From d5d5f54fe9d9065c2476e520d8007c76f38b1839 Mon Sep 17 00:00:00 2001
From: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Date: Wed, 21 Feb 2024 16:31:10 -0500
Subject: [PATCH] zink: add a swapchain readback case for reading
 differently-acquired image

if a swapchain is shared between multiple resources, a deadlock and/or invalid
data will result from readback attempts if one resource holds a swapchain
image that the other resource must read from

to avoid this, allow accessing the acquiring resource directly since this is
the only sane way to perform readback

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/27553>
---
 src/gallium/drivers/zink/zink_kopper.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/gallium/drivers/zink/zink_kopper.c b/src/gallium/drivers/zink/zink_kopper.c
index a61720b18e0..b094aa4922b 100644
--- a/src/gallium/drivers/zink/zink_kopper.c
+++ b/src/gallium/drivers/zink/zink_kopper.c
@@ -873,6 +873,11 @@ zink_kopper_acquire_readback(struct zink_context *ctx, struct zink_resource *res
       *readback = res;
       return false;
    }
+   if (cswap->images[last_dt_idx].acquired) {
+      struct zink_resource *rb = cswap->images[last_dt_idx].acquired;
+      *readback = rb;
+      return false;
+   }
    if (cswap->images[last_dt_idx].readback) {
       struct zink_resource *rb = zink_resource(cswap->images[res->obj->last_dt_idx].readback);
       if (rb->valid) {