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    SubjectRe: [PATCH] dma-buf: mmap support
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    Hi,

    >
    > +static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
    > +{
    > +       struct dma_buf *dmabuf;
    > +
    > +       if (!is_dma_buf_file(file))
    > +               return -EINVAL;
    > +
    > +       dmabuf = file->private_data;
    > +
    > +       /* check for overflowing the buffer's size */
    > +       if (vma->vm_pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
    > +           dmabuf->size >> PAGE_SHIFT)

    is this condition right? your intention is for checking buffer's size
    is valid or not. by the way why is vma->vm_pgoff added to vm region
    size?

    > +               return -EINVAL;
    > +
    > +       return dmabuf->ops->mmap(dmabuf, vma);
    > +}
    > +
    >  static const struct file_operations dma_buf_fops = {
    >        .release        = dma_buf_release,
    > +       .mmap           = dma_buf_mmap_internal,
    >  };
    >
    >  /*
    > @@ -82,7 +100,8 @@ struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
    >                          || !ops->unmap_dma_buf
    >                          || !ops->release
    >                          || !ops->kmap_atomic
    > -                         || !ops->kmap)) {
    > +                         || !ops->kmap
    > +                         || !ops->mmap)) {
    >                return ERR_PTR(-EINVAL);
    >        }
    >
    > @@ -406,3 +425,46 @@ void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
    >                dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
    >  }
    >  EXPORT_SYMBOL_GPL(dma_buf_kunmap);
    > +
    > +
    > +/**
    > + * dma_buf_mmap - Setup up a userspace mmap with the given vma
    > + * @dma_buf:   [in]    buffer that should back the vma
    > + * @vma:       [in]    vma for the mmap
    > + * @pgoff:     [in]    offset in pages where this mmap should start within the
    > + *                     dma-buf buffer.
    > + *
    > + * This function adjusts the passed in vma so that it points at the file of the
    > + * dma_buf operation. It alsog adjusts the starting pgoff and does bounds
    > + * checking on the size of the vma. Then it calls the exporters mmap function to
    > + * set up the mapping.
    > + *
    > + * Can return negative error values, returns 0 on success.
    > + */
    > +int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
    > +                unsigned long pgoff)
    > +{
    > +       if (WARN_ON(!dmabuf || !vma))
    > +               return -EINVAL;
    > +
    > +       /* check for offset overflow */
    > +       if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) < pgoff)

    ditto. isn't it checked whether page offset to be mmaped is placed
    within vm region or not with the condition, if ((vma->vm_end -
    vma->vm_start) >> PAGE_SHIFT) < pgoff)?

    > +               return -EOVERFLOW;
    > +
    > +       /* check for overflowing the buffer's size */
    > +       if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
    > +           dmabuf->size >> PAGE_SHIFT)
    > +               return -EINVAL;
    > +
    > +       /* readjust the vma */
    > +       if (vma->vm_file)
    > +               fput(vma->vm_file);
    > +
    > +       vma->vm_file = dmabuf->file;
    > +       get_file(vma->vm_file);
    > +
    > +       vma->vm_pgoff = pgoff;
    > +
    > +       return dmabuf->ops->mmap(dmabuf, vma);
    > +}
    > +EXPORT_SYMBOL_GPL(dma_buf_mmap);
    > diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
    > index 3efbfc2..1f78d15 100644
    > --- a/include/linux/dma-buf.h
    > +++ b/include/linux/dma-buf.h
    > @@ -61,6 +61,10 @@ struct dma_buf_attachment;
    >  *                This Callback must not sleep.
    >  * @kmap: maps a page from the buffer into kernel address space.
    >  * @kunmap: [optional] unmaps a page from the buffer.
    > + * @mmap: used to expose the backing storage to userspace. Note that the
    > + *       mapping needs to be coherent - if the exporter doesn't directly
    > + *       support this, it needs to fake coherency by shooting down any ptes
    > + *       when transitioning away from the cpu domain.
    >  */
    >  struct dma_buf_ops {
    >        int (*attach)(struct dma_buf *, struct device *,
    > @@ -92,6 +96,8 @@ struct dma_buf_ops {
    >        void (*kunmap_atomic)(struct dma_buf *, unsigned long, void *);
    >        void *(*kmap)(struct dma_buf *, unsigned long);
    >        void (*kunmap)(struct dma_buf *, unsigned long, void *);
    > +
    > +       int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);
    >  };
    >
    >  /**
    > @@ -167,6 +173,9 @@ 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 *);
    > +
    > +int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
    > +                unsigned long);
    >  #else
    >
    >  static inline struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
    > @@ -248,6 +257,13 @@ static inline void dma_buf_kunmap(struct dma_buf *dmabuf,
    >                                  unsigned long pnum, void *vaddr)
    >  {
    >  }
    > +
    > +static inline int dma_buf_mmap(struct dma_buf *dmabuf,
    > +                              struct vm_area_struct *vma,
    > +                              unsigned long pgoff)
    > +{
    > +       return -ENODEV;
    > +}
    >  #endif /* CONFIG_DMA_SHARED_BUFFER */
    >
    >  #endif /* __DMA_BUF_H__ */
    > --
    > 1.7.10
    >
    > _______________________________________________
    > dri-devel mailing list
    > dri-devel@lists.freedesktop.org
    > http://lists.freedesktop.org/mailman/listinfo/dri-devel
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