diff mbox series

staging: android: ion: refactory ion_alloc for kernel driver use

Message ID 1553884816-37850-1-git-send-email-prime.zeng@hisilicon.com
State New
Headers show
Series staging: android: ion: refactory ion_alloc for kernel driver use | expand

Commit Message

Zeng Tao March 29, 2019, 6:40 p.m. UTC 
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(-)

-- 
2.7.4

Comments

Laura Abbott March 29, 2019, 1:27 p.m. UTC | #1 
On 3/29/19 11:40 AM, 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.

> 


I really want to just NAK this because it doesn't seem like something
that's necessary. The purpose of Ion is to provide buffers to userspace
because there's no other way for userspace to get access to the memory.
The kernel already has other APIs to access the memory. This also
complicates the re-work that's been happening where the requirement
is only userspace.

Can you be more detailed about which media drivers you are referring
to and why they can't just use other APIs?


> 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);

>   

>   static int ion_query_heaps(struct ion_heap_query *query)

>   {

> @@ -539,12 +534,19 @@ static long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)

>   	case ION_IOC_ALLOC:

>   	{

>   		int fd;

> +		struct dma_buf *dmabuf;

>   

> -		fd = ion_alloc(data.allocation.len,

> +		dmabuf = ion_alloc(data.allocation.len,

>   			       data.allocation.heap_id_mask,

>   			       data.allocation.flags);

> -		if (fd < 0)

> +		if (IS_ERR(dmabuf))

> +			return PTR_ERR(dmabuf);

> +

> +		fd = dma_buf_fd(dmabuf, O_CLOEXEC);

> +		if (fd < 0) {

> +			dma_buf_put(dmabuf);

>   			return fd;

> +		}

>   

>   		data.allocation.fd = fd;

>   

>
Zeng Tao March 30, 2019, 2:26 a.m. UTC | #2 
Hi laura: 

>-----Original Message-----

>From: Laura Abbott [mailto:labbott@redhat.com]

>Sent: Friday, March 29, 2019 9:27 PM

>To: Zengtao (B) <prime.zeng@hisilicon.com>; sumit.semwal@linaro.org

>Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>; Arve Hjønnevåg

><arve@android.com>; Todd Kjos <tkjos@android.com>; Martijn Coenen

><maco@android.com>; Joel Fernandes <joel@joelfernandes.org>;

>Christian Brauner <christian@brauner.io>; devel@driverdev.osuosl.org;

>dri-devel@lists.freedesktop.org; linaro-mm-sig@lists.linaro.org;

>linux-kernel@vger.kernel.org

>Subject: Re: [PATCH] staging: android: ion: refactory ion_alloc for kernel

>driver use

>

>On 3/29/19 11:40 AM, 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.

>>

>

>I really want to just NAK this because it doesn't seem like something

>that's necessary. The purpose of Ion is to provide buffers to userspace

>because there's no other way for userspace to get access to the memory.

>The kernel already has other APIs to access the memory. This also

>complicates the re-work that's been happening where the requirement is

>only userspace.

>

>Can you be more detailed about which media drivers you are referring to

>and why they can't just use other APIs?

>


I think I 've got your point, the ION is designed for usespace, but for kernel
 space, we are really lacking of someone which plays the same role,(allocate 
media memory, share the memory using dma_buf, provide debug and statistics
for media memory).

In fact, for kernel space, we have the dma framework, dma-buf, etc..
And we can work on top of such apis, but some duplicate jobs(everyone has
 to maintain its own buffer sharing, debug and statistics).
So we need to have some to do the common things(ION's the best choice now)

When the ION was introduced, a lot of media memory frameworks existed, the
dma framework was not so good, so ION heaps, integrated buffer sharing, statistics
and usespace api were the required features, but now dma framework is more powerful,
we don't even need ION heaps now, but the userspace api, buffer sharing, statistics are
still needed, and the buffer sharing, statistics can be re-worked and export to kernel space,
not only used by userspace, , and that is my point.

>

>> 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);

>>

>>   static int ion_query_heaps(struct ion_heap_query *query)

>>   {

>> @@ -539,12 +534,19 @@ static long ion_ioctl(struct file *filp, unsigned

>int cmd, unsigned long arg)

>>   	case ION_IOC_ALLOC:

>>   	{

>>   		int fd;

>> +		struct dma_buf *dmabuf;

>>

>> -		fd = ion_alloc(data.allocation.len,

>> +		dmabuf = ion_alloc(data.allocation.len,

>>   			       data.allocation.heap_id_mask,

>>   			       data.allocation.flags);

>> -		if (fd < 0)

>> +		if (IS_ERR(dmabuf))

>> +			return PTR_ERR(dmabuf);

>> +

>> +		fd = dma_buf_fd(dmabuf, O_CLOEXEC);

>> +		if (fd < 0) {

>> +			dma_buf_put(dmabuf);

>>   			return fd;

>> +		}

>>

>>   		data.allocation.fd = fd;

>>

>>
Zeng Tao March 30, 2019, 2:27 a.m. UTC | #3 
>-----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
Zeng Tao March 30, 2019, 2:32 a.m. UTC | #4 
>-----Original Message-----

>From: Greg Kroah-Hartman [mailto:gregkh@linuxfoundation.org]

>Sent: Saturday, March 30, 2019 12:04 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.

>

>As this really is just DMA, what is wrong with the existing dma framework

>that makes it hard to use?  You have seen all of the changes recently to it,

>right?


The current dma framework is powerful enough(to me, and more complex ^_^)
, CMA, IOMMU are all integrated, it's good. But buffer sharing, statistics, debug,
 are not so friendly for media drivers(each driver has to do all, but duplicate jobs).

>

>thanks,

>

>greg k-h
Zeng Tao March 30, 2019, 2:33 a.m. UTC | #5 
>-----Original Message-----

>From: Dan Carpenter [mailto:dan.carpenter@oracle.com]

>Sent: Friday, March 29, 2019 7:03 PM

>To: Zengtao (B) <prime.zeng@hisilicon.com>

>Cc: labbott@redhat.com; sumit.semwal@linaro.org;

>devel@driverdev.osuosl.org; Todd Kjos <tkjos@android.com>; Greg

>Kroah-Hartman <gregkh@linuxfoundation.org>;

>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

>

>If we're going to export ion_alloc() for other drivers to use then let's make

>an ion_free() helper function as well.

>


Good catch, thanks. 

Regards
Zengtao 

>void ion_free(struct dma_buf *dmabuf)

>{

>	dma_buf_put(dmabuf);

>}

>

>regards,

>dan carpenter
kernel test robot March 30, 2019, 1:09 p.m. UTC | #6 
Hi Zeng,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on staging/staging-testing]
[also build test WARNING on v5.1-rc2 next-20190329]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Zeng-Tao/staging-android-ion-refactory-ion_alloc-for-kernel-driver-use/20190330-071409


coccinelle warnings: (new ones prefixed by >>)

>> drivers/staging/android/ion/ion.c:427:9-16: WARNING: ERR_CAST can be used with buffer


Please review and possibly fold the followup patch.

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
diff mbox series

Patch

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);
 
 static int ion_query_heaps(struct ion_heap_query *query)
 {
@@ -539,12 +534,19 @@  static long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	case ION_IOC_ALLOC:
 	{
 		int fd;
+		struct dma_buf *dmabuf;
 
-		fd = ion_alloc(data.allocation.len,
+		dmabuf = ion_alloc(data.allocation.len,
 			       data.allocation.heap_id_mask,
 			       data.allocation.flags);
-		if (fd < 0)
+		if (IS_ERR(dmabuf))
+			return PTR_ERR(dmabuf);
+
+		fd = dma_buf_fd(dmabuf, O_CLOEXEC);
+		if (fd < 0) {
+			dma_buf_put(dmabuf);
 			return fd;
+		}
 
 		data.allocation.fd = fd;