(VGAscr* scr, Cursor* curs)
 		*p++ = curs->set[2*y + 1]|curs->clr[2*y + 1];
 		*p++ = 0x00;
 		*p++ = 0x00;
-	}
-	while(y < 32){
-		*p++ = 0x00;
-		*p++ = 0x00;
-		*p++ = 0x00;
-		*p++ = 0x00;
-		y++;
-	}
-
-	/*
-	 * This is clearly not what's supposed to be done, but
-	 * without a proper datasheet this is what binary search
-	 * through the display memory gives as the place for the
-	 * pattern.
-	 * Note also that it seems the cursor image offset (CRT44
-	 * and CRT45) cannot be set above 512KB.
-	 * This will do for now as the ThinkPad 560E has 1MB and
-	 * can only manage 800x600x8.
-	 */
-	p += 512*1024 - 128;
-	for(y = 0; y < 16; y++){
 		*p++ = curs->set[2*y];
 		*p++ = curs->set[2*y + 1];
 		*p++ = 0x00;
 		*p++ = 0x00;
 	}
-	while(y < 32){
-		*p++ = 0x00;
-		*p++ = 0x00;
-		*p++ = 0x00;
-		*p++ = 0x00;
-		y++;
-	}
+	memset(p, 0, (32-y)*8);
 
 	if(!islinear){
 		cyber938xpageset(scr, opage);


@@ 137,7 115,7 @@ cyber938xcurload(VGAscr* scr, Cursor* curs)
 	 * Save the cursor hotpoint and enable the cursor.
 	 */
 	scr->offset = curs->offset;
-	vgaxo(Crtx, 0x50, 0xC8);
+	vgaxo(Crtx, 0x50, CursorON);
 }
 
 static int


@@ 195,10 173,10 @@ cyber938xcurenable(VGAscr* scr)
 	/*
 	 * Find a place for the cursor data in display memory.
 	 */
-	storage = ((scr->gscreen->width*BY2WD*scr->gscreen->r.max.y+1023)/1024)*2;
+	storage = ((scr->gscreen->width*BY2WD*scr->gscreen->r.max.y+1023)/1024);
 	vgaxo(Crtx, 0x44, storage & 0xFF);
 	vgaxo(Crtx, 0x45, (storage>>8) & 0xFF);
-	storage *= 512;
+	storage *= 1024;
 	scr->storage = storage;
 
 	/*


@@ 209,7 187,7 @@ cyber938xcurenable(VGAscr* scr)
 	 */
 	cyber938xcurload(scr, &arrow);
 	cyber938xcurmove(scr, ZP);
-	vgaxo(Crtx, 0x50, 0xC8);
+	vgaxo(Crtx, 0x50, CursorON);
 }
 
 VGAdev vgacyber938xdev = {

@@ 95,7 95,9 @@ newchan(void)
 	c->ref = 1;
 	c->dev = 0;
 	c->offset = 0;
-	c->mnt = 0;
+	c->mh = 0;
+	c->xmh = 0;
+	c->uri = 0;
 	c->aux = 0;
 	c->mchan = 0;
 	c->path = 0;


@@ 114,6 116,11 @@ chanfree(Chan *c)
 		c->session = 0;
 	}
 
+	if(c->mh != nil){
+		putmhead(c->mh);
+		c->mh = nil;
+	}
+
 	/*
 	 * Channel can be closed before a path is created or the last
 	 * channel in a mount which has already cleared its pt names


@@ 187,10 194,6 @@ cmount(Chan *new, Chan *old, int flag, char *spec)
 
 	pg = up->pgrp;
 	wlock(&pg->ns);
-	if(waserror()) {
-		wunlock(&pg->ns);
-		nexterror();
-	}
 
 	l = &MOUNTH(pg, old);
 	for(m = *l; m; m = m->hash) {


@@ 205,6 208,7 @@ cmount(Chan *new, Chan *old, int flag, char *spec)
 		 *  head and add to the hash table.
 		 */
 		m = smalloc(sizeof(Mhead));
+		m->ref = 1;
 		m->from = old;
 		incref(old);
 		m->hash = *l;


@@ 217,9 221,15 @@ cmount(Chan *new, Chan *old, int flag, char *spec)
 		if(order != MREPL)
 			m->mount = newmount(m, old, 0, 0);
 	}
+	wlock(&m->lock);
+	if(waserror()){
+		wunlock(&m->lock);
+		nexterror();
+	}
+	wunlock(&pg->ns);
 
 	nm = newmount(m, new, flag, spec);
-	if(new->mnt != 0) {
+	if(new->mh != nil && new->mh->mount != nil) {
 		/*
 		 *  copy a union when binding it onto a directory
 		 */


@@ 227,7 237,8 @@ cmount(Chan *new, Chan *old, int flag, char *spec)
 		if(order == MREPL)
 			flg = MAFTER;
 		h = &nm->next;
-		for(um = new->mnt->next; um; um = um->next) {
+		um = new->mh->mount;
+		for(um = um->next; um; um = um->next) {
 			f = newmount(m, um->to, flg, um->spec);
 			*h = f;
 			h = &f->next;


@@ 254,7 265,7 @@ cmount(Chan *new, Chan *old, int flag, char *spec)
 		m->mount = nm;
 	}
 
-	wunlock(&pg->ns);
+	wunlock(&m->lock);
 	poperror();
 	return nm->mountid;
 }


@@ 281,14 292,18 @@ cunmount(Chan *mnt, Chan *mounted)
 		error(Eunmount);
 	}
 
+	wlock(&m->lock);
 	if(mounted == 0) {
 		*l = m->hash;
 		wunlock(&pg->ns);
 		mountfree(m->mount);
+		m->mount = nil;
 		cclose(m->from);
-		free(m);
+		wunlock(&m->lock);
+		putmhead(m);
 		return;
 	}
+	wunlock(&pg->ns);
 
 	p = &m->mount;
 	for(f = *p; f; f = f->next) {


@@ 298,19 313,20 @@ cunmount(Chan *mnt, Chan *mounted)
 			*p = f->next;
 			f->next = 0;
 			mountfree(f);
-			if(m->mount == 0) {
+			if(m->mount == nil) {
 				*l = m->hash;
 				wunlock(&pg->ns);
 				cclose(m->from);
-				free(m);
+				wunlock(&m->lock);
+				putmhead(m);
 				return;
 			}
-			wunlock(&pg->ns);
+			wunlock(&m->lock);
 			return;
 		}
 		p = &f->next;
 	}
-	wunlock(&pg->ns);
+	wunlock(&m->lock);
 	error(Eunion);
 }
 


@@ 329,24 345,34 @@ domount(Chan *c)
 
 	pg = up->pgrp;
 	rlock(&pg->ns);
-	if(waserror()) {
-		runlock(&pg->ns);
-		nexterror();
+	if(c->mh){
+		putmhead(c->mh);
+		c->mh = 0;
 	}
-	c->mnt = 0;
 
-	for(m = MOUNTH(pg, c); m; m = m->hash)
+	for(m = MOUNTH(pg, c); m; m = m->hash){
+		rlock(&m->lock);
 		if(eqchan(m->from, c, 1)) {
+			if(waserror()) {
+				runlock(&m->lock);
+				nexterror();
+			}
+			runlock(&pg->ns);
 			nc = cclone(m->mount->to, 0);
-			nc->mnt = m->mount;
-			nc->xmnt = nc->mnt;
-			nc->mountid = m->mount->mountid;
+			if(nc->mh != nil)
+				putmhead(nc->mh);
+			nc->mh = m;
+			nc->xmh = m;
+			incref(m);
 			cclose(c);
 			c = nc;
-			break;
+			poperror();
+			runlock(&m->lock);
+			return c;
 		}
+		runlock(&m->lock);
+	}
 
-	poperror();
 	runlock(&pg->ns);
 	return c;
 }


@@ 387,7 413,6 @@ undomount(Chan *c)
 int
 walk(Chan **cp, char *name, int domnt)
 {
-	Pgrp *pg;
 	Chan *c, *ac;
 	Mount *f;
 	int dotdot;


@@ 412,20 437,19 @@ walk(Chan **cp, char *name, int domnt)
 		return 0;
 	}
 
-	if(ac->mnt == nil)
+	if(ac->mh == nil)
 		return -1;
 
 	c = nil;
-	pg = up->pgrp;
 
-	rlock(&pg->ns);
+	rlock(&ac->mh->lock);
 	if(waserror()) {
-		runlock(&pg->ns);
+		runlock(&ac->mh->lock);
 		if(c)
 			cclose(c);
 		nexterror();
 	}
-	for(f = ac->mnt; f; f = f->next) {
+	for(f = ac->mh->mount; f; f = f->next) {
 		c = cclone(f->to, 0);
 		c->flag &= ~CCREATE;	/* not inherited through a walk */
 		if(devtab[c->type]->walk(c, name) != 0)


@@ 434,7 458,7 @@ walk(Chan **cp, char *name, int domnt)
 		c = nil;
 	}
 	poperror();
-	runlock(&pg->ns);
+	runlock(&ac->mh->lock);
 
 	if(c == nil)
 		return -1;


@@ 442,7 466,10 @@ walk(Chan **cp, char *name, int domnt)
 	if(dotdot)
 		c = undomount(c);
 
-	c->mnt = 0;
+	if(c->mh){
+		putmhead(c->mh);
+		c->mh = nil;
+	}
 	if(domnt) {
 		if(waserror()) {
 			cclose(c);


@@ 462,21 489,22 @@ walk(Chan **cp, char *name, int domnt)
 Chan*
 createdir(Chan *c)
 {
-	Pgrp *pg;
 	Chan *nc;
 	Mount *f;
 
-	pg = up->pgrp;
-	rlock(&pg->ns);
+	rlock(&c->mh->lock);
 	if(waserror()) {
-		runlock(&pg->ns);
+		runlock(&c->mh->lock);
 		nexterror();
 	}
-	for(f = c->mnt; f; f = f->next) {
+	for(f = c->mh->mount; f; f = f->next) {
 		if(f->to->flag&CCREATE) {
 			nc = cclone(f->to, 0);
-			nc->mnt = f;
-			runlock(&pg->ns);
+			if(nc->mh != nil)
+				putmhead(nc->mh);
+			nc->mh = c->mh;
+			incref(c->mh);
+			runlock(&c->mh->lock);
 			poperror();
 			cclose(c);
 			return nc;


@@ 604,7 632,6 @@ namec(char *name, int amode, int omode, ulong perm)
 		if(*name == 0)
 			isdot = 1;
 	}
-	c->mnt = nil;
 
 	if(waserror()){
 		cclose(c);


@@ 708,7 735,7 @@ namec(char *name, int amode, int omode, ulong perm)
 		/*
 		 *  the file didn't exist, try the create
 		 */
-		if(c->mnt && !(c->flag&CCREATE))
+		if(c->mh != nil && !(c->flag&CCREATE))
 			c = createdir(c);
 
 		/*


@@ 813,3 840,10 @@ isdir(Chan *c)
 		return;
 	error(Enotdir);
 }
+
+void
+putmhead(Mhead *m)
+{
+	if(decref(m) == 0)
+		free(m);
+}

@@ 93,7 93,9 @@ devclone(Chan *c, Chan *nc)
 	nc->qid = c->qid;
 	nc->offset = c->offset;
 	nc->flag = c->flag;
-	nc->mnt = c->mnt;
+	nc->mh = c->mh;
+	if(c->mh != nil)
+		incref(c->mh);
 	nc->mountid = c->mountid;
 	nc->aux = c->aux;
 	nc->mchan = c->mchan;

@@ 900,7 900,7 @@ Dev consdevtab = {
 	devwstat,
 };
 
-static struct
+struct Rb
 {
 	QLock;
 	Rendez	producer;


@@ 964,8 964,8 @@ genrandom(void*)
 		for(;;)
 			if(++rb.randomcount > 100000)
 				break;
-			if(anyhigher())
-				sched();
+		if(anyhigher())
+			sched();
 		if(!rbnotfull(0))
 			sleep(&rb.producer, rbnotfull, 0);
 	}

@@ 893,7 893,7 @@ recoverchan(Mnt *m, Chan *c)
 	}
 
 	/* Attach the fid onto the file server (sets c->path to #Mxxx) */
-	mattach(m, c, c->xmnt->spec);
+	mattach(m, c, c->xmh->mount->spec);
 	poperror();
 
 	/*

@@ 82,10 82,13 @@ closepgrp(Pgrp *p)
 	e = &p->mnthash[MNTHASH];
 	for(h = p->mnthash; h < e; h++) {
 		for(f = *h; f; f = next) {
+			wlock(&f->lock);
 			cclose(f->from);
 			mountfree(f->mount);
+			f->mount = nil;
 			next = f->hash;
-			free(f);
+			wunlock(&f->lock);
+			putmhead(f);
 		}
 	}
 	wunlock(&p->ns);


@@ 130,8 133,10 @@ pgrpcpy(Pgrp *to, Pgrp *from)
 	for(i = 0; i < MNTHASH; i++) {
 		l = tom++;
 		for(f = from->mnthash[i]; f; f = f->hash) {
+			rlock(&f->lock);
 			mh = smalloc(sizeof(Mhead));
 			mh->from = f->from;
+			mh->ref = 1;
 			incref(mh->from);
 			*l = mh;
 			l = &mh->hash;


@@ 149,6 154,7 @@ pgrpcpy(Pgrp *to, Pgrp *from)
 				*link = n;
 				link = &n->next;
 			}
+			runlock(&f->lock);
 		}
 	}
 	/*

@@ 150,8 150,9 @@ struct Chan
 	Qid	qid;
 	int	fid;			/* for devmnt */
 	Path*	path;
-	Mount*	mnt;			/* mount point that derived Chan */
-	Mount*	xmnt;			/* Last mount point crossed */
+	Mhead*	mh;			/* mount point that derived Chan */
+	Mhead*	xmh;			/* Last mount point crossed */
+	int	uri;			/* union read index */
 	ulong	mountid;
 	Mntcache *mcp;			/* Mount cache pointer */
 	union {


@@ 232,6 233,8 @@ struct Mount
 
 struct Mhead
 {
+	Ref;
+	RWlock	lock;
 	Chan*	from;			/* channel mounted upon */
 	Mount*	mount;			/* what's mounted upon it */
 	Mhead*	hash;			/* Hash chain */

@@ 203,6 203,7 @@ int		ptpath(Path*, char*, int);
 int		pullblock(Block**, int);
 Block*		pullupblock(Block*, int);
 void		putimage(Image*);
+void		putmhead(Mhead*);
 void		putmmu(ulong, ulong, Page*);
 void		putpage(Page*);
 void		putseg(Segment*);

@@ 279,28 279,26 @@ sysclose(ulong *arg)
 long
 unionread(Chan *c, void *va, long n)
 {
+	int i;
 	long nr;
 	Chan *nc;
-	Pgrp *pg;
+	Mhead *m;
+	Mount *mount;
 
-	pg = up->pgrp;
-	rlock(&pg->ns);
+	m = c->mh;
+	rlock(&m->lock);
+	mount = m->mount;
+	for(i = 0; mount != nil && i < c->uri; i++)
+		mount = mount->next;
 
 	for(;;) {
 		if(waserror()) {
-			runlock(&pg->ns);
+			runlock(&m->lock);
 			nexterror();
 		}
-		nc = cclone(c->mnt->to, 0);
+		nc = cclone(mount->to, 0);
 		poperror();
 
-		if(c->mountid != c->mnt->mountid) {
-			pprint("unionread: changed underfoot?\n");
-			runlock(&pg->ns);
-			cclose(nc);
-			return 0;
-		}
-
 		/* Error causes component of union to be skipped */
 		if(waserror()) {
 			cclose(nc);


@@ 316,18 314,18 @@ unionread(Chan *c, void *va, long n)
 
 		cclose(nc);
 		if(nr > 0) {
-			runlock(&pg->ns);
+			runlock(&m->lock);
 			return nr;
 		}
 		/* Advance to next element */
 	next:
-		c->mnt = c->mnt->next;
-		if(c->mnt == 0)
+		c->uri++;
+		mount = mount->next;
+		if(mount == nil)
 			break;
-		c->mountid = c->mnt->mountid;
 		c->offset = 0;
 	}
-	runlock(&pg->ns);
+	runlock(&m->lock);
 	return 0;
 }
 


@@ 354,7 352,7 @@ sysread9p(ulong *arg)
 			error(Etoosmall);
 	}
 
-	if(dir && c->mnt)
+	if(dir && c->mh)
 		n = unionread(c, (void*)arg[1], n);
 	else if(devtab[c->type]->dc != L'M')
 		n = devtab[c->type]->read(c, (void*)arg[1], n, c->offset);


@@ 394,7 392,7 @@ sysread(ulong *arg)
 			error(Etoosmall);
 	}
 
-	if(dir && c->mnt)
+	if(dir && c->mh)
 		n = unionread(c, (void*)arg[1], n);
 	else
 		n = devtab[c->type]->read(c, (void*)arg[1], n, c->offset);


@@ 514,6 512,7 @@ sseek(ulong *arg)
 		break;
 	}
 	*(vlong*)arg[0] = off;
+	c->uri = 0;
 	cclose(c);
 	poperror();
 }