From: InKi Dae <daeinki@gmail.com>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: linaro-mm-sig@lists.linaro.org,
LKML <linux-kernel@vger.kernel.org>,
DRI Development <dri-devel@lists.freedesktop.org>,
Rob Clark <rob.clark@linaro.org>,
Rebecca Schultz Zavin <rebecca@android.com>,
linux-media@vger.kernel.org
Subject: Re: [PATCH] dma-buf: mmap support
Date: Wed, 25 Apr 2012 01:37:51 +0900 [thread overview]
Message-ID: <CAAQKjZMgcxWc44xknM+eZhon4QgvWd92Ci4snwBv2Ziyw1Recw@mail.gmail.com> (raw)
In-Reply-To: <1335258532-20739-1-git-send-email-daniel.vetter@ffwll.ch>
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
next prev parent reply other threads:[~2012-04-24 16:37 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-24 9:08 [PATCH] dma-buf: mmap support Daniel Vetter
2012-04-24 16:37 ` InKi Dae [this message]
2012-04-24 17:02 ` Daniel Vetter
2012-04-25 2:31 ` InKi Dae
2012-05-11 15:30 ` Rob Clark
2012-05-18 4:12 ` Sumit Semwal
-- strict thread matches above, loose matches on Subject: below --
2012-04-18 13:52 Daniel Vetter
2012-04-18 14:06 ` Arnd Bergmann
2012-04-18 14:20 ` Rob Clark
2012-04-18 14:24 ` Daniel Vetter
2012-04-18 19:10 ` Alan Cox
2012-04-23 23:00 ` Rebecca Schultz Zavin
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