From 09ea0dfbf972c63dfea8cf46f2fb67f39e4d833b Mon Sep 17 00:00:00 2001 From: Gerd Hoffmann Date: Tue, 29 May 2018 15:59:18 +0200 Subject: [PATCH] dma-buf: make map_atomic and map function pointers optional So drivers don't need dummy functions just returning NULL. Cc: Daniel Vetter Signed-off-by: Gerd Hoffmann Reviewed-by: Daniel Vetter Reviewed-by: Oleksandr Andrushchenko Link: http://patchwork.freedesktop.org/patch/msgid/20180529135918.19729-1-kraxel@redhat.com --- drivers/dma-buf/dma-buf.c | 4 ++++ include/linux/dma-buf.h | 4 ++-- 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index d78d5fc173dc..4c45e31258f0 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -872,6 +872,8 @@ void *dma_buf_kmap_atomic(struct dma_buf *dmabuf, unsigned long page_num) { WARN_ON(!dmabuf); + if (!dmabuf->ops->map_atomic) + return NULL; return dmabuf->ops->map_atomic(dmabuf, page_num); } EXPORT_SYMBOL_GPL(dma_buf_kmap_atomic); @@ -907,6 +909,8 @@ void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num) { WARN_ON(!dmabuf); + if (!dmabuf->ops->map) + return NULL; return dmabuf->ops->map(dmabuf, page_num); } EXPORT_SYMBOL_GPL(dma_buf_kmap); diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 085db2fee2d7..88917fa796e4 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -39,12 +39,12 @@ struct dma_buf_attachment; /** * struct dma_buf_ops - operations possible on struct dma_buf - * @map_atomic: maps a page from the buffer into kernel address + * @map_atomic: [optional] maps a page from the buffer into kernel address * space, users may not block until the subsequent unmap call. * This callback must not sleep. * @unmap_atomic: [optional] unmaps a atomically mapped page from the buffer. * This Callback must not sleep. - * @map: maps a page from the buffer into kernel address space. + * @map: [optional] maps a page from the buffer into kernel address space. * @unmap: [optional] unmaps a page from the buffer. * @vmap: [optional] creates a virtual mapping for the buffer into kernel * address space. Same restrictions as for vmap and friends apply. -- 2.11.0