From: Daniel Vetter Date: Thu, 20 Dec 2012 13:14:23 +0000 (+0100) Subject: dma-buf: implement vmap refcounting in the interface logic X-Git-Tag: v3.9-rc1~39^2~1 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f00b4dad9d9eb001a04cf72e8351a2a1b9e99322;p=pandora-kernel.git 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 --- Reading git-diff-tree failed