xf86-video-intel: src/sna/sna_composite.c

[GitLab Mirror]

 src/sna/sna_composite.c |   21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

New commits:
commit 9236c58252511d3e985cbd4c022a202c36314e3c
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Thu Nov 26 20:15:58 2020 +0000

    sna: Defer fbGetWindowPixmap() for sna_composite
    
    Mike Lothian ran into a surprising situation where compScreenUpdate was
    calling CompositePicture without a pixmap attached to the destination
    Window, and so we found ourselves chasing a NULL PixmapPtr.
    
      #1  to_sna_from_pixmap (pixmap=0x0) at sna.h:521
      #2  sna_composite (op=<optimized out>, src=0x55b3346c1420, mask=0x0,
          dst=0x55b3346c1d50, src_x=<optimized out>, src_y=<optimized out>, mask_x=0,
          mask_y=0, dst_x=0, dst_y=0, width=3840, height=2160) at sna_composite.c:652
      #3  0x000055b33202c208 in damageComposite (op=<optimized out>,
          pSrc=0x55b3346c1420, pMask=0x0, pDst=0x55b3346c1d50, xSrc=<optimized out>,
          ySrc=<optimized out>, xMask=0, yMask=0, xDst=0, yDst=0, width=3840,
          height=2160) at damage.c:513
      #4  0x000055b33201820c in CompositePicture (op=<optimized out>,
          op at entry=1 '\001', pSrc=pSrc at entry=0x55b3346c1420, pMask=pMask at entry=0x0,
          pDst=pDst at entry=0x55b3346c1d50, xSrc=xSrc at entry=0, ySrc=ySrc at entry=0,
          xMask=0, yMask=0, xDst=0, yDst=0, width=3840, height=2160) at picture.c:1547
      #5  0x000055b331fc85d3 in compWindowUpdateAutomatic (
          pWin=pWin at entry=0x55b3343a6bc0) at compwindow.c:705
      #6  0x000055b331fca029 in compPaintWindowToParent (pWin=pWin at entry=0x55b3343a6bc0)
          at compwindow.c:729
      #7  0x000055b331fc9fbb in compPaintChildrenToWindow (pWin=0x55b333e77b50)
          at compwindow.c:744
      #8  0x000055b331fca59f in compScreenUpdate (pClient=<optimized out>,
          closure=<optimized out>) at compalloc.c:57
      #9  0x000055b331f3abf4 in ProcessWorkQueue () at dixutils.c:536
      #10 0x000055b3320aaa51 in WaitForSomething (are_ready=<optimized out>)
          at WaitFor.c:192
      #11 0x000055b331f361a9 in Dispatch () at dispatch.c:421
      #12 0x000055b331f39cec in dix_main (argc=13, argv=0x7ffcf273f538,
          envp=<optimized out>) at main.c:276
      #13 0x000055b331f247de in main (argc=<optimized out>, argv=<optimized out>,
          envp=<optimized out>) at stubmain.c:34
    
    Fortuitously, that drawable was also fully clipped so that it took an
    early exit and so we can hide the segfault by delaying querying the
    pixmap until after the clip check.
    
    The ongoing mystery is how we ended up in that state in the first place.
    
    Closes: https://gitlab.freedesktop.org/xorg/driver/xf86-video-intel/-/issues/204
    Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

diff --git a/src/sna/sna_composite.c b/src/sna/sna_composite.c
index 3a8e8684..f7a44d56 100644
--- a/src/sna/sna_composite.c
+++ b/src/sna/sna_composite.c
@@ -649,15 +649,15 @@ sna_composite(CARD8 op,
 	      CARD16 width, CARD16 height)
 {
 	PixmapPtr pixmap = get_drawable_pixmap(dst->pDrawable);
-	struct sna *sna = to_sna_from_pixmap(pixmap);
 	struct sna_pixmap *priv;
 	struct sna_composite_op tmp;
 	RegionRec region;
+	struct sna *sna;
 	int dx, dy;
 
 	DBG(("%s(pixmap=%ld, op=%d, src=%ld+(%d, %d), mask=%ld+(%d, %d), dst=%ld+(%d, %d)+(%d, %d), size=(%d, %d)\n",
 	     __FUNCTION__,
-	     pixmap->drawable.serialNumber, op,
+	     pixmap ? pixmap->drawable.serialNumber : 0, op,
 	     get_picture_id(src), src_x, src_y,
 	     get_picture_id(mask), mask_x, mask_y,
 	     get_picture_id(dst), dst_x, dst_y,
@@ -672,8 +672,7 @@ sna_composite(CARD8 op,
 	if (op == PictOpClear) {
 		DBG(("%s: discarding source and mask for clear\n", __FUNCTION__));
 		mask = NULL;
-		if (sna->clear)
-			src = sna->clear;
+		src = NULL;
 	}
 
 	if (!sna_compute_composite_region(&region,
@@ -694,11 +693,6 @@ sna_composite(CARD8 op,
 	if (NO_COMPOSITE)
 		goto fallback;
 
-	if (wedged(sna)) {
-		DBG(("%s: fallback -- wedged\n", __FUNCTION__));
-		goto fallback;
-	}
-
 	if (!can_render_to_picture(dst)) {
 		DBG(("%s: fallback due to unhandled picture\n", __FUNCTION__));
 		goto fallback;
@@ -711,6 +705,15 @@ sna_composite(CARD8 op,
 		goto fallback;
 	}
 
+	sna = to_sna_from_pixmap(pixmap);
+	if (wedged(sna)) {
+		DBG(("%s: fallback -- wedged\n", __FUNCTION__));
+		goto fallback;
+	}
+
+	if (op == PictOpClear)
+		src = sna->clear;
+
 	if (use_cpu(pixmap, priv, op, width, height) &&
 	    !picture_is_gpu(sna, src, PREFER_GPU_RENDER) &&
 	    !picture_is_gpu(sna, mask, PREFER_GPU_RENDER)) {