uxa: Review uxa_prepare_access() to remove potential nesting

Around a call to uxa_put_image() it is possible to mix both accelerated
and fallback paths, with the fallback code making the presumed
optimisation of only trying to call uxa_prepare_access() once. This
fails if the accelerated path also uses prepare/finish access on the
same drawable and then later fallback to the fallback path. This can
happen currently if an error is reported whilst attempting to accelerate
PutImage.

  #0  memcpy () at ../sysdeps/x86_64/memcpy.S:162
  #1  0x00007ffff43ce4bd in fbBlt (srcLine=<value optimized out>, srcStride=40, srcX=<value optimized out>, dstLine=0xffffffffffffffff, dstStride=64, dstX=0, width=<value optimized out>, height=8, alu=3, pm=4294967295, bpp=8, reverse=0, upsidedown=0) at fbblt.c:93
  #2  0x00007ffff43ce740 in fbBltStip (src=0xffffffffffffffff, srcStride=156555204, srcX=34, dst=0xfffffffc, dstStride=64, dstX=40, width=304, height=8, alu=3, pm=4294967295, bpp=8) at fbblt.c:944
  #3  0x00007ffff4c32c53 in uxa_do_put_image (pDrawable=0x246aa410, pGC=0x2c0a4f0, depth=8, x=0, y=0, w=38, h=8, leftPad=0, format=2, bits=0x954d7c4 "") at uxa-accel.c:196 #4  uxa_do_shm_put_image (pDrawable=0x246aa410, pGC=0x2c0a4f0, depth=8, x=0, y=0, w=38, h=8, leftPad=0, format=2, bits=0x954d7c4 "") at uxa-accel.c:223
  #5  uxa_put_image (pDrawable=0x246aa410, pGC=0x2c0a4f0, depth=8, x=0, y=0, w=38, h=8, leftPad=0, format=2, bits=0x954d7c4 "") at uxa-accel.c:289
  #6  0x00000000004d574f in damagePutImage (pDrawable=0x246aa410, pGC=0x2c0a4f0, depth=8, x=0, y=0, w=38, h=8, leftPad=0, format=2, pImage=0x954d7c4 "") at damage.c:905
  #7  0x00000000004287db in ProcPutImage (client=0x47ca72d0) at dispatch.c:2073
  #8  0x000000000042bd94 in Dispatch () at dispatch.c:445
  #9  0x000000000042513a in main (argc=4, argv=0x7fffffffe2a8, envp=<value optimized out>) at main.c:285

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 8 insertions, 10 deletions

diff --git a/uxa/uxa-accel.c b/uxa/uxa-accel.c
index f0bf92f1..80be91f6 100644
--- a/uxa/uxa-accel.c
+++ b/uxa/uxa-accel.c
@@ -128,7 +128,6 @@ uxa_do_put_image(DrawablePtr pDrawable, GCPtr pGC, int depth, int x, int y,
 	int nbox;
 	int xoff, yoff;
 	int bpp = pDrawable->bitsPerPixel;
-	Bool access_prepared = FALSE;
 
 	/* Don't bother with under 8bpp, XYPixmaps. */
 	if (format != ZPixmap || bpp < 8)
@@ -183,12 +182,8 @@ uxa_do_put_image(DrawablePtr pDrawable, GCPtr pGC, int depth, int x, int y,
 			int dstBpp;
 			int dstXoff, dstYoff;
 
-			if (!access_prepared) {
-				if (!uxa_prepare_access
-				    (pDrawable, UXA_ACCESS_RW))
-					return FALSE;
-				access_prepared = TRUE;
-			}
+			if (!uxa_prepare_access(pDrawable, UXA_ACCESS_RW))
+				return FALSE;
 
 			fbGetStipDrawable(pDrawable, dst, dst_stride, dstBpp,
 					  dstXoff, dstYoff);
@@ -200,11 +195,11 @@ uxa_do_put_image(DrawablePtr pDrawable, GCPtr pGC, int depth, int x, int y,
 				  dst + (y1 + dstYoff) * dst_stride, dst_stride,
 				  (x1 + dstXoff) * dstBpp, (x2 - x1) * dstBpp,
 				  y2 - y1, GXcopy, FB_ALLONES, dstBpp);
+
+			uxa_finish_access(pDrawable);
 		}
 	}
 
-	if (access_prepared)
-		uxa_finish_access(pDrawable);
 
 	return TRUE;
 }
@@ -236,8 +231,11 @@ uxa_do_shm_put_image(DrawablePtr pDrawable, GCPtr pGC, int depth,
 		if (!pPixmap)
 			return FALSE;
 
-		if (!uxa_prepare_access(pDrawable, UXA_ACCESS_RW))
+		if (!uxa_prepare_access(pDrawable, UXA_ACCESS_RW)) {
+			FreeScratchPixmapHeader(pPixmap);
 			return FALSE;
+		}
+
 		fbCopyArea((DrawablePtr) pPixmap, pDrawable, pGC, sx, sy, sw,
 			   sh, dx, dy);
 		uxa_finish_access(pDrawable);