[Mesa-dev] [PATCH] vulkan/wsi: Avoid waiting indefinitely for present completion in x11_manage_fifo_queues().

[Henri Verbeet]

In particular, if the window was destroyed before the present request
completed, xcb_wait_for_special_event() may never return.

Note that the usage of xcb_poll_for_special_event() requires a version
of libxcb that includes commit fad81b63422105f9345215ab2716c4b804ec7986
to work properly.

Signed-off-by: Henri Verbeet <hverbeet at gmail.com>
---
This applies on top of "vulkan/wsi: Free the event in x11_manage_fifo_queues()."
---
 src/vulkan/wsi/wsi_common_x11.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/vulkan/wsi/wsi_common_x11.c b/src/vulkan/wsi/wsi_common_x11.c
index 22b067b..ceb0d66 100644
--- a/src/vulkan/wsi/wsi_common_x11.c
+++ b/src/vulkan/wsi/wsi_common_x11.c
@@ -908,10 +908,14 @@ static void *
 x11_manage_fifo_queues(void *state)
 {
    struct x11_swapchain *chain = state;
+   struct pollfd pfds;
    VkResult result;
 
    assert(chain->base.present_mode == VK_PRESENT_MODE_FIFO_KHR);
 
+   pfds.fd = xcb_get_file_descriptor(chain->conn);
+   pfds.events = POLLIN;
+
    while (chain->status == VK_SUCCESS) {
       /* It should be safe to unconditionally block here.  Later in the loop
        * we blocks until the previous present has landed on-screen.  At that
@@ -934,9 +938,18 @@ x11_manage_fifo_queues(void *state)
 
       while (chain->last_present_msc < target_msc) {
          xcb_generic_event_t *event =
-            xcb_wait_for_special_event(chain->conn, chain->special_event);
-         if (!event)
-            goto fail;
+            xcb_poll_for_special_event(chain->conn, chain->special_event);
+         if (!event) {
+            int ret = poll(&pfds, 1, 100);
+            if (ret < 0) {
+               result = VK_ERROR_OUT_OF_DATE_KHR;
+               goto fail;
+            } else if (chain->status != VK_SUCCESS) {
+               return NULL;
+            }
+
+            continue;
+         }
 
          result = x11_handle_dri3_present_event(chain, (void *)event);
          free(event);
-- 
2.1.4