[PULL 21/24] virtio-gpu: avoid re-entering cmdq processing

[Gerd Hoffmann <kraxel@redhat.com>]

From: Marc-André Lureau <marcandre.lureau@redhat.com>

The next patch will notify the GL context got flush, which will resume
the queue processing. However, if this happens within the caller
context, it will end up with a stack overflow flush/update loop.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20210204105232.834642-18-marcandre.lureau@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 include/hw/virtio/virtio-gpu.h | 1 +
 hw/display/virtio-gpu.c        | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
index 4f3dbf79f9bc..0043268e9021 100644
--- a/include/hw/virtio/virtio-gpu.h
+++ b/include/hw/virtio/virtio-gpu.h
@@ -148,6 +148,7 @@ struct VirtIOGPU {
 
     uint64_t hostmem;
 
+    bool processing_cmdq;
     bool renderer_inited;
     bool renderer_reset;
     QEMUTimer *fence_poll;
diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
index 0e833a462bae..7eb4265a6da7 100644
--- a/hw/display/virtio-gpu.c
+++ b/hw/display/virtio-gpu.c
@@ -814,6 +814,10 @@ void virtio_gpu_process_cmdq(VirtIOGPU *g)
 {
     struct virtio_gpu_ctrl_command *cmd;
 
+    if (g->processing_cmdq) {
+        return;
+    }
+    g->processing_cmdq = true;
     while (!QTAILQ_EMPTY(&g->cmdq)) {
         cmd = QTAILQ_FIRST(&g->cmdq);
 
@@ -843,6 +847,7 @@ void virtio_gpu_process_cmdq(VirtIOGPU *g)
             g_free(cmd);
         }
     }
+    g->processing_cmdq = false;
 }
 
 static void virtio_gpu_gl_unblock(VirtIOGPUBase *b)
-- 
2.29.2