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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2013-03-01 04:43:13 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-03-01 04:43:13 +0100 |
| commit | 5e04f4b4290e03deb91b074087ae8d7c169d947d (patch) | |
| tree | 07802848a6afce236de7c3185be06db8567b38f0 /Documentation | |
| parent | Merge branch 'for-3.9' of git://linux-nfs.org/~bfields/linux (diff) | |
| parent | CHROMIUM: dma-buf: restore args on failure of dma_buf_mmap (diff) | |
| download | linux-5e04f4b4290e03deb91b074087ae8d7c169d947d.tar.xz linux-5e04f4b4290e03deb91b074087ae8d7c169d947d.zip | |
Merge tag 'tag-for-linus-3.9' of git://git.linaro.org/people/sumitsemwal/linux-dma-buf
Pull dma-buf framework updates from Sumit Semwal:
"Refcounting implemented for vmap in core dma-buf"
* tag 'tag-for-linus-3.9' of git://git.linaro.org/people/sumitsemwal/linux-dma-buf:
CHROMIUM: dma-buf: restore args on failure of dma_buf_mmap
dma-buf: implement vmap refcounting in the interface logic
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/dma-buf-sharing.txt | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/Documentation/dma-buf-sharing.txt b/Documentation/dma-buf-sharing.txt index 0188903bc9e1..4966b1be42ac 100644 --- a/Documentation/dma-buf-sharing.txt +++ b/Documentation/dma-buf-sharing.txt @@ -302,7 +302,11 @@ Access to a dma_buf from the kernel context involves three steps: void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr) The vmap call can fail if there is no vmap support in the exporter, or if it - runs out of vmalloc space. Fallback to kmap should be implemented. + runs out of vmalloc space. Fallback to kmap should be implemented. Note that + the dma-buf layer keeps a reference count for all vmap access and calls down + into the exporter's vmap function only when no vmapping exists, and only + unmaps it once. Protection against concurrent vmap/vunmap calls is provided + by taking the dma_buf->lock mutex. 3. Finish access |