RE: [PATCH] staging: android: ion: refactory ion_alloc for kernel driver use

Zengtao (B)
2019-03-30T02:27:37Z

>-----Original Message-----
>From: Greg Kroah-Hartman [mailto:gregkh@linuxfoundation.org]
>Sent: Saturday, March 30, 2019 12:02 AM
>To: Zengtao (B) <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 Hjønnevåg <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
>
>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.
>
Agree, thanks

Regards
Zengtao

>thanks,
>
>greg k-h