[Glamor] [PATCH 21/34] glamor: Allow nested mapping of pixmaps.

[Alex Deucher]

From: Eric Anholt <eric at anholt.net>

The common pattern is to do nested if statements making calls to
prepare_access() and then popping those mappings back off in each set
of braces. Some cases checked for src == dst to avoid leaking
mapping, but others didn't. Others didn't even do the nested
mappings, so a failure in the outer would result in trying to umap the
inner and failing.

By allowing nested mappings, we can fix both problems by not requiring
the care from the caller, plus we can allow a simpler nesting of all
the prepares in one if statement.

Ported from Eric's xserver glamor tree.

Signed-off-by: Eric Anholt <eric at anholt.net>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
---
 src/glamor_core.c | 20 +++++++++++++++++++-
 src/glamor_priv.h |  6 ++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/src/glamor_core.c b/src/glamor_core.c
index eb1a08d..33cbb72 100644
--- a/src/glamor_core.c
+++ b/src/glamor_core.c
@@ -107,6 +107,20 @@ Bool
 glamor_prepare_access(DrawablePtr drawable, glamor_access_t access)
 {
 	PixmapPtr pixmap = glamor_get_drawable_pixmap(drawable);
+	glamor_pixmap_private *pixmap_priv = glamor_get_pixmap_private(pixmap);
+
+	if (pixmap->devPrivate.ptr) {
+	    /* Already mapped, nothing needs to be done. Note that we
+	     * aren't allowing promotion from RO to RW, because it would
+	     * require re-mapping the PBO.
+	     */
+		assert(!GLAMOR_PIXMAP_PRIV_HAS_FBO(pixmap_priv) ||
+		       access == GLAMOR_ACCESS_RO ||
+		       pixmap_priv->base.mapped_for_write);
+		return TRUE;
+	}
+	pixmap_priv->base.mapped_for_write = (access == GLAMOR_ACCESS_RW);
+
 	return glamor_download_pixmap_to_cpu(pixmap, access);
 }
 
@@ -326,7 +340,11 @@ glamor_finish_access(DrawablePtr drawable, glamor_access_t access_mode)
 	if (!GLAMOR_PIXMAP_PRIV_HAS_FBO_DOWNLOADED(pixmap_priv))
 		return;
 
-	if (access_mode != GLAMOR_ACCESS_RO) {
+	/* If we are doing a series of unmaps from a nested map, we're done. */
+	if (!pixmap->devPrivate.ptr)
+	    return;
+
+	if (pixmap_priv->base.mapped_for_write) {
 		glamor_restore_pixmap_to_texture(pixmap);
 	}
 
diff --git a/src/glamor_priv.h b/src/glamor_priv.h
index 844bd7a..359604e 100644
--- a/src/glamor_priv.h
+++ b/src/glamor_priv.h
@@ -425,6 +425,12 @@ typedef struct glamor_pixmap_clipped_regions{
 typedef struct glamor_pixmap_private_base {
 	glamor_pixmap_type_t type;
 	enum glamor_fbo_state gl_fbo;
+	/**
+	 * If devPrivate.ptr is non-NULL (meaning we're within
+	 * glamor_prepare_access), determies whether we should re-upload
+	 * that data on glamor_finish_access().
+	 */
+	Bool mapped_for_write;
 	unsigned char is_picture:1;
 	unsigned char gl_tex:1;
 	glamor_pixmap_fbo *fbo;
-- 
1.8.3.1