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Date:      Thu, 25 Oct 2007 20:55:49 +0300
From:      Kostik Belousov <kostikbel@gmail.com>
To:        pluknet <pluknet@gmail.com>
Cc:        anholt@freebsd.org, freebsd-stable@freebsd.org
Subject:   Re: drm(4) related LOR
Message-ID:  <20071025175548.GV2012@deviant.kiev.zoral.com.ua>
In-Reply-To: <a31046fc0710250437n3e1b455ftb15f7074a83a3955@mail.gmail.com>
References:  <a31046fc0710250437n3e1b455ftb15f7074a83a3955@mail.gmail.com>

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On Thu, Oct 25, 2007 at 03:37:32PM +0400, pluknet wrote:
> Hi all.
>=20
> I am getting the following LOR on my 7.0-BETA1:
>=20
> lock order reversal: (sleepable after non-sleepable)
> 1st 0xc3c904d8 drm device (drm device) @ /media/src/sys/modules/drm/drm/.=
./../..
> /dev/drm/drm_drv.c:907
> 2nd 0xc4135a3c user map (user map) @ vm/vm_glue.c:183
> KDB: stack backtrace:
> db_trace_self_wrapper(c076f2df,e6716a74,c055fcd6,c077168b,c4135a3c,...) a=
t db_tr
> ace_self_wrapper+0x26
> kdb_backtrace(c077168b,c4135a3c,c078accb,c078accb,c078a7e6,...) at kdb_ba=
cktrace
> +0x29
> witness_checkorder(c4135a3c,9,c078a7dd,b7,c4135a3c,...) at witness_checko=
rder+0x
> 6d6
> _sx_xlock(c4135a3c,0,c078a7dd,b7,e6716ad8,...) at _sx_xlock+0x7d
> _vm_map_lock_read(c41359f8,c078a7dd,b7,c078ac64,8,...) at _vm_map_lock_re=
ad+0x50
> useracc(28aab980,8,1,1,c076b1ec,...) at useracc+0x65
> i915_cmdbuffer(c4147100,8018644b,c52e8180,3,c492dc60,...) at i915_cmdbuff=
er+0x56
> 3
> drm_ioctl(c4147100,8018644b,c52e8180,3,c492dc60,...) at drm_ioctl+0x384
> giant_ioctl(c4147100,8018644b,c52e8180,3,c492dc60,...) at giant_ioctl+0x56
> devfs_ioctl_f(c5c146c0,8018644b,c52e8180,c5536500,c492dc60,...) at devfs_=
ioctl_f
> +0xd5
> kern_ioctl(c492dc60,5,8018644b,c52e8180,c52e8180,...) at kern_ioctl+0x253
> ioctl(c492dc60,e6716cfc,c,e6716d38,c07a92d0,...) at ioctl+0x13f
> syscall(e6716d38) at syscall+0x2f3
> Xint0x80_syscall() at Xint0x80_syscall+0x20
> --- syscall (54, FreeBSD ELF32, ioctl), eip =3D 0x28698a53, esp =3D 0xbf6=
f6c9c, ebp
> =3D 0xbf6f6cb8 ---
>=20
> It is first observed after update to 7.0-BETA1 (from CURRENT of Oct 11)
> $ ident /media/src/sys/dev/drm/drm_drv.c
> /media/src/sys/dev/drm/drm_drv.c:
>      $FreeBSD: src/sys/dev/drm/drm_drv.c,v 1.6 2006/09/07 23:04:47 anholt=
 Exp $
> $ ident /media/src/sys/vm/vm_glue.c
> /media/src/sys/vm/vm_glue.c:
>      $FreeBSD: src/sys/vm/vm_glue.c,v 1.225 2007/09/21 05:07:07 jeff Exp $
>=20
> Note that drm is kldloadable and is not statically compiled in a kernel.
> Thanks.

The folowing patch should fix it. I tried to get review by Eric, but failed.

diff --git a/sys/dev/drm/i915_dma.c b/sys/dev/drm/i915_dma.c
index 16955bd..69854b4 100644
--- a/sys/dev/drm/i915_dma.c
+++ b/sys/dev/drm/i915_dma.c
@@ -366,20 +366,14 @@ static int i915_emit_cmds(drm_device_t * dev, int __u=
ser * buffer, int dwords)
 	for (i =3D 0; i < dwords;) {
 		int cmd, sz;
=20
-	     if (DRM_COPY_FROM_USER_UNCHECKED(&cmd, &buffer[i], sizeof(cmd))) {
-
-			return DRM_ERR(EINVAL);
-	      }
+		cmd =3D buffer[i];
 		if ((sz =3D validate_cmd(cmd)) =3D=3D 0 || i + sz > dwords)
 			return DRM_ERR(EINVAL);
=20
 		OUT_RING(cmd);
=20
 		while (++i, --sz) {
-			if (DRM_COPY_FROM_USER_UNCHECKED(&cmd, &buffer[i],
-							 sizeof(cmd))) {
-				return DRM_ERR(EINVAL);
-			}
+			cmd =3D buffer[i];
 			OUT_RING(cmd);
 		}
 	}
@@ -400,10 +394,7 @@ static int i915_emit_box(drm_device_t * dev,
 	drm_clip_rect_t box;
 	RING_LOCALS;
=20
-	if (DRM_COPY_FROM_USER_UNCHECKED(&box, &boxes[i], sizeof(box))) {
-		return EFAULT;
-	}
-
+	box =3D boxes[i];
 	if (box.y2 <=3D box.y1 || box.x2 <=3D box.x1 || box.y2 <=3D 0 || box.x2 <=
=3D 0) {
 		DRM_ERROR("Bad box %d,%d..%d,%d\n",
 			  box.x1, box.y1, box.x2, box.y2);
@@ -603,6 +594,7 @@ static int i915_batchbuffer(DRM_IOCTL_ARGS)
 	drm_i915_sarea_t *sarea_priv =3D (drm_i915_sarea_t *)
 	    dev_priv->sarea_priv;
 	drm_i915_batchbuffer_t batch;
+	size_t cliplen;
 	int ret;
=20
 	if (!dev_priv->allow_batchbuffer) {
@@ -618,14 +610,25 @@ static int i915_batchbuffer(DRM_IOCTL_ARGS)
=20
 	LOCK_TEST_WITH_RETURN(dev, filp);
=20
+	DRM_UNLOCK();
+	cliplen =3D batch.num_cliprects * sizeof(drm_clip_rect_t);=09
 	if (batch.num_cliprects && DRM_VERIFYAREA_READ(batch.cliprects,
-						       batch.num_cliprects *
-						       sizeof(drm_clip_rect_t)))
+						       cliplen)) {
+		DRM_LOCK();
 		return DRM_ERR(EFAULT);
-
+	}
+	ret =3D vslock(batch.cliprects, cliplen);
+	if (ret) {
+		DRM_ERROR("Fault wiring cliprects\n");
+		DRM_LOCK();
+		return DRM_ERR(EFAULT);
+	}
+	DRM_LOCK();
 	ret =3D i915_dispatch_batchbuffer(dev, &batch);
-
 	sarea_priv->last_dispatch =3D (int)hw_status[5];
+	DRM_UNLOCK();
+	vsunlock(batch.cliprects, cliplen);
+	DRM_LOCK();
 	return ret;
 }
=20
@@ -637,6 +640,7 @@ static int i915_cmdbuffer(DRM_IOCTL_ARGS)
 	drm_i915_sarea_t *sarea_priv =3D (drm_i915_sarea_t *)
 	    dev_priv->sarea_priv;
 	drm_i915_cmdbuffer_t cmdbuf;
+	size_t cliplen;
 	int ret;
=20
 	DRM_COPY_FROM_USER_IOCTL(cmdbuf, (drm_i915_cmdbuffer_t __user *) data,
@@ -647,22 +651,38 @@ static int i915_cmdbuffer(DRM_IOCTL_ARGS)
=20
 	LOCK_TEST_WITH_RETURN(dev, filp);
=20
+	DRM_UNLOCK();
+	cliplen =3D cmdbuf.num_cliprects * sizeof(drm_clip_rect_t);
 	if (cmdbuf.num_cliprects &&
-	    DRM_VERIFYAREA_READ(cmdbuf.cliprects,
-				cmdbuf.num_cliprects *
-				sizeof(drm_clip_rect_t))) {
+	    DRM_VERIFYAREA_READ(cmdbuf.cliprects, cliplen)) {
 		DRM_ERROR("Fault accessing cliprects\n");
+		DRM_LOCK();
 		return DRM_ERR(EFAULT);
 	}
-
-	ret =3D i915_dispatch_cmdbuffer(dev, &cmdbuf);
+	ret =3D vslock(cmdbuf.cliprects, cliplen);
 	if (ret) {
-		DRM_ERROR("i915_dispatch_cmdbuffer failed\n");
-		return ret;
+		DRM_ERROR("Fault wiring cliprects\n");
+		DRM_LOCK();
+		return DRM_ERR(EFAULT);
 	}
-
-	sarea_priv->last_dispatch =3D (int)hw_status[5];
-	return 0;
+	ret =3D vslock(cmdbuf.buf, cmdbuf.sz);
+	if (ret) {
+		vsunlock(cmdbuf.cliprects, cliplen);
+		DRM_ERROR("Fault wiring cmds\n");
+		DRM_LOCK();
+		return DRM_ERR(EFAULT);
+	}
+	DRM_LOCK();
+	ret =3D i915_dispatch_cmdbuffer(dev, &cmdbuf);
+	if (ret =3D=3D 0)
+		sarea_priv->last_dispatch =3D (int)hw_status[5];
+	else
+		DRM_ERROR("i915_dispatch_cmdbuffer failed\n");
+	DRM_UNLOCK();
+	vsunlock(cmdbuf.buf, cmdbuf.sz);
+	vsunlock(cmdbuf.cliprects, cliplen);
+	DRM_LOCK();
+	return (ret);
 }
=20
 static int i915_do_cleanup_pageflip(drm_device_t * dev)

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