[Mesa-dev] [PATCH 2/2] st/wgl: flush with ST_FLUSH_WAIT before releasing shared contexts

[Charmaine Lee]

Before releasing a shared context, flush the context
with ST_FLUSH_WAIT to make sure all commands are executed.
This ensures that rendering to any shared resources is completed
before they will be referenced by another context.

Fixes an intermittent flickering with Photoshop. (VMware bug# 1779340)
---
 src/gallium/state_trackers/wgl/stw_context.c | 16 ++++++++++++++--
 src/gallium/state_trackers/wgl/stw_context.h |  1 +
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/gallium/state_trackers/wgl/stw_context.c b/src/gallium/state_trackers/wgl/stw_context.c
index b1e5f5e..85cffa6 100644
--- a/src/gallium/state_trackers/wgl/stw_context.c
+++ b/src/gallium/state_trackers/wgl/stw_context.c
@@ -104,8 +104,11 @@ DrvShareLists(DHGLRC dhglrc1, DHGLRC dhglrc2)
    ctx1 = stw_lookup_context_locked( dhglrc1 );
    ctx2 = stw_lookup_context_locked( dhglrc2 );
 
-   if (ctx1 && ctx2 && ctx2->st->share)
+   if (ctx1 && ctx2 && ctx2->st->share) {
       ret = ctx2->st->share(ctx2->st, ctx1->st);
+      ctx1->shared = TRUE;
+      ctx2->shared = TRUE;
+   }
 
    stw_unlock_contexts(stw_dev);
 
@@ -175,6 +178,7 @@ stw_create_context_attribs(HDC hdc, INT iLayerPlane, DHGLRC hShareContext,
    if (hShareContext != 0) {
       stw_lock_contexts(stw_dev);
       shareCtx = stw_lookup_context_locked( hShareContext );
+      shareCtx->shared = TRUE;
       stw_unlock_contexts(stw_dev);
    }
 
@@ -184,6 +188,7 @@ stw_create_context_attribs(HDC hdc, INT iLayerPlane, DHGLRC hShareContext,
 
    ctx->hdc = hdc;
    ctx->iPixelFormat = iPixelFormat;
+   ctx->shared = shareCtx != NULL;
 
    memset(&attribs, 0, sizeof(attribs));
    attribs.visual = pfi->stvis;
@@ -403,7 +408,14 @@ stw_make_current(HDC hdc, DHGLRC dhglrc)
             return TRUE;
          }
       } else {
-         old_ctx->st->flush(old_ctx->st, ST_FLUSH_FRONT, NULL);
+         if (old_ctx->shared) {
+            struct pipe_fence_handle *fence = NULL;
+            old_ctx->st->flush(old_ctx->st,
+                               ST_FLUSH_FRONT | ST_FLUSH_WAIT, &fence);
+         }
+         else {
+            old_ctx->st->flush(old_ctx->st, ST_FLUSH_FRONT, NULL);
+         }
       }
    }
 
diff --git a/src/gallium/state_trackers/wgl/stw_context.h b/src/gallium/state_trackers/wgl/stw_context.h
index 6bfa715..0f180c8 100644
--- a/src/gallium/state_trackers/wgl/stw_context.h
+++ b/src/gallium/state_trackers/wgl/stw_context.h
@@ -40,6 +40,7 @@ struct stw_context
    DHGLRC dhglrc;
    int iPixelFormat;
    HDC hdc;
+   BOOL shared;
 
    struct stw_framebuffer *current_framebuffer;
 
-- 
1.9.1