Create page_pool_alloc_netmem to be the mirror of page_pool_alloc.

This enables drivers that want currently use page_pool_alloc to
transition to netmem by converting the call sites to
page_pool_alloc_netmem.

Signed-off-by: Mina Almasry <almasrymina@google.com>
---
 include/net/page_pool/helpers.h | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h
index 793e6fd78bc5..8e548ff3044c 100644
--- a/include/net/page_pool/helpers.h
+++ b/include/net/page_pool/helpers.h
@@ -116,22 +116,22 @@ static inline struct page *page_pool_dev_alloc_frag(struct page_pool *pool,
 	return page_pool_alloc_frag(pool, offset, size, gfp);
 }
 
-static inline struct page *page_pool_alloc(struct page_pool *pool,
-					   unsigned int *offset,
-					   unsigned int *size, gfp_t gfp)
+static inline netmem_ref page_pool_alloc_netmem(struct page_pool *pool,
+						unsigned int *offset,
+						unsigned int *size, gfp_t gfp)
 {
 	unsigned int max_size = PAGE_SIZE << pool->p.order;
-	struct page *page;
+	netmem_ref netmem;
 
 	if ((*size << 1) > max_size) {
 		*size = max_size;
 		*offset = 0;
-		return page_pool_alloc_pages(pool, gfp);
+		return page_pool_alloc_netmems(pool, gfp);
 	}
 
-	page = page_pool_alloc_frag(pool, offset, *size, gfp);
-	if (unlikely(!page))
-		return NULL;
+	netmem = page_pool_alloc_frag_netmem(pool, offset, *size, gfp);
+	if (unlikely(!netmem))
+		return 0;
 
 	/* There is very likely not enough space for another fragment, so append
 	 * the remaining size to the current fragment to avoid truesize
@@ -142,7 +142,14 @@ static inline struct page *page_pool_alloc(struct page_pool *pool,
 		pool->frag_offset = max_size;
 	}
 
-	return page;
+	return netmem;
+}
+
+static inline struct page *page_pool_alloc(struct page_pool *pool,
+					   unsigned int *offset,
+					   unsigned int *size, gfp_t gfp)
+{
+	return netmem_to_page(page_pool_alloc_netmem(pool, offset, size, gfp));
 }
 
 /**
-- 
2.47.0.163.g1226f6d8fa-goog

On 2024/10/30 4:45, Mina Almasry wrote:
> Create page_pool_alloc_netmem to be the mirror of page_pool_alloc.
> 
> This enables drivers that want currently use page_pool_alloc to
> transition to netmem by converting the call sites to
> page_pool_alloc_netmem.

For old API, page_pool_alloc_pages() always return a whole page, and
page_pool_alloc() returns a whole page or a page fragment based on the
requested size.

For new netmem API, page_pool_alloc_netmems() always return a whole
netmem, and page_pool_alloc_netmem() returns a whole netmem or a netmem
fragment based on the requested size.

Isn't it a little odd that old and new are not following the same
pattern?

On Fri, Nov 1, 2024 at 4:14 AM Yunsheng Lin <linyunsheng@huawei.com> wrote:
>
> On 2024/10/30 4:45, Mina Almasry wrote:
> > Create page_pool_alloc_netmem to be the mirror of page_pool_alloc.
> >
> > This enables drivers that want currently use page_pool_alloc to
> > transition to netmem by converting the call sites to
> > page_pool_alloc_netmem.
>
> For old API, page_pool_alloc_pages() always return a whole page, and
> page_pool_alloc() returns a whole page or a page fragment based on the
> requested size.
>
> For new netmem API, page_pool_alloc_netmems() always return a whole
> netmem, and page_pool_alloc_netmem() returns a whole netmem or a netmem
> fragment based on the requested size.
>
> Isn't it a little odd that old and new are not following the same
> pattern?

Hi Yunsheng,

The intention is that page_pool_alloc_pages is mirrored by
page_pool_alloc_netmems.

And page_pool_alloc is mirrored by page_pool_alloc_netmem.

From your description, the behavior is the same for each function and
its mirror. What is the gap in the pattern that you see?

-- 
Thanks,
Mina

On 11/1/2024 9:10 PM, Mina Almasry wrote:

...

>>
>> Isn't it a little odd that old and new are not following the same
>> pattern?
> 
> Hi Yunsheng,
> 
> The intention is that page_pool_alloc_pages is mirrored by
> page_pool_alloc_netmems.
> 
> And page_pool_alloc is mirrored by page_pool_alloc_netmem.
> 
>>From your description, the behavior is the same for each function and
> its mirror. What is the gap in the pattern that you see?

I was mostly referring to the API naming pattern.

Isn't it better if page_pool_alloc is mirrored by netmem_pool_alloc and
netmem_pool_alloc_netmems is mirrored by page_pool_alloc_pages() from
API naming prespective?

And maybe page_pool_alloc_frag can be mirrored by netmem_pool_alloc_frag
in the future?

Also, it would be good to update Documentation/networking/page_pool.rst
for those new netmem APIs, or create a new doc file for them.

>

On Sun, Nov 3, 2024 at 6:35 AM Yunsheng Lin <yunshenglin0825@gmail.com> wrote:
>
> On 11/1/2024 9:10 PM, Mina Almasry wrote:
>
> ...
>
> >>
> >> Isn't it a little odd that old and new are not following the same
> >> pattern?
> >
> > Hi Yunsheng,
> >
> > The intention is that page_pool_alloc_pages is mirrored by
> > page_pool_alloc_netmems.
> >
> > And page_pool_alloc is mirrored by page_pool_alloc_netmem.
> >
> >>From your description, the behavior is the same for each function and
> > its mirror. What is the gap in the pattern that you see?
>
> I was mostly referring to the API naming pattern.
>
> Isn't it better if page_pool_alloc is mirrored by netmem_pool_alloc and
> netmem_pool_alloc_netmems is mirrored by page_pool_alloc_pages() from
> API naming prespective?
>

I've been treating the page_pool_* prefix to all the page_pool
functions as constant in all the renames so far. I replace 'page' with
'netmem' when available, or add a _netmem postfix when available.

> And maybe page_pool_alloc_frag can be mirrored by netmem_pool_alloc_frag
> in the future?
>
> Also, it would be good to update Documentation/networking/page_pool.rst
> for those new netmem APIs, or create a new doc file for them.
>

Heard. I do have an action item to update the docs. Currently, outside
of drivers immediately looking to immediately adopt devmem tcp, there
is no need yet to use the netmem APIs, but I do hope to make them more
widespread (and perhaps deprecate the page APIs when it's time to do
so).

-- 
Thanks,
Mina