Move deferred vblank events to separate drm_vblank_deferred list

It was still possible for nested xorg_list_for_each_entry_safe loops
to occur over the drm_vblank_signalled list, which could mess up that
list. Moving deferred events to a separate list allows processing the
drm_vblank_signalled list without xorg_list_for_each_entry_safe.

v2:
* Refactor drm_handle_vblank_signalled helper function, less code
  duplication => better readability (Alex Deucher)

Bugzilla: https://bugs.freedesktop.org/108600
Acked-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 46 insertions, 11 deletions

diff --git a/src/amdgpu_drm_queue.c b/src/amdgpu_drm_queue.c
index 808941b..56d593d 100644
--- a/src/amdgpu_drm_queue.c
+++ b/src/amdgpu_drm_queue.c
@@ -56,6 +56,7 @@ static int amdgpu_drm_queue_refcnt;
 static struct xorg_list amdgpu_drm_queue;
 static struct xorg_list amdgpu_drm_flip_signalled;
 static struct xorg_list amdgpu_drm_vblank_signalled;
+static struct xorg_list amdgpu_drm_vblank_deferred;
 static uintptr_t amdgpu_drm_queue_seq;
 
 
@@ -112,6 +113,31 @@ amdgpu_drm_queue_handler(int fd, unsigned int frame, unsigned int sec,
 }
 
 /*
+ * Handle signalled vblank events. If we're waiting for a flip event,
+ * put events for that CRTC in the vblank_deferred list.
+ */
+static void
+amdgpu_drm_handle_vblank_signalled(void)
+{
+	drmmode_crtc_private_ptr drmmode_crtc;
+	struct amdgpu_drm_queue_entry *e;
+
+	while (!xorg_list_is_empty(&amdgpu_drm_vblank_signalled)) {
+		e = xorg_list_first_entry(&amdgpu_drm_vblank_signalled,
+					  struct amdgpu_drm_queue_entry, list);
+		drmmode_crtc = e->crtc->driver_private;
+
+		if (drmmode_crtc->wait_flip_nesting_level == 0) {
+			amdgpu_drm_queue_handle_one(e);
+			continue;
+		}
+
+		xorg_list_del(&e->list);
+		xorg_list_append(&e->list, &amdgpu_drm_vblank_deferred);
+	}
+}
+
+/*
  * Handle deferred DRM vblank events
  *
  * This function must be called after amdgpu_drm_wait_pending_flip, once
@@ -127,12 +153,18 @@ amdgpu_drm_queue_handle_deferred(xf86CrtcPtr crtc)
 	    --drmmode_crtc->wait_flip_nesting_level > 0)
 		return;
 
-	xorg_list_for_each_entry_safe(e, tmp, &amdgpu_drm_vblank_signalled, list) {
-		drmmode_crtc_private_ptr drmmode_crtc = e->crtc->driver_private;
+	/* Put previously deferred vblank events for this CRTC back in the
+	 * signalled queue
+	 */
+	xorg_list_for_each_entry_safe(e, tmp, &amdgpu_drm_vblank_deferred, list) {
+		if (e->crtc != crtc)
+			continue;
 
-		if (drmmode_crtc->wait_flip_nesting_level == 0)
-			amdgpu_drm_queue_handle_one(e);
+		xorg_list_del(&e->list);
+		xorg_list_append(&e->list, &amdgpu_drm_vblank_signalled);
 	}
+
+	amdgpu_drm_handle_vblank_signalled();
 }
 
 /*
@@ -205,6 +237,13 @@ amdgpu_drm_abort_entry(uintptr_t seq)
 		}
 	}
 
+	xorg_list_for_each_entry_safe(e, tmp, &amdgpu_drm_vblank_deferred, list) {
+		if (e->seq == seq) {
+			amdgpu_drm_abort_one(e);
+			return;
+		}
+	}
+
 	xorg_list_for_each_entry_safe(e, tmp, &amdgpu_drm_queue, list) {
 		if (e->seq == seq) {
 			amdgpu_drm_abort_one(e);
@@ -235,7 +274,7 @@ amdgpu_drm_abort_id(uint64_t id)
 int
 amdgpu_drm_handle_event(int fd, drmEventContext *event_context)
 {
-	struct amdgpu_drm_queue_entry *e, *tmp;
+	struct amdgpu_drm_queue_entry *e;
 	int r;
 
 	r = drmHandleEvent(fd, event_context);
@@ -246,12 +285,7 @@ amdgpu_drm_handle_event(int fd, drmEventContext *event_context)
 		amdgpu_drm_queue_handle_one(e);
 	}
 
-	xorg_list_for_each_entry_safe(e, tmp, &amdgpu_drm_vblank_signalled, list) {
-		drmmode_crtc_private_ptr drmmode_crtc = e->crtc->driver_private;
-
-		if (drmmode_crtc->wait_flip_nesting_level == 0)
-			amdgpu_drm_queue_handle_one(e);
-	}
+	amdgpu_drm_handle_vblank_signalled();
 
 	return r;
 }
@@ -298,6 +332,7 @@ amdgpu_drm_queue_init(ScrnInfoPtr scrn)
 	xorg_list_init(&amdgpu_drm_queue);
 	xorg_list_init(&amdgpu_drm_flip_signalled);
 	xorg_list_init(&amdgpu_drm_vblank_signalled);
+	xorg_list_init(&amdgpu_drm_vblank_deferred);
 }
 
 /*