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![Rob Clark](/assets/img/avatar_default.png)
We never really clarified if unmap could be done in atomic context. But since mapping might require sleeping, this implies mutex in use to synchronize mapping/unmapping, so unmap could sleep as well. Add a might_sleep() to clarify this. Signed-off-by: Rob Clark <rob@ti.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
507 lines
14 KiB
C
507 lines
14 KiB
C
/*
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* Framework for buffer objects that can be shared across devices/subsystems.
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*
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* Copyright(C) 2011 Linaro Limited. All rights reserved.
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* Author: Sumit Semwal <sumit.semwal@ti.com>
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*
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* Many thanks to linaro-mm-sig list, and specially
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* Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and
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* Daniel Vetter <daniel@ffwll.ch> for their support in creation and
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* refining of this idea.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/fs.h>
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#include <linux/slab.h>
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#include <linux/dma-buf.h>
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#include <linux/anon_inodes.h>
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#include <linux/export.h>
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static inline int is_dma_buf_file(struct file *);
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static int dma_buf_release(struct inode *inode, struct file *file)
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{
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struct dma_buf *dmabuf;
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if (!is_dma_buf_file(file))
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return -EINVAL;
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dmabuf = file->private_data;
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dmabuf->ops->release(dmabuf);
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kfree(dmabuf);
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return 0;
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}
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static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
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{
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struct dma_buf *dmabuf;
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if (!is_dma_buf_file(file))
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return -EINVAL;
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dmabuf = file->private_data;
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/* check for overflowing the buffer's size */
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if (vma->vm_pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
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dmabuf->size >> PAGE_SHIFT)
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return -EINVAL;
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return dmabuf->ops->mmap(dmabuf, vma);
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}
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static const struct file_operations dma_buf_fops = {
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.release = dma_buf_release,
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.mmap = dma_buf_mmap_internal,
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};
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/*
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* is_dma_buf_file - Check if struct file* is associated with dma_buf
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*/
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static inline int is_dma_buf_file(struct file *file)
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{
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return file->f_op == &dma_buf_fops;
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}
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/**
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* dma_buf_export - Creates a new dma_buf, and associates an anon file
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* with this buffer, so it can be exported.
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* Also connect the allocator specific data and ops to the buffer.
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*
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* @priv: [in] Attach private data of allocator to this buffer
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* @ops: [in] Attach allocator-defined dma buf ops to the new buffer.
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* @size: [in] Size of the buffer
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* @flags: [in] mode flags for the file.
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*
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* Returns, on success, a newly created dma_buf object, which wraps the
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* supplied private data and operations for dma_buf_ops. On either missing
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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, 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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struct file *file;
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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->kmap_atomic
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|| !ops->kmap
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|| !ops->mmap)) {
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return ERR_PTR(-EINVAL);
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}
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dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL);
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if (dmabuf == NULL)
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return ERR_PTR(-ENOMEM);
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dmabuf->priv = priv;
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dmabuf->ops = ops;
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dmabuf->size = size;
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file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
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dmabuf->file = file;
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mutex_init(&dmabuf->lock);
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INIT_LIST_HEAD(&dmabuf->attachments);
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return dmabuf;
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}
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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, 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_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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fd_install(fd, dmabuf->file);
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return fd;
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}
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EXPORT_SYMBOL_GPL(dma_buf_fd);
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/**
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* dma_buf_get - returns the dma_buf structure related to an fd
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* @fd: [in] fd associated with the dma_buf to be returned
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*
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* On success, returns the dma_buf structure associated with an fd; uses
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* file's refcounting done by fget to increase refcount. returns ERR_PTR
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* otherwise.
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*/
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struct dma_buf *dma_buf_get(int fd)
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{
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struct file *file;
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file = fget(fd);
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if (!file)
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return ERR_PTR(-EBADF);
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if (!is_dma_buf_file(file)) {
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fput(file);
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return ERR_PTR(-EINVAL);
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}
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return file->private_data;
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}
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EXPORT_SYMBOL_GPL(dma_buf_get);
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/**
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* dma_buf_put - decreases refcount of the buffer
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* @dmabuf: [in] buffer to reduce refcount of
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*
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* Uses file's refcounting done implicitly by fput()
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*/
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void dma_buf_put(struct dma_buf *dmabuf)
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{
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if (WARN_ON(!dmabuf || !dmabuf->file))
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return;
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fput(dmabuf->file);
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}
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EXPORT_SYMBOL_GPL(dma_buf_put);
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/**
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* dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
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* calls attach() of dma_buf_ops to allow device-specific attach functionality
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* @dmabuf: [in] buffer to attach device to.
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* @dev: [in] device to be attached.
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*
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* Returns struct dma_buf_attachment * for this attachment; may return negative
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* error codes.
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*
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*/
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struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
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struct device *dev)
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{
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struct dma_buf_attachment *attach;
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int ret;
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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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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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goto err_attach;
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}
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list_add(&attach->node, &dmabuf->attachments);
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mutex_unlock(&dmabuf->lock);
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return attach;
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err_attach:
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kfree(attach);
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mutex_unlock(&dmabuf->lock);
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return ERR_PTR(ret);
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}
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EXPORT_SYMBOL_GPL(dma_buf_attach);
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/**
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* dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
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* optionally calls detach() of dma_buf_ops for device-specific detach
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* @dmabuf: [in] buffer to detach from.
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* @attach: [in] attachment to be detached; is free'd after this call.
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*
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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))
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return;
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mutex_lock(&dmabuf->lock);
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list_del(&attach->node);
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if (dmabuf->ops->detach)
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dmabuf->ops->detach(dmabuf, attach);
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mutex_unlock(&dmabuf->lock);
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kfree(attach);
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}
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EXPORT_SYMBOL_GPL(dma_buf_detach);
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/**
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* dma_buf_map_attachment - Returns the scatterlist table of the attachment;
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* mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
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* dma_buf_ops.
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* @attach: [in] attachment whose scatterlist is to be returned
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* @direction: [in] direction of DMA transfer
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*
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* Returns sg_table containing the scatterlist to be returned; may return NULL
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* or ERR_PTR.
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*
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*/
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struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
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enum dma_data_direction direction)
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{
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struct sg_table *sg_table = ERR_PTR(-EINVAL);
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might_sleep();
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if (WARN_ON(!attach || !attach->dmabuf))
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return ERR_PTR(-EINVAL);
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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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EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
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/**
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* dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
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* deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
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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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enum dma_data_direction direction)
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{
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might_sleep();
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if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
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return;
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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
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* preparations. Coherency is only guaranteed in the specified range for the
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* specified access direction.
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* @dmabuf: [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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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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}
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EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);
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/**
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* dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
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* cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
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* actions. Coherency is only guaranteed in the specified range for the
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* specified access direction.
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* @dmabuf: [in] buffer to complete 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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* This call must always succeed.
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*/
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void dma_buf_end_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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WARN_ON(!dmabuf);
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if (dmabuf->ops->end_cpu_access)
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dmabuf->ops->end_cpu_access(dmabuf, start, len, direction);
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}
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EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
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/**
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* dma_buf_kmap_atomic - Map a page of the buffer object into kernel address
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* space. The same restrictions as for kmap_atomic and friends apply.
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* @dmabuf: [in] buffer to map page from.
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* @page_num: [in] page in PAGE_SIZE units to map.
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*
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* This call must always succeed, any necessary preparations that might fail
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* need to be done in begin_cpu_access.
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*/
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void *dma_buf_kmap_atomic(struct dma_buf *dmabuf, unsigned long page_num)
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{
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WARN_ON(!dmabuf);
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return dmabuf->ops->kmap_atomic(dmabuf, page_num);
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}
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EXPORT_SYMBOL_GPL(dma_buf_kmap_atomic);
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/**
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* dma_buf_kunmap_atomic - Unmap a page obtained by dma_buf_kmap_atomic.
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* @dmabuf: [in] buffer to unmap page from.
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* @page_num: [in] page in PAGE_SIZE units to unmap.
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* @vaddr: [in] kernel space pointer obtained from dma_buf_kmap_atomic.
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*
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* This call must always succeed.
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*/
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void dma_buf_kunmap_atomic(struct dma_buf *dmabuf, unsigned long page_num,
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void *vaddr)
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{
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WARN_ON(!dmabuf);
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if (dmabuf->ops->kunmap_atomic)
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dmabuf->ops->kunmap_atomic(dmabuf, page_num, vaddr);
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}
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EXPORT_SYMBOL_GPL(dma_buf_kunmap_atomic);
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/**
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* dma_buf_kmap - Map a page of the buffer object into kernel address space. The
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* same restrictions as for kmap and friends apply.
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* @dmabuf: [in] buffer to map page from.
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* @page_num: [in] page in PAGE_SIZE units to map.
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*
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* This call must always succeed, any necessary preparations that might fail
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* need to be done in begin_cpu_access.
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*/
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void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num)
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{
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WARN_ON(!dmabuf);
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return dmabuf->ops->kmap(dmabuf, page_num);
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}
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EXPORT_SYMBOL_GPL(dma_buf_kmap);
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/**
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* dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap.
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* @dmabuf: [in] buffer to unmap page from.
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* @page_num: [in] page in PAGE_SIZE units to unmap.
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* @vaddr: [in] kernel space pointer obtained from dma_buf_kmap.
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*
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* This call must always succeed.
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*/
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void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
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void *vaddr)
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{
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WARN_ON(!dmabuf);
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if (dmabuf->ops->kunmap)
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dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
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}
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EXPORT_SYMBOL_GPL(dma_buf_kunmap);
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/**
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* dma_buf_mmap - Setup up a userspace mmap with the given vma
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* @dmabuf: [in] buffer that should back the vma
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* @vma: [in] vma for the mmap
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* @pgoff: [in] offset in pages where this mmap should start within the
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* dma-buf buffer.
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*
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* This function adjusts the passed in vma so that it points at the file of the
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* dma_buf operation. It alsog adjusts the starting pgoff and does bounds
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* checking on the size of the vma. Then it calls the exporters mmap function to
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* set up the mapping.
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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_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
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unsigned long pgoff)
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{
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if (WARN_ON(!dmabuf || !vma))
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return -EINVAL;
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/* check for offset overflow */
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if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) < pgoff)
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return -EOVERFLOW;
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/* check for overflowing the buffer's size */
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if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
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dmabuf->size >> PAGE_SHIFT)
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return -EINVAL;
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/* readjust the vma */
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if (vma->vm_file)
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fput(vma->vm_file);
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vma->vm_file = get_file(dmabuf->file);
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vma->vm_pgoff = pgoff;
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return dmabuf->ops->mmap(dmabuf, vma);
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}
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EXPORT_SYMBOL_GPL(dma_buf_mmap);
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/**
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* dma_buf_vmap - Create virtual mapping for the buffer object into kernel
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* address space. Same restrictions as for vmap and friends apply.
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* @dmabuf: [in] buffer to vmap
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*
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* This call may fail due to lack of virtual mapping address space.
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* These calls are optional in drivers. The intended use for them
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* is for mapping objects linear in kernel space for high use objects.
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* Please attempt to use kmap/kunmap before thinking about these interfaces.
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*/
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void *dma_buf_vmap(struct dma_buf *dmabuf)
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{
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if (WARN_ON(!dmabuf))
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return NULL;
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if (dmabuf->ops->vmap)
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return dmabuf->ops->vmap(dmabuf);
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return NULL;
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}
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EXPORT_SYMBOL_GPL(dma_buf_vmap);
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/**
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* dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
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* @dmabuf: [in] buffer to vunmap
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* @vaddr: [in] vmap to vunmap
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*/
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void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
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{
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if (WARN_ON(!dmabuf))
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return;
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if (dmabuf->ops->vunmap)
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dmabuf->ops->vunmap(dmabuf, vaddr);
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}
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EXPORT_SYMBOL_GPL(dma_buf_vunmap);
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