From: Chris Wilson Date: Mon, 15 Aug 2016 15:42:18 +0000 (+0100) Subject: dma-buf: Wait on the reservation object when sync'ing before CPU access X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=ae4e46b14bd7a12fb7908425846be7ceb0853bbc;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git dma-buf: Wait on the reservation object when sync'ing before CPU access Rendering operations to the dma-buf are tracked implicitly via the reservation_object (dmabuf->resv). This is used to allow poll() to wait upon outstanding rendering (or just query the current status of rendering). The dma-buf sync ioctl allows userspace to prepare the dma-buf for CPU access, which should include waiting upon rendering. (Some drivers may need to do more work to ensure that the dma-buf mmap is coherent as well as complete.) v2: Always wait upon the reservation object implicitly. We choose to do it after the native handler in case it can do so more efficiently. Testcase: igt/prime_vgem Testcase: igt/gem_concurrent_blit # *vgem* Signed-off-by: Chris Wilson Cc: Sumit Semwal Cc: Daniel Vetter Cc: Eric Anholt Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: linux-kernel@vger.kernel.org Reviewed-by: Daniel Vetter Signed-off-by: Sumit Semwal Link: http://patchwork.freedesktop.org/patch/msgid/1471275738-31994-1-git-send-email-chris@chris-wilson.co.uk --- diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index ddaee60ae52a..cf04d249a6a4 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -586,6 +586,22 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, } EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment); +static int __dma_buf_begin_cpu_access(struct dma_buf *dmabuf, + enum dma_data_direction direction) +{ + bool write = (direction == DMA_BIDIRECTIONAL || + direction == DMA_TO_DEVICE); + struct reservation_object *resv = dmabuf->resv; + long ret; + + /* Wait on any implicit rendering fences */ + ret = reservation_object_wait_timeout_rcu(resv, write, true, + MAX_SCHEDULE_TIMEOUT); + if (ret < 0) + return ret; + + return 0; +} /** * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the @@ -608,6 +624,13 @@ int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, if (dmabuf->ops->begin_cpu_access) ret = dmabuf->ops->begin_cpu_access(dmabuf, direction); + /* Ensure that all fences are waited upon - but we first allow + * the native handler the chance to do so more efficiently if it + * chooses. A double invocation here will be reasonably cheap no-op. + */ + if (ret == 0) + ret = __dma_buf_begin_cpu_access(dmabuf, direction); + return ret; } EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);