commit - 94d381ec9d579e5336f3817b68cf4d1a8a7333db
commit + 587933c16132d880a06ff99bd087e64a3a04975e
blob - 6269dfdaf11450560efbc0da3818aae3daf5401d
blob + 234cdf1b2c73a25a49c2ae2790cabfc678bf3f91
--- src/cmd/devdraw/devdraw.c
+++ src/cmd/devdraw/devdraw.c
@@ -14,6 +14,8 @@
 #include <drawfcall.h>
 #include "devdraw.h"
 
+QLock	drawlk;
+
 static	int		drawuninstall(Client*, int);
 static	Memimage*	drawinstall(Client*, int, Memimage*, DScreen*);
 static	void		drawfreedimage(Client*, DImage*);
@@ -47,14 +49,14 @@ gfx_replacescreenimage(Client *c, Memimage *m)
 	 */
 	Memimage *om;
 
-	qlock(&c->drawlk);
+	qlock(&drawlk);
 	om = c->screenimage;
 	c->screenimage = m;
 	m->screenref = 1;
 	if(om && --om->screenref == 0){
 		_freememimage(om);
 	}
-	qunlock(&c->drawlk);
+	qunlock(&drawlk);
 	gfx_mouseresized(c);
 }
 
@@ -142,9 +144,9 @@ addflush(Client *c, Rectangle r)
 		// and gfx thread might be blocked on drawlk trying to install a new screen
 		// during a resize.
 		rpc_gfxdrawunlock();
-		qunlock(&c->drawlk);
+		qunlock(&drawlk);
 		c->impl->rpc_flush(c, fr);
-		qlock(&c->drawlk);
+		qlock(&drawlk);
 		rpc_gfxdrawlock();
 	}
 }
@@ -187,9 +189,9 @@ drawflush(Client *c)
 		// and gfx thread might be blocked on drawlk trying to install a new screen
 		// during a resize.
 		rpc_gfxdrawunlock();
-		qunlock(&c->drawlk);
+		qunlock(&drawlk);
 		c->impl->rpc_flush(c, r);
-		qlock(&c->drawlk);
+		qlock(&drawlk);
 		rpc_gfxdrawlock();
 	}
 }
@@ -614,7 +616,7 @@ drawcoord(uchar *p, uchar *maxp, int oldx, int *newx)
 int
 draw_dataread(Client *cl, void *a, int n)
 {
-	qlock(&cl->drawlk);
+	qlock(&drawlk);
 	if(cl->readdata == nil){
 		werrstr("no draw data");
 		goto err;
@@ -627,11 +629,11 @@ draw_dataread(Client *cl, void *a, int n)
 	memmove(a, cl->readdata, cl->nreaddata);
 	free(cl->readdata);
 	cl->readdata = nil;
-	qunlock(&cl->drawlk);
+	qunlock(&drawlk);
 	return n;
 
 err:
-	qunlock(&cl->drawlk);
+	qunlock(&drawlk);
 	return -1;
 }
 
@@ -656,7 +658,7 @@ draw_datawrite(Client *client, void *v, int n)
 	Refreshfn reffn;
 	Refx *refx;
 
-	qlock(&client->drawlk);
+	qlock(&drawlk);
 	rpc_gfxdrawlock();
 	a = v;
 	m = 0;
@@ -1431,7 +1433,7 @@ draw_datawrite(Client *client, void *v, int n)
 		}
 	}
 	rpc_gfxdrawunlock();
-	qunlock(&client->drawlk);
+	qunlock(&drawlk);
 	return oldn - n;
 
 Enodrawimage:
@@ -1502,6 +1504,6 @@ Ebadarg:
 error:
 	werrstr("%s", err);
 	rpc_gfxdrawunlock();
-	qunlock(&client->drawlk);
+	qunlock(&drawlk);
 	return -1;
 }
blob - 1dac2d506f0ccd9d63dc2682cfc6a713db64f348
blob + 261d04d1efbaa3745c60131220fa30e4c678accb
--- src/cmd/devdraw/devdraw.h
+++ src/cmd/devdraw/devdraw.h
@@ -56,6 +56,8 @@ struct ClientImpl
 	void (*rpc_flush)(Client*, Rectangle);
 };
 
+extern QLock drawlk;
+
 struct Client
 {
 	int		rfd;
@@ -69,10 +71,9 @@ struct Client
 
 	char*	wsysid;
 
-	// drawlk protects the draw data structures.
+	// drawlk protects the draw data structures for all clients.
 	// It can be acquired by an RPC thread or a graphics thread
 	// but must not be held on one thread while waiting for the other.
-	QLock	drawlk;
 	/*Ref		r;*/
 	DImage*		dimage[NHASH];
 	CScreen*	cscreen;
blob - 9454be05d4cfd797629989c3f438b57a434f650b
blob + ad9c029e7661de4d1c32ef63605f87bba1a1780e
--- src/cmd/devdraw/mac-screen.m
+++ src/cmd/devdraw/mac-screen.m
@@ -39,7 +39,6 @@ static uint msec(void);
 
 static void	rpc_resizeimg(Client*);
 static void	rpc_resizewindow(Client*, Rectangle);
-static void	rpc_serve(Client*);
 static void	rpc_setcursor(Client*, Cursor*, Cursor2*);
 static void	rpc_setlabel(Client*, char*);
 static void	rpc_setmouse(Client*, Point);
@@ -496,17 +495,17 @@ rpc_flush(Client *client, Rectangle r)
 		if(!rectclip(&r, Rect(0, 0, self.dlayer.texture.width, self.dlayer.texture.height)) || !rectclip(&r, self.img->r))
 			return;
 
-		// self.client->drawlk protects the pixel data in self.img.
+		// drawlk protects the pixel data in self.img.
 		// In addition to avoiding a technical data race,
 		// the lock avoids drawing partial updates, which makes
 		// animations like sweeping windows much less flickery.
-		qlock(&self.client->drawlk);
+		qlock(&drawlk);
 		[self.dlayer.texture
 			replaceRegion:MTLRegionMake2D(r.min.x, r.min.y, Dx(r), Dy(r))
 			mipmapLevel:0
 			withBytes:byteaddr(self.img, Pt(r.min.x, r.min.y))
 			bytesPerRow:self.img->width*sizeof(u32int)];
-		qunlock(&self.client->drawlk);
+		qunlock(&drawlk);
 
 		NSRect nr = NSMakeRect(r.min.x, r.min.y, Dx(r), Dy(r));
 		dispatch_time_t time;