Merge branch 'for-linus-3.4' of git://git.linaro.org/people/sumitsemwal/linux-dma-buf
Pull dma-buf updates from Sumit Semwal: "This includes the following key items: - kernel cpu access support, - flag-passing to dma_buf_fd, - relevant Documentation updates, and - some minor cleanups and fixes. These changes are needed for the drm prime/dma-buf interface code that Dave Airlie plans to submit in this merge window." * 'for-linus-3.4' of git://git.linaro.org/people/sumitsemwal/linux-dma-buf: dma-buf: correct dummy function declarations. dma-buf: document fd flags and O_CLOEXEC requirement dma_buf: Add documentation for the new cpu access support dma-buf: add support for kernel cpu access dma-buf: don't hold the mutex around map/unmap calls dma-buf: add get_dma_buf() dma-buf: pass flags into dma_buf_fd. dma-buf: add dma_data_direction to unmap dma_buf_op dma-buf: Move code out of mutex-protected section in dma_buf_attach() dma-buf: Return error instead of using a goto statement when possible dma-buf: Remove unneeded sanity checks dma-buf: Constify ops argument to dma_buf_export()
This commit is contained in:
Linus Torvalds
commit
ed0bb8ea05
@ -32,8 +32,12 @@ The buffer-user
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*IMPORTANT*: [see https://lkml.org/lkml/2011/12/20/211 for more details]
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For this first version, A buffer shared using the dma_buf sharing API:
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- *may* be exported to user space using "mmap" *ONLY* by exporter, outside of
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this framework.
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- may be used *ONLY* by importers that do not need CPU access to the buffer.
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this framework.
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- with this new iteration of the dma-buf api cpu access from the kernel has been
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enable, see below for the details.
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dma-buf operations for device dma only
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--------------------------------------
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The dma_buf buffer sharing API usage contains the following steps:
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@ -219,10 +223,120 @@ NOTES:
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If the exporter chooses not to allow an attach() operation once a
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map_dma_buf() API has been called, it simply returns an error.
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Miscellaneous notes:
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Kernel cpu access to a dma-buf buffer object
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--------------------------------------------
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The motivation to allow cpu access from the kernel to a dma-buf object from the
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importers side are:
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- fallback operations, e.g. if the devices is connected to a usb bus and the
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kernel needs to shuffle the data around first before sending it away.
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- full transparency for existing users on the importer side, i.e. userspace
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should not notice the difference between a normal object from that subsystem
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and an imported one backed by a dma-buf. This is really important for drm
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opengl drivers that expect to still use all the existing upload/download
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paths.
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Access to a dma_buf from the kernel context involves three steps:
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1. Prepare access, which invalidate any necessary caches and make the object
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available for cpu access.
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2. Access the object page-by-page with the dma_buf map apis
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3. Finish access, which will flush any necessary cpu caches and free reserved
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resources.
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1. Prepare access
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Before an importer can access a dma_buf object with the cpu from the kernel
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context, it needs to notify the exporter of the access that is about to
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happen.
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Interface:
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int dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
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size_t start, size_t len,
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enum dma_data_direction direction)
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This allows the exporter to ensure that the memory is actually available for
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cpu access - the exporter might need to allocate or swap-in and pin the
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backing storage. The exporter also needs to ensure that cpu access is
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coherent for the given range and access direction. The range and access
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direction can be used by the exporter to optimize the cache flushing, i.e.
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access outside of the range or with a different direction (read instead of
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write) might return stale or even bogus data (e.g. when the exporter needs to
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copy the data to temporary storage).
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This step might fail, e.g. in oom conditions.
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2. Accessing the buffer
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To support dma_buf objects residing in highmem cpu access is page-based using
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an api similar to kmap. Accessing a dma_buf is done in aligned chunks of
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PAGE_SIZE size. Before accessing a chunk it needs to be mapped, which returns
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a pointer in kernel virtual address space. Afterwards the chunk needs to be
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unmapped again. There is no limit on how often a given chunk can be mapped
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and unmapped, i.e. the importer does not need to call begin_cpu_access again
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before mapping the same chunk again.
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Interfaces:
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void *dma_buf_kmap(struct dma_buf *, unsigned long);
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void dma_buf_kunmap(struct dma_buf *, unsigned long, void *);
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There are also atomic variants of these interfaces. Like for kmap they
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facilitate non-blocking fast-paths. Neither the importer nor the exporter (in
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the callback) is allowed to block when using these.
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Interfaces:
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void *dma_buf_kmap_atomic(struct dma_buf *, unsigned long);
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void dma_buf_kunmap_atomic(struct dma_buf *, unsigned long, void *);
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For importers all the restrictions of using kmap apply, like the limited
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supply of kmap_atomic slots. Hence an importer shall only hold onto at most 2
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atomic dma_buf kmaps at the same time (in any given process context).
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dma_buf kmap calls outside of the range specified in begin_cpu_access are
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undefined. If the range is not PAGE_SIZE aligned, kmap needs to succeed on
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the partial chunks at the beginning and end but may return stale or bogus
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data outside of the range (in these partial chunks).
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Note that these calls need to always succeed. The exporter needs to complete
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any preparations that might fail in begin_cpu_access.
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3. Finish access
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When the importer is done accessing the range specified in begin_cpu_access,
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it needs to announce this to the exporter (to facilitate cache flushing and
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unpinning of any pinned resources). The result of of any dma_buf kmap calls
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after end_cpu_access is undefined.
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Interface:
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void dma_buf_end_cpu_access(struct dma_buf *dma_buf,
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size_t start, size_t len,
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enum dma_data_direction dir);
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Miscellaneous notes
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-------------------
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- Any exporters or users of the dma-buf buffer sharing framework must have
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a 'select DMA_SHARED_BUFFER' in their respective Kconfigs.
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- In order to avoid fd leaks on exec, the FD_CLOEXEC flag must be set
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on the file descriptor. This is not just a resource leak, but a
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potential security hole. It could give the newly exec'd application
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access to buffers, via the leaked fd, to which it should otherwise
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not be permitted access.
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The problem with doing this via a separate fcntl() call, versus doing it
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atomically when the fd is created, is that this is inherently racy in a
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multi-threaded app[3]. The issue is made worse when it is library code
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opening/creating the file descriptor, as the application may not even be
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aware of the fd's.
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To avoid this problem, userspace must have a way to request O_CLOEXEC
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flag be set when the dma-buf fd is created. So any API provided by
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the exporting driver to create a dmabuf fd must provide a way to let
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userspace control setting of O_CLOEXEC flag passed in to dma_buf_fd().
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References:
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[1] struct dma_buf_ops in include/linux/dma-buf.h
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[2] All interfaces mentioned above defined in include/linux/dma-buf.h
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[3] https://lwn.net/Articles/236486/
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@ -71,7 +71,7 @@ static inline int is_dma_buf_file(struct file *file)
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* ops, or error in allocating struct dma_buf, will return negative error.
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*
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*/
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struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
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struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
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size_t size, int flags)
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{
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struct dma_buf *dmabuf;
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@ -80,7 +80,9 @@ struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
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if (WARN_ON(!priv || !ops
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|| !ops->map_dma_buf
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|| !ops->unmap_dma_buf
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|| !ops->release)) {
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|| !ops->release
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|| !ops->kmap_atomic
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|| !ops->kmap)) {
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return ERR_PTR(-EINVAL);
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}
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@ -107,17 +109,18 @@ EXPORT_SYMBOL_GPL(dma_buf_export);
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/**
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* dma_buf_fd - returns a file descriptor for the given dma_buf
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* @dmabuf: [in] pointer to dma_buf for which fd is required.
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* @flags: [in] flags to give to fd
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*
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* On success, returns an associated 'fd'. Else, returns error.
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*/
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int dma_buf_fd(struct dma_buf *dmabuf)
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int dma_buf_fd(struct dma_buf *dmabuf, int flags)
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{
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int error, fd;
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if (!dmabuf || !dmabuf->file)
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return -EINVAL;
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error = get_unused_fd();
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error = get_unused_fd_flags(flags);
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if (error < 0)
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return error;
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fd = error;
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@ -185,17 +188,18 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
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struct dma_buf_attachment *attach;
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int ret;
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if (WARN_ON(!dmabuf || !dev || !dmabuf->ops))
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if (WARN_ON(!dmabuf || !dev))
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return ERR_PTR(-EINVAL);
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attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
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if (attach == NULL)
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goto err_alloc;
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mutex_lock(&dmabuf->lock);
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return ERR_PTR(-ENOMEM);
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attach->dev = dev;
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attach->dmabuf = dmabuf;
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mutex_lock(&dmabuf->lock);
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if (dmabuf->ops->attach) {
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ret = dmabuf->ops->attach(dmabuf, dev, attach);
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if (ret)
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@ -206,8 +210,6 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
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mutex_unlock(&dmabuf->lock);
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return attach;
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err_alloc:
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return ERR_PTR(-ENOMEM);
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err_attach:
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kfree(attach);
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mutex_unlock(&dmabuf->lock);
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@ -224,7 +226,7 @@ EXPORT_SYMBOL_GPL(dma_buf_attach);
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*/
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void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
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{
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if (WARN_ON(!dmabuf || !attach || !dmabuf->ops))
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if (WARN_ON(!dmabuf || !attach))
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return;
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mutex_lock(&dmabuf->lock);
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@ -255,13 +257,10 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
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might_sleep();
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if (WARN_ON(!attach || !attach->dmabuf || !attach->dmabuf->ops))
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if (WARN_ON(!attach || !attach->dmabuf))
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return ERR_PTR(-EINVAL);
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mutex_lock(&attach->dmabuf->lock);
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if (attach->dmabuf->ops->map_dma_buf)
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sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
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mutex_unlock(&attach->dmabuf->lock);
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sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
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return sg_table;
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}
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@ -273,19 +272,137 @@ EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
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* dma_buf_ops.
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* @attach: [in] attachment to unmap buffer from
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* @sg_table: [in] scatterlist info of the buffer to unmap
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* @direction: [in] direction of DMA transfer
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*
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*/
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void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
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struct sg_table *sg_table)
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struct sg_table *sg_table,
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enum dma_data_direction direction)
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{
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if (WARN_ON(!attach || !attach->dmabuf || !sg_table
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|| !attach->dmabuf->ops))
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if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
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return;
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mutex_lock(&attach->dmabuf->lock);
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if (attach->dmabuf->ops->unmap_dma_buf)
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attach->dmabuf->ops->unmap_dma_buf(attach, sg_table);
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mutex_unlock(&attach->dmabuf->lock);
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attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
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direction);
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}
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EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
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/**
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* dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
|
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* cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific
|
||||
* preparations. Coherency is only guaranteed in the specified range for the
|
||||
* specified access direction.
|
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* @dma_buf: [in] buffer to prepare cpu access for.
|
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* @start: [in] start of range for cpu access.
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* @len: [in] length of range for cpu access.
|
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* @direction: [in] length of range for cpu access.
|
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*
|
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* Can return negative error values, returns 0 on success.
|
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*/
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int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
|
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enum dma_data_direction direction)
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{
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int ret = 0;
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|
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if (WARN_ON(!dmabuf))
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return -EINVAL;
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||||
|
||||
if (dmabuf->ops->begin_cpu_access)
|
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ret = dmabuf->ops->begin_cpu_access(dmabuf, start, len, direction);
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|
||||
return ret;
|
||||
}
|
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EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);
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|
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/**
|
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* dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
|
||||
* cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
|
||||
* actions. Coherency is only guaranteed in the specified range for the
|
||||
* specified access direction.
|
||||
* @dma_buf: [in] buffer to complete cpu access for.
|
||||
* @start: [in] start of range for cpu access.
|
||||
* @len: [in] length of range for cpu access.
|
||||
* @direction: [in] length of range for cpu access.
|
||||
*
|
||||
* This call must always succeed.
|
||||
*/
|
||||
void dma_buf_end_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
|
||||
enum dma_data_direction direction)
|
||||
{
|
||||
WARN_ON(!dmabuf);
|
||||
|
||||
if (dmabuf->ops->end_cpu_access)
|
||||
dmabuf->ops->end_cpu_access(dmabuf, start, len, direction);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
|
||||
|
||||
/**
|
||||
* dma_buf_kmap_atomic - Map a page of the buffer object into kernel address
|
||||
* space. The same restrictions as for kmap_atomic and friends apply.
|
||||
* @dma_buf: [in] buffer to map page from.
|
||||
* @page_num: [in] page in PAGE_SIZE units to map.
|
||||
*
|
||||
* This call must always succeed, any necessary preparations that might fail
|
||||
* need to be done in begin_cpu_access.
|
||||
*/
|
||||
void *dma_buf_kmap_atomic(struct dma_buf *dmabuf, unsigned long page_num)
|
||||
{
|
||||
WARN_ON(!dmabuf);
|
||||
|
||||
return dmabuf->ops->kmap_atomic(dmabuf, page_num);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(dma_buf_kmap_atomic);
|
||||
|
||||
/**
|
||||
* dma_buf_kunmap_atomic - Unmap a page obtained by dma_buf_kmap_atomic.
|
||||
* @dma_buf: [in] buffer to unmap page from.
|
||||
* @page_num: [in] page in PAGE_SIZE units to unmap.
|
||||
* @vaddr: [in] kernel space pointer obtained from dma_buf_kmap_atomic.
|
||||
*
|
||||
* This call must always succeed.
|
||||
*/
|
||||
void dma_buf_kunmap_atomic(struct dma_buf *dmabuf, unsigned long page_num,
|
||||
void *vaddr)
|
||||
{
|
||||
WARN_ON(!dmabuf);
|
||||
|
||||
if (dmabuf->ops->kunmap_atomic)
|
||||
dmabuf->ops->kunmap_atomic(dmabuf, page_num, vaddr);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(dma_buf_kunmap_atomic);
|
||||
|
||||
/**
|
||||
* dma_buf_kmap - Map a page of the buffer object into kernel address space. The
|
||||
* same restrictions as for kmap and friends apply.
|
||||
* @dma_buf: [in] buffer to map page from.
|
||||
* @page_num: [in] page in PAGE_SIZE units to map.
|
||||
*
|
||||
* This call must always succeed, any necessary preparations that might fail
|
||||
* need to be done in begin_cpu_access.
|
||||
*/
|
||||
void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num)
|
||||
{
|
||||
WARN_ON(!dmabuf);
|
||||
|
||||
return dmabuf->ops->kmap(dmabuf, page_num);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(dma_buf_kmap);
|
||||
|
||||
/**
|
||||
* dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap.
|
||||
* @dma_buf: [in] buffer to unmap page from.
|
||||
* @page_num: [in] page in PAGE_SIZE units to unmap.
|
||||
* @vaddr: [in] kernel space pointer obtained from dma_buf_kmap.
|
||||
*
|
||||
* This call must always succeed.
|
||||
*/
|
||||
void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
|
||||
void *vaddr)
|
||||
{
|
||||
WARN_ON(!dmabuf);
|
||||
|
||||
if (dmabuf->ops->kunmap)
|
||||
dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(dma_buf_kunmap);
|
||||
|
||||
@ -29,6 +29,7 @@
|
||||
#include <linux/scatterlist.h>
|
||||
#include <linux/list.h>
|
||||
#include <linux/dma-mapping.h>
|
||||
#include <linux/fs.h>
|
||||
|
||||
struct device;
|
||||
struct dma_buf;
|
||||
@ -49,6 +50,17 @@ struct dma_buf_attachment;
|
||||
* @unmap_dma_buf: decreases usecount of buffer, might deallocate scatter
|
||||
* pages.
|
||||
* @release: release this buffer; to be called after the last dma_buf_put.
|
||||
* @begin_cpu_access: [optional] called before cpu access to invalidate cpu
|
||||
* caches and allocate backing storage (if not yet done)
|
||||
* respectively pin the objet into memory.
|
||||
* @end_cpu_access: [optional] called after cpu access to flush cashes.
|
||||
* @kmap_atomic: maps a page from the buffer into kernel address
|
||||
* space, users may not block until the subsequent unmap call.
|
||||
* This callback must not sleep.
|
||||
* @kunmap_atomic: [optional] unmaps a atomically mapped page from the buffer.
|
||||
* This Callback must not sleep.
|
||||
* @kmap: maps a page from the buffer into kernel address space.
|
||||
* @kunmap: [optional] unmaps a page from the buffer.
|
||||
*/
|
||||
struct dma_buf_ops {
|
||||
int (*attach)(struct dma_buf *, struct device *,
|
||||
@ -63,7 +75,8 @@ struct dma_buf_ops {
|
||||
struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *,
|
||||
enum dma_data_direction);
|
||||
void (*unmap_dma_buf)(struct dma_buf_attachment *,
|
||||
struct sg_table *);
|
||||
struct sg_table *,
|
||||
enum dma_data_direction);
|
||||
/* TODO: Add try_map_dma_buf version, to return immed with -EBUSY
|
||||
* if the call would block.
|
||||
*/
|
||||
@ -71,6 +84,14 @@ struct dma_buf_ops {
|
||||
/* after final dma_buf_put() */
|
||||
void (*release)(struct dma_buf *);
|
||||
|
||||
int (*begin_cpu_access)(struct dma_buf *, size_t, size_t,
|
||||
enum dma_data_direction);
|
||||
void (*end_cpu_access)(struct dma_buf *, size_t, size_t,
|
||||
enum dma_data_direction);
|
||||
void *(*kmap_atomic)(struct dma_buf *, unsigned long);
|
||||
void (*kunmap_atomic)(struct dma_buf *, unsigned long, void *);
|
||||
void *(*kmap)(struct dma_buf *, unsigned long);
|
||||
void (*kunmap)(struct dma_buf *, unsigned long, void *);
|
||||
};
|
||||
|
||||
/**
|
||||
@ -86,7 +107,7 @@ struct dma_buf {
|
||||
struct file *file;
|
||||
struct list_head attachments;
|
||||
const struct dma_buf_ops *ops;
|
||||
/* mutex to serialize list manipulation and other ops */
|
||||
/* mutex to serialize list manipulation and attach/detach */
|
||||
struct mutex lock;
|
||||
void *priv;
|
||||
};
|
||||
@ -109,20 +130,43 @@ struct dma_buf_attachment {
|
||||
void *priv;
|
||||
};
|
||||
|
||||
/**
|
||||
* get_dma_buf - convenience wrapper for get_file.
|
||||
* @dmabuf: [in] pointer to dma_buf
|
||||
*
|
||||
* Increments the reference count on the dma-buf, needed in case of drivers
|
||||
* that either need to create additional references to the dmabuf on the
|
||||
* kernel side. For example, an exporter that needs to keep a dmabuf ptr
|
||||
* so that subsequent exports don't create a new dmabuf.
|
||||
*/
|
||||
static inline void get_dma_buf(struct dma_buf *dmabuf)
|
||||
{
|
||||
get_file(dmabuf->file);
|
||||
}
|
||||
|
||||
#ifdef CONFIG_DMA_SHARED_BUFFER
|
||||
struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
|
||||
struct device *dev);
|
||||
void dma_buf_detach(struct dma_buf *dmabuf,
|
||||
struct dma_buf_attachment *dmabuf_attach);
|
||||
struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
|
||||
size_t size, int flags);
|
||||
int dma_buf_fd(struct dma_buf *dmabuf);
|
||||
struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
|
||||
size_t size, int flags);
|
||||
int dma_buf_fd(struct dma_buf *dmabuf, int flags);
|
||||
struct dma_buf *dma_buf_get(int fd);
|
||||
void dma_buf_put(struct dma_buf *dmabuf);
|
||||
|
||||
struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
|
||||
enum dma_data_direction);
|
||||
void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *);
|
||||
void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
|
||||
enum dma_data_direction);
|
||||
int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
|
||||
enum dma_data_direction dir);
|
||||
void dma_buf_end_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
|
||||
enum dma_data_direction dir);
|
||||
void *dma_buf_kmap_atomic(struct dma_buf *, unsigned long);
|
||||
void dma_buf_kunmap_atomic(struct dma_buf *, unsigned long, void *);
|
||||
void *dma_buf_kmap(struct dma_buf *, unsigned long);
|
||||
void dma_buf_kunmap(struct dma_buf *, unsigned long, void *);
|
||||
#else
|
||||
|
||||
static inline struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
|
||||
@ -138,13 +182,13 @@ static inline void dma_buf_detach(struct dma_buf *dmabuf,
|
||||
}
|
||||
|
||||
static inline struct dma_buf *dma_buf_export(void *priv,
|
||||
struct dma_buf_ops *ops,
|
||||
size_t size, int flags)
|
||||
const struct dma_buf_ops *ops,
|
||||
size_t size, int flags)
|
||||
{
|
||||
return ERR_PTR(-ENODEV);
|
||||
}
|
||||
|
||||
static inline int dma_buf_fd(struct dma_buf *dmabuf)
|
||||
static inline int dma_buf_fd(struct dma_buf *dmabuf, int flags)
|
||||
{
|
||||
return -ENODEV;
|
||||
}
|
||||
@ -166,11 +210,44 @@ static inline struct sg_table *dma_buf_map_attachment(
|
||||
}
|
||||
|
||||
static inline void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
|
||||
struct sg_table *sg)
|
||||
struct sg_table *sg, enum dma_data_direction dir)
|
||||
{
|
||||
return;
|
||||
}
|
||||
|
||||
static inline int dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
|
||||
size_t start, size_t len,
|
||||
enum dma_data_direction dir)
|
||||
{
|
||||
return -ENODEV;
|
||||
}
|
||||
|
||||
static inline void dma_buf_end_cpu_access(struct dma_buf *dmabuf,
|
||||
size_t start, size_t len,
|
||||
enum dma_data_direction dir)
|
||||
{
|
||||
}
|
||||
|
||||
static inline void *dma_buf_kmap_atomic(struct dma_buf *dmabuf,
|
||||
unsigned long pnum)
|
||||
{
|
||||
return NULL;
|
||||
}
|
||||
|
||||
static inline void dma_buf_kunmap_atomic(struct dma_buf *dmabuf,
|
||||
unsigned long pnum, void *vaddr)
|
||||
{
|
||||
}
|
||||
|
||||
static inline void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long pnum)
|
||||
{
|
||||
return NULL;
|
||||
}
|
||||
|
||||
static inline void dma_buf_kunmap(struct dma_buf *dmabuf,
|
||||
unsigned long pnum, void *vaddr)
|
||||
{
|
||||
}
|
||||
#endif /* CONFIG_DMA_SHARED_BUFFER */
|
||||
|
||||
#endif /* __DMA_BUF_H__ */
|
||||
|
||||
Loading…
Reference in New Issue
Block a user