From: Marcin Slusarz Date: Sun, 25 Sep 2011 14:01:19 +0000 (+0200) Subject: nouveau: fix crash during fence emission X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=65b8eea0644fdb7e9150d0e98c06d7f8ba6d5302;p=mesa.git nouveau: fix crash during fence emission Fence emission can flush the push buffer, which through flush_notify unreferences recently emitted fence. If ref count is increased after fence emission, unreference deletes the fence, which causes SIGSEGV. Backtrace: nouveau_fence_del nouveau_fence_ref nouveau_fence_next nouveau_pushbuf_flush MARK_RING nv50_screen_fence_emit nouveau_fence_emit nv50_flush This bug manifested as an assertion failure in nouveau_fence.c, because SIGSEGV handler tried to shutdown the application and used messed up fence. This issue was reported by Maxim Levitsky. Note: This is a candidate for the 7.11 branch. --- diff --git a/src/gallium/drivers/nouveau/nouveau_fence.c b/src/gallium/drivers/nouveau/nouveau_fence.c index ea2038cc7e2..26e4775b12d 100644 --- a/src/gallium/drivers/nouveau/nouveau_fence.c +++ b/src/gallium/drivers/nouveau/nouveau_fence.c @@ -93,8 +93,6 @@ nouveau_fence_emit(struct nouveau_fence *fence) /* set this now, so that if fence.emit triggers a flush we don't recurse */ fence->state = NOUVEAU_FENCE_STATE_EMITTED; - screen->fence.emit(&screen->base, fence->sequence); - ++fence->ref; if (screen->fence.tail) @@ -103,6 +101,8 @@ nouveau_fence_emit(struct nouveau_fence *fence) screen->fence.head = fence; screen->fence.tail = fence; + + screen->fence.emit(&screen->base, fence->sequence); } void