From c9ffe51538e699d6a110ef73ce8ff2b906fd7e44 Mon Sep 17 00:00:00 2001 From: jsg Date: Mon, 4 Mar 2024 02:37:13 +0000 Subject: [PATCH] drm/syncobj: handle NULL fence in syncobj_eventfd_entry_func From Erik Kurzinger 20e1e1a2b8a4525301a76bd9afb856a7606a3a34 in linux-6.6.y/6.6.19 2aa6f5b0fd052e363bb9d4b547189f0bf6b3d6d3 in mainline linux --- sys/dev/pci/drm/drm_syncobj.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/sys/dev/pci/drm/drm_syncobj.c b/sys/dev/pci/drm/drm_syncobj.c index 9d722d5d6a6..841bc90810e 100644 --- a/sys/dev/pci/drm/drm_syncobj.c +++ b/sys/dev/pci/drm/drm_syncobj.c @@ -1446,10 +1446,21 @@ syncobj_eventfd_entry_func(struct drm_syncobj *syncobj, /* This happens inside the syncobj lock */ fence = dma_fence_get(rcu_dereference_protected(syncobj->fence, 1)); + if (!fence) + return; + ret = dma_fence_chain_find_seqno(&fence, entry->point); - if (ret != 0 || !fence) { + if (ret != 0) { + /* The given seqno has not been submitted yet. */ dma_fence_put(fence); return; + } else if (!fence) { + /* If dma_fence_chain_find_seqno returns 0 but sets the fence + * to NULL, it implies that the given seqno is signaled and a + * later seqno has already been submitted. Assign a stub fence + * so that the eventfd still gets signaled below. + */ + fence = dma_fence_get_stub(); } list_del_init(&entry->node); -- 2.20.1