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Date:   Fri, 29 Mar 2019 17:01:57 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Zeng Tao <prime.zeng@hisilicon.com>
Cc:     labbott@redhat.com, sumit.semwal@linaro.org,
        devel@driverdev.osuosl.org, Todd Kjos <tkjos@android.com>,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linaro-mm-sig@lists.linaro.org,
        Arve =?iso-8859-1?B?SGr4bm5lduVn?= <arve@android.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Martijn Coenen <maco@android.com>,
        Christian Brauner <christian@brauner.io>
Subject: Re: [PATCH] staging: android: ion: refactory ion_alloc for kernel
 driver use
Message-ID: <20190329160157.GA5906@kroah.com>
References: <1553884816-37850-1-git-send-email-prime.zeng@hisilicon.com>
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In-Reply-To: <1553884816-37850-1-git-send-email-prime.zeng@hisilicon.com>
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Sender: linux-kernel-owner@vger.kernel.org
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On Sat, Mar 30, 2019 at 02:40:16AM +0800, Zeng Tao wrote:
> There are two reasons for this patch:
> 1. There are some potential requirements for ion_alloc in kernel space,
> some media drivers need to allocate media buffers from ion instead of
> buddy or dma framework, this is more convient and clean very for media
> drivers. And In that case, ion is the only media buffer provider, it's
> more easier to maintain.
> 2. Fd is only needed by user processes, not the kernel space, so dma_buf
> should be returned instead of fd for kernel space, and dma_buf_fd should
> be called only for userspace api.
> 
> Signed-off-by: Zeng Tao <prime.zeng@hisilicon.com>
> ---
>  drivers/staging/android/ion/ion.c | 32 +++++++++++++++++---------------
>  1 file changed, 17 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
> index 92c2914..e93fb49 100644
> --- a/drivers/staging/android/ion/ion.c
> +++ b/drivers/staging/android/ion/ion.c
> @@ -387,13 +387,13 @@ static const struct dma_buf_ops dma_buf_ops = {
>  	.unmap = ion_dma_buf_kunmap,
>  };
>  
> -static int ion_alloc(size_t len, unsigned int heap_id_mask, unsigned int flags)
> +struct dma_buf *ion_alloc(size_t len, unsigned int heap_id_mask,
> +			  unsigned int flags)
>  {
>  	struct ion_device *dev = internal_dev;
>  	struct ion_buffer *buffer = NULL;
>  	struct ion_heap *heap;
>  	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> -	int fd;
>  	struct dma_buf *dmabuf;
>  
>  	pr_debug("%s: len %zu heap_id_mask %u flags %x\n", __func__,
> @@ -407,7 +407,7 @@ static int ion_alloc(size_t len, unsigned int heap_id_mask, unsigned int flags)
>  	len = PAGE_ALIGN(len);
>  
>  	if (!len)
> -		return -EINVAL;
> +		return ERR_PTR(-EINVAL);
>  
>  	down_read(&dev->lock);
>  	plist_for_each_entry(heap, &dev->heaps, node) {
> @@ -421,10 +421,10 @@ static int ion_alloc(size_t len, unsigned int heap_id_mask, unsigned int flags)
>  	up_read(&dev->lock);
>  
>  	if (!buffer)
> -		return -ENODEV;
> +		return ERR_PTR(-ENODEV);
>  
>  	if (IS_ERR(buffer))
> -		return PTR_ERR(buffer);
> +		return ERR_PTR(PTR_ERR(buffer));
>  
>  	exp_info.ops = &dma_buf_ops;
>  	exp_info.size = buffer->size;
> @@ -432,17 +432,12 @@ static int ion_alloc(size_t len, unsigned int heap_id_mask, unsigned int flags)
>  	exp_info.priv = buffer;
>  
>  	dmabuf = dma_buf_export(&exp_info);
> -	if (IS_ERR(dmabuf)) {
> +	if (IS_ERR(dmabuf))
>  		_ion_buffer_destroy(buffer);
> -		return PTR_ERR(dmabuf);
> -	}
>  
> -	fd = dma_buf_fd(dmabuf, O_CLOEXEC);
> -	if (fd < 0)
> -		dma_buf_put(dmabuf);
> -
> -	return fd;
> +	return dmabuf;
>  }
> +EXPORT_SYMBOL(ion_alloc);

If you are going to do this (and personally I'm with Laura in that I
don't think you need it) this should be EXPORT_SYMBOL_GPL() please.

thanks,

greg k-h