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    Subject[PATCH v2] dma-buf: remove restriction of IOCTL:DMA_BUF_SET_NAME
    Date
    From: Guangming Cao <Guangming.Cao@mediatek.com>

    If dma-buf don't want userspace users to touch the dmabuf buffer,
    it seems we should add this restriction into dma_buf_ops.mmap,
    not in this IOCTL:DMA_BUF_SET_NAME.

    With this restriction, we can only know the kernel users of the dmabuf
    by attachments.
    However, for many userspace users, such as userpsace users of dma_heap,
    they also need to mark the usage of dma-buf, and they don't care about
    who attached to this dmabuf, and seems it's no meaning to be waiting for
    IOCTL:DMA_BUF_SET_NAME rather than mmap.

    Signed-off-by: Guangming Cao <Guangming.Cao@mediatek.com>
    ---
    drivers/dma-buf/dma-buf.c | 14 ++------------
    1 file changed, 2 insertions(+), 12 deletions(-)

    diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
    index 511fe0d217a0..db2f4efdec32 100644
    --- a/drivers/dma-buf/dma-buf.c
    +++ b/drivers/dma-buf/dma-buf.c
    @@ -325,10 +325,8 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)

    /**
    * dma_buf_set_name - Set a name to a specific dma_buf to track the usage.
    - * The name of the dma-buf buffer can only be set when the dma-buf is not
    - * attached to any devices. It could theoritically support changing the
    - * name of the dma-buf if the same piece of memory is used for multiple
    - * purpose between different devices.
    + * It could theoretically support changing the name of the dma-buf if the same
    + * piece of memory is used for multiple purpose between different devices.
    *
    * @dmabuf: [in] dmabuf buffer that will be renamed.
    * @buf: [in] A piece of userspace memory that contains the name of
    @@ -346,19 +344,11 @@ static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
    if (IS_ERR(name))
    return PTR_ERR(name);

    - dma_resv_lock(dmabuf->resv, NULL);
    - if (!list_empty(&dmabuf->attachments)) {
    - ret = -EBUSY;
    - kfree(name);
    - goto out_unlock;
    - }
    spin_lock(&dmabuf->name_lock);
    kfree(dmabuf->name);
    dmabuf->name = name;
    spin_unlock(&dmabuf->name_lock);

    -out_unlock:
    - dma_resv_unlock(dmabuf->resv);
    return ret;
    }

    --
    2.17.1
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