From f00b4dad9d9eb001a04cf72e8351a2a1b9e99322 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Thu, 20 Dec 2012 14:14:23 +0100 Subject: dma-buf: implement vmap refcounting in the interface logic All drivers which implement this need to have some sort of refcount to allow concurrent vmap usage. Hence implement this in the dma-buf core. To protect against concurrent calls we need a lock, which potentially causes new funny locking inversions. But this shouldn't be a problem for exporters with statically allocated backing storage, and more dynamic drivers have decent issues already anyway. Inspired by some refactoring patches from Aaron Plattner, who implemented the same idea, but only for drm/prime drivers. v2: Check in dma_buf_release that no dangling vmaps are left. Suggested by Aaron Plattner. We might want to do similar checks for attachments, but that's for another patch. Also fix up ERR_PTR return for vmap. v3: Check whether the passed-in vmap address matches with the cached one for vunmap. Eventually we might want to remove that parameter - compared to the kmap functions there's no need for the vaddr for unmapping. Suggested by Chris Wilson. v4: Fix a brown-paper-bag bug spotted by Aaron Plattner. Cc: Aaron Plattner Reviewed-by: Aaron Plattner Tested-by: Aaron Plattner Reviewed-by: Rob Clark Signed-off-by: Daniel Vetter Signed-off-by: Sumit Semwal --- include/linux/dma-buf.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include/linux/dma-buf.h') diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 3d754a394e92..9978b614a1aa 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -119,8 +119,10 @@ struct dma_buf { struct file *file; struct list_head attachments; const struct dma_buf_ops *ops; - /* mutex to serialize list manipulation and attach/detach */ + /* mutex to serialize list manipulation, attach/detach and vmap/unmap */ struct mutex lock; + unsigned vmapping_counter; + void *vmap_ptr; void *priv; }; -- cgit v1.2.3-59-g8ed1b