diff mbox series

[v4] udmabuf: add vmap and vunmap methods to udmabuf_ops

Message ID 20221117045842.27161-1-lukasz.wiecaszek@gmail.com
State New
Headers
Series [v4] udmabuf: add vmap and vunmap methods to udmabuf_ops |

Commit Message

Lukasz Wiecaszek Nov. 17, 2022, 4:58 a.m. UTC 
  The reason behind that patch is associated with videobuf2 subsystem
(or more genrally with v4l2 framework) and user created
dma buffers (udmabuf). In some circumstances
when dealing with V4L2_MEMORY_DMABUF buffers videobuf2 subsystem
wants to use dma_buf_vmap() method on the attached dma buffer.
As udmabuf does not have .vmap operation implemented,
such dma_buf_vmap() natually fails.

videobuf2_common: __vb2_queue_alloc: allocated 3 buffers, 1 plane(s) each
videobuf2_common: __prepare_dmabuf: buffer for plane 0 changed
videobuf2_common: __prepare_dmabuf: failed to map dmabuf for plane 0
videobuf2_common: __buf_prepare: buffer preparation failed: -14

The patch itself seems to be strighforward.
It adds implementation of .vmap and .vunmap methods
to 'struct dma_buf_ops udmabuf_ops'.
.vmap method itself uses vm_map_ram() to map pages linearly
into the kernel virtual address space.
.vunmap removes mapping created earlier by .vmap.
All locking and 'vmapping counting' is done in dma_buf.c
so it seems to be redundant/unnecessary in .vmap/.vunmap.

Signed-off-by: Lukasz Wiecaszek <lukasz.wiecaszek@gmail.com>
---
v1: https://lore.kernel.org/linux-media/202211120352.G7WPASoP-lkp@intel.com/T/#t
v2: https://lore.kernel.org/linux-media/20221114052944.GA7264@thinkpad-p72/T/#t
v3: https://lore.kernel.org/linux-media/4f92e95f-a0dc-4eac-4c08-0df85de78ae7@collabora.com/T/#t

v3 -> v4: Removed line/info 'reported by kernel test robot'
v2 -> v3: Added .vunmap to 'struct dma_buf_ops udmabuf_ops'
v1 -> v2: Patch prepared and tested against 6.1.0-rc2+

 drivers/dma-buf/udmabuf.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

Comments

Dmitry Osipenko Nov. 17, 2022, 9:04 a.m. UTC | #1 
Hi,

On 11/17/22 07:58, Lukasz Wiecaszek wrote:
> The reason behind that patch is associated with videobuf2 subsystem
> (or more genrally with v4l2 framework) and user created
> dma buffers (udmabuf). In some circumstances
> when dealing with V4L2_MEMORY_DMABUF buffers videobuf2 subsystem
> wants to use dma_buf_vmap() method on the attached dma buffer.
> As udmabuf does not have .vmap operation implemented,
> such dma_buf_vmap() natually fails.
> 
> videobuf2_common: __vb2_queue_alloc: allocated 3 buffers, 1 plane(s) each
> videobuf2_common: __prepare_dmabuf: buffer for plane 0 changed
> videobuf2_common: __prepare_dmabuf: failed to map dmabuf for plane 0
> videobuf2_common: __buf_prepare: buffer preparation failed: -14
> 
> The patch itself seems to be strighforward.
> It adds implementation of .vmap and .vunmap methods
> to 'struct dma_buf_ops udmabuf_ops'.
> .vmap method itself uses vm_map_ram() to map pages linearly
> into the kernel virtual address space.
> .vunmap removes mapping created earlier by .vmap.
> All locking and 'vmapping counting' is done in dma_buf.c
> so it seems to be redundant/unnecessary in .vmap/.vunmap.
> 
> Signed-off-by: Lukasz Wiecaszek <lukasz.wiecaszek@gmail.com>

If new patch version doesn't contain significant changes and you got
acks/reviews for the previous version, then you should add the given
acked-by and reviewed-by tags to the commit message by yourself.
Lukasz Wiecaszek Nov. 17, 2022, 5:08 p.m. UTC | #2 
On Thu, Nov 17, 2022 at 12:04:35PM +0300, Dmitry Osipenko wrote:
> Hi,
> 
> On 11/17/22 07:58, Lukasz Wiecaszek wrote:
> > The reason behind that patch is associated with videobuf2 subsystem
> > (or more genrally with v4l2 framework) and user created
> > dma buffers (udmabuf). In some circumstances
> > when dealing with V4L2_MEMORY_DMABUF buffers videobuf2 subsystem
> > wants to use dma_buf_vmap() method on the attached dma buffer.
> > As udmabuf does not have .vmap operation implemented,
> > such dma_buf_vmap() natually fails.
> > 
> > videobuf2_common: __vb2_queue_alloc: allocated 3 buffers, 1 plane(s) each
> > videobuf2_common: __prepare_dmabuf: buffer for plane 0 changed
> > videobuf2_common: __prepare_dmabuf: failed to map dmabuf for plane 0
> > videobuf2_common: __buf_prepare: buffer preparation failed: -14
> > 
> > The patch itself seems to be strighforward.
> > It adds implementation of .vmap and .vunmap methods
> > to 'struct dma_buf_ops udmabuf_ops'.
> > .vmap method itself uses vm_map_ram() to map pages linearly
> > into the kernel virtual address space.
> > .vunmap removes mapping created earlier by .vmap.
> > All locking and 'vmapping counting' is done in dma_buf.c
> > so it seems to be redundant/unnecessary in .vmap/.vunmap.
> > 
> > Signed-off-by: Lukasz Wiecaszek <lukasz.wiecaszek@gmail.com>
> 
> If new patch version doesn't contain significant changes and you got
> acks/reviews for the previous version, then you should add the given
> acked-by and reviewed-by tags to the commit message by yourself.
> 
> -- 
> Best regards,
> Dmitry
>

I would like to thank you all for your patience and on the same time say
sorry that I still cannot follow the process (although I have read
'submitting patches' chapter).
Dmitry Osipenko Nov. 17, 2022, 5:32 p.m. UTC | #3 
On 11/17/22 20:08, Lukasz Wiecaszek wrote:
> On Thu, Nov 17, 2022 at 12:04:35PM +0300, Dmitry Osipenko wrote:
>> Hi,
>>
>> On 11/17/22 07:58, Lukasz Wiecaszek wrote:
>>> The reason behind that patch is associated with videobuf2 subsystem
>>> (or more genrally with v4l2 framework) and user created
>>> dma buffers (udmabuf). In some circumstances
>>> when dealing with V4L2_MEMORY_DMABUF buffers videobuf2 subsystem
>>> wants to use dma_buf_vmap() method on the attached dma buffer.
>>> As udmabuf does not have .vmap operation implemented,
>>> such dma_buf_vmap() natually fails.
>>>
>>> videobuf2_common: __vb2_queue_alloc: allocated 3 buffers, 1 plane(s) each
>>> videobuf2_common: __prepare_dmabuf: buffer for plane 0 changed
>>> videobuf2_common: __prepare_dmabuf: failed to map dmabuf for plane 0
>>> videobuf2_common: __buf_prepare: buffer preparation failed: -14
>>>
>>> The patch itself seems to be strighforward.
>>> It adds implementation of .vmap and .vunmap methods
>>> to 'struct dma_buf_ops udmabuf_ops'.
>>> .vmap method itself uses vm_map_ram() to map pages linearly
>>> into the kernel virtual address space.
>>> .vunmap removes mapping created earlier by .vmap.
>>> All locking and 'vmapping counting' is done in dma_buf.c
>>> so it seems to be redundant/unnecessary in .vmap/.vunmap.
>>>
>>> Signed-off-by: Lukasz Wiecaszek <lukasz.wiecaszek@gmail.com>
>>
>> If new patch version doesn't contain significant changes and you got
>> acks/reviews for the previous version, then you should add the given
>> acked-by and reviewed-by tags to the commit message by yourself.
>>
>> -- 
>> Best regards,
>> Dmitry
>>
> 
> I would like to thank you all for your patience and on the same time say
> sorry that I still cannot follow the process (although I have read
> 'submitting patches' chapter).

If you'll continue to contribute actively, you'll find things that
aren't documented at all. Don't worry about it, usually somebody will
tell you about what's missing. Just apply the new knowledge next time ;)
Christian König Nov. 17, 2022, 6:01 p.m. UTC | #4 
Am 17.11.22 um 18:32 schrieb Dmitry Osipenko:
> On 11/17/22 20:08, Lukasz Wiecaszek wrote:
>> On Thu, Nov 17, 2022 at 12:04:35PM +0300, Dmitry Osipenko wrote:
>>> Hi,
>>>
>>> On 11/17/22 07:58, Lukasz Wiecaszek wrote:
>>>> The reason behind that patch is associated with videobuf2 subsystem
>>>> (or more genrally with v4l2 framework) and user created
>>>> dma buffers (udmabuf). In some circumstances
>>>> when dealing with V4L2_MEMORY_DMABUF buffers videobuf2 subsystem
>>>> wants to use dma_buf_vmap() method on the attached dma buffer.
>>>> As udmabuf does not have .vmap operation implemented,
>>>> such dma_buf_vmap() natually fails.
>>>>
>>>> videobuf2_common: __vb2_queue_alloc: allocated 3 buffers, 1 plane(s) each
>>>> videobuf2_common: __prepare_dmabuf: buffer for plane 0 changed
>>>> videobuf2_common: __prepare_dmabuf: failed to map dmabuf for plane 0
>>>> videobuf2_common: __buf_prepare: buffer preparation failed: -14
>>>>
>>>> The patch itself seems to be strighforward.
>>>> It adds implementation of .vmap and .vunmap methods
>>>> to 'struct dma_buf_ops udmabuf_ops'.
>>>> .vmap method itself uses vm_map_ram() to map pages linearly
>>>> into the kernel virtual address space.
>>>> .vunmap removes mapping created earlier by .vmap.
>>>> All locking and 'vmapping counting' is done in dma_buf.c
>>>> so it seems to be redundant/unnecessary in .vmap/.vunmap.
>>>>
>>>> Signed-off-by: Lukasz Wiecaszek <lukasz.wiecaszek@gmail.com>
>>> If new patch version doesn't contain significant changes and you got
>>> acks/reviews for the previous version, then you should add the given
>>> acked-by and reviewed-by tags to the commit message by yourself.
>>>
>>> -- 
>>> Best regards,
>>> Dmitry
>>>
>> I would like to thank you all for your patience and on the same time say
>> sorry that I still cannot follow the process (although I have read
>> 'submitting patches' chapter).
> If you'll continue to contribute actively, you'll find things that
> aren't documented at all. Don't worry about it, usually somebody will
> tell you about what's missing. Just apply the new knowledge next time ;)

Yeah, it's more learning by doing. Especially I suspect you don't have 
commit rights to drm-misc-next (or do you want to upstream it through 
some other branch?), so as soon as nobody has any more objections ping 
Dmitry or me to push this.

Cheers,
Christian

PS: The Signed-of-by, Reviewed-by, Acked-by etc... lines are usually 
added in chronological order, e.g. your Signed-of-by line should always 
come first.
Lukasz Wiecaszek Nov. 18, 2022, 9:42 a.m. UTC | #5 
On Thu, Nov 17, 2022 at 07:01:05PM +0100, Christian König wrote:
> Am 17.11.22 um 18:32 schrieb Dmitry Osipenko:
> > On 11/17/22 20:08, Lukasz Wiecaszek wrote:
> > > On Thu, Nov 17, 2022 at 12:04:35PM +0300, Dmitry Osipenko wrote:
> > > > Hi,
> > > > 
> > > > On 11/17/22 07:58, Lukasz Wiecaszek wrote:
> > > > > The reason behind that patch is associated with videobuf2 subsystem
> > > > > (or more genrally with v4l2 framework) and user created
> > > > > dma buffers (udmabuf). In some circumstances
> > > > > when dealing with V4L2_MEMORY_DMABUF buffers videobuf2 subsystem
> > > > > wants to use dma_buf_vmap() method on the attached dma buffer.
> > > > > As udmabuf does not have .vmap operation implemented,
> > > > > such dma_buf_vmap() natually fails.
> > > > > 
> > > > > videobuf2_common: __vb2_queue_alloc: allocated 3 buffers, 1 plane(s) each
> > > > > videobuf2_common: __prepare_dmabuf: buffer for plane 0 changed
> > > > > videobuf2_common: __prepare_dmabuf: failed to map dmabuf for plane 0
> > > > > videobuf2_common: __buf_prepare: buffer preparation failed: -14
> > > > > 
> > > > > The patch itself seems to be strighforward.
> > > > > It adds implementation of .vmap and .vunmap methods
> > > > > to 'struct dma_buf_ops udmabuf_ops'.
> > > > > .vmap method itself uses vm_map_ram() to map pages linearly
> > > > > into the kernel virtual address space.
> > > > > .vunmap removes mapping created earlier by .vmap.
> > > > > All locking and 'vmapping counting' is done in dma_buf.c
> > > > > so it seems to be redundant/unnecessary in .vmap/.vunmap.
> > > > > 
> > > > > Signed-off-by: Lukasz Wiecaszek <lukasz.wiecaszek@gmail.com>
> > > > If new patch version doesn't contain significant changes and you got
> > > > acks/reviews for the previous version, then you should add the given
> > > > acked-by and reviewed-by tags to the commit message by yourself.
> > > > 
> > > > -- 
> > > > Best regards,
> > > > Dmitry
> > > > 
> > > I would like to thank you all for your patience and on the same time say
> > > sorry that I still cannot follow the process (although I have read
> > > 'submitting patches' chapter).
> > If you'll continue to contribute actively, you'll find things that
> > aren't documented at all. Don't worry about it, usually somebody will
> > tell you about what's missing. Just apply the new knowledge next time ;)
> 
> Yeah, it's more learning by doing. Especially I suspect you don't have
> commit rights to drm-misc-next (or do you want to upstream it through some
> other branch?), so as soon as nobody has any more objections ping Dmitry or
> me to push this.
> 
> Cheers,
> Christian
> 
> PS: The Signed-of-by, Reviewed-by, Acked-by etc... lines are usually added
> in chronological order, e.g. your Signed-of-by line should always come
> first.
> 
>
Thanks one more time. Funny thing, but at the very beginning I had
Signed-of-by as the first line. Then I looked at 'git log' and spoted
different order, so I change mine as well. Ahhh. But this chronological
order of course make sense. So if you feel ok with this 'out of order'
issue, please push/merge this commit. If not, please let me know. I
already submitted version 5 of that work. So if change is required, I
will prepare version 6.
diff mbox series

Patch

diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index 283816fbd72f..740d6e426ee9 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -13,6 +13,8 @@ 
 #include <linux/slab.h>
 #include <linux/udmabuf.h>
 #include <linux/hugetlb.h>
+#include <linux/vmalloc.h>
+#include <linux/iosys-map.h>
 
 static int list_limit = 1024;
 module_param(list_limit, int, 0644);
@@ -60,6 +62,30 @@  static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma)
 	return 0;
 }
 
+static int vmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)
+{
+	struct udmabuf *ubuf = buf->priv;
+	void *vaddr;
+
+	dma_resv_assert_held(buf->resv);
+
+	vaddr = vm_map_ram(ubuf->pages, ubuf->pagecount, -1);
+	if (!vaddr)
+		return -EINVAL;
+
+	iosys_map_set_vaddr(map, vaddr);
+	return 0;
+}
+
+static void vunmap_udmabuf(struct dma_buf *buf, struct iosys_map *map)
+{
+	struct udmabuf *ubuf = buf->priv;
+
+	dma_resv_assert_held(buf->resv);
+
+	vm_unmap_ram(map->vaddr, ubuf->pagecount);
+}
+
 static struct sg_table *get_sg_table(struct device *dev, struct dma_buf *buf,
 				     enum dma_data_direction direction)
 {
@@ -162,6 +188,8 @@  static const struct dma_buf_ops udmabuf_ops = {
 	.unmap_dma_buf	   = unmap_udmabuf,
 	.release	   = release_udmabuf,
 	.mmap		   = mmap_udmabuf,
+	.vmap		   = vmap_udmabuf,
+	.vunmap		   = vunmap_udmabuf,
 	.begin_cpu_access  = begin_cpu_udmabuf,
 	.end_cpu_access    = end_cpu_udmabuf,
 };