diff mbox series

[v1,04/15] net: page_pool: create hooks for custom page providers

Message ID 20241007221603.1703699-5-dw@davidwei.uk (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series io_uring zero copy rx | expand

Checks

Context Check Description
netdev/tree_selection success Guessing tree name failed - patch did not apply, async

Commit Message

David Wei Oct. 7, 2024, 10:15 p.m. UTC 
From: Jakub Kicinski <kuba@kernel.org>

The page providers which try to reuse the same pages will
need to hold onto the ref, even if page gets released from
the pool - as in releasing the page from the pp just transfers
the "ownership" reference from pp to the provider, and provider
will wait for other references to be gone before feeding this
page back into the pool.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[Pavel] Rebased, renamed callback, +converted devmem
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David Wei <dw@davidwei.uk>
---
 include/net/page_pool/types.h |  9 +++++++++
 net/core/devmem.c             | 13 ++++++++++++-
 net/core/devmem.h             |  2 ++
 net/core/page_pool.c          | 17 +++++++++--------
 4 files changed, 32 insertions(+), 9 deletions(-)

Comments

Mina Almasry Oct. 9, 2024, 8:49 p.m. UTC | #1 
On Mon, Oct 7, 2024 at 3:16 PM David Wei <dw@davidwei.uk> wrote:
>
> From: Jakub Kicinski <kuba@kernel.org>
>
> The page providers which try to reuse the same pages will
> need to hold onto the ref, even if page gets released from
> the pool - as in releasing the page from the pp just transfers
> the "ownership" reference from pp to the provider, and provider
> will wait for other references to be gone before feeding this
> page back into the pool.
>
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> [Pavel] Rebased, renamed callback, +converted devmem
> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> Signed-off-by: David Wei <dw@davidwei.uk>

Likely needs a Cc: Christoph Hellwig <hch@lst.de>, given previous
feedback to this patch?

But that's going to run into the same feedback again. You don't want
to do this without the ops again?
Pavel Begunkov Oct. 9, 2024, 10:02 p.m. UTC | #2 
On 10/9/24 21:49, Mina Almasry wrote:
> On Mon, Oct 7, 2024 at 3:16 PM David Wei <dw@davidwei.uk> wrote:
>>
>> From: Jakub Kicinski <kuba@kernel.org>
>>
>> The page providers which try to reuse the same pages will
>> need to hold onto the ref, even if page gets released from
>> the pool - as in releasing the page from the pp just transfers
>> the "ownership" reference from pp to the provider, and provider
>> will wait for other references to be gone before feeding this
>> page back into the pool.
>>
>> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
>> [Pavel] Rebased, renamed callback, +converted devmem
>> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
>> Signed-off-by: David Wei <dw@davidwei.uk>
> 
> Likely needs a Cc: Christoph Hellwig <hch@lst.de>, given previous
> feedback to this patch?

I wouldn't bother, I don't believe it's done in good faith.

> But that's going to run into the same feedback again. You don't want
> to do this without the ops again?

Well, the guy sprinkles nacks as confetti, it's getting hard
to take it seriously. It's a net change, I'll leave it to the
net maintainers to judge.
diff mbox series

Patch

diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
index c022c410abe3..8a35fe474adb 100644
--- a/include/net/page_pool/types.h
+++ b/include/net/page_pool/types.h
@@ -152,8 +152,16 @@  struct page_pool_stats {
  */
 #define PAGE_POOL_FRAG_GROUP_ALIGN	(4 * sizeof(long))
 
+struct memory_provider_ops {
+	netmem_ref (*alloc_netmems)(struct page_pool *pool, gfp_t gfp);
+	bool (*release_netmem)(struct page_pool *pool, netmem_ref netmem);
+	int (*init)(struct page_pool *pool);
+	void (*destroy)(struct page_pool *pool);
+};
+
 struct pp_memory_provider_params {
 	void *mp_priv;
+	const struct memory_provider_ops *mp_ops;
 };
 
 struct page_pool {
@@ -215,6 +223,7 @@  struct page_pool {
 	struct ptr_ring ring;
 
 	void *mp_priv;
+	const struct memory_provider_ops *mp_ops;
 
 #ifdef CONFIG_PAGE_POOL_STATS
 	/* recycle stats are per-cpu to avoid locking */
diff --git a/net/core/devmem.c b/net/core/devmem.c
index 5c10cf0e2a18..83d13eb441b6 100644
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -117,6 +117,7 @@  void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding)
 		WARN_ON(rxq->mp_params.mp_priv != binding);
 
 		rxq->mp_params.mp_priv = NULL;
+		rxq->mp_params.mp_ops = NULL;
 
 		rxq_idx = get_netdev_rx_queue_index(rxq);
 
@@ -142,7 +143,7 @@  int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
 	}
 
 	rxq = __netif_get_rx_queue(dev, rxq_idx);
-	if (rxq->mp_params.mp_priv) {
+	if (rxq->mp_params.mp_ops) {
 		NL_SET_ERR_MSG(extack, "designated queue already memory provider bound");
 		return -EEXIST;
 	}
@@ -160,6 +161,7 @@  int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
 		return err;
 
 	rxq->mp_params.mp_priv = binding;
+	rxq->mp_params.mp_ops = &dmabuf_devmem_ops;
 
 	err = netdev_rx_queue_restart(dev, rxq_idx);
 	if (err)
@@ -169,6 +171,7 @@  int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
 
 err_xa_erase:
 	rxq->mp_params.mp_priv = NULL;
+	rxq->mp_params.mp_ops = NULL;
 	xa_erase(&binding->bound_rxqs, xa_idx);
 
 	return err;
@@ -388,3 +391,11 @@  bool mp_dmabuf_devmem_release_page(struct page_pool *pool, netmem_ref netmem)
 	/* We don't want the page pool put_page()ing our net_iovs. */
 	return false;
 }
+
+const struct memory_provider_ops dmabuf_devmem_ops = {
+	.init			= mp_dmabuf_devmem_init,
+	.destroy		= mp_dmabuf_devmem_destroy,
+	.alloc_netmems		= mp_dmabuf_devmem_alloc_netmems,
+	.release_netmem		= mp_dmabuf_devmem_release_page,
+};
+EXPORT_SYMBOL(dmabuf_devmem_ops);
diff --git a/net/core/devmem.h b/net/core/devmem.h
index 12b14377ed3f..fbf7ec9a62cb 100644
--- a/net/core/devmem.h
+++ b/net/core/devmem.h
@@ -88,6 +88,8 @@  static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov)
 
 #if defined(CONFIG_NET_DEVMEM)
 
+extern const struct memory_provider_ops dmabuf_devmem_ops;
+
 void __net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding *binding);
 struct net_devmem_dmabuf_binding *
 net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index a813d30d2135..c21c5b9edc68 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -284,10 +284,11 @@  static int page_pool_init(struct page_pool *pool,
 		rxq = __netif_get_rx_queue(pool->slow.netdev,
 					   pool->slow.queue_idx);
 		pool->mp_priv = rxq->mp_params.mp_priv;
+		pool->mp_ops = rxq->mp_params.mp_ops;
 	}
 
-	if (pool->mp_priv) {
-		err = mp_dmabuf_devmem_init(pool);
+	if (pool->mp_ops) {
+		err = pool->mp_ops->init(pool);
 		if (err) {
 			pr_warn("%s() mem-provider init failed %d\n", __func__,
 				err);
@@ -584,8 +585,8 @@  netmem_ref page_pool_alloc_netmem(struct page_pool *pool, gfp_t gfp)
 		return netmem;
 
 	/* Slow-path: cache empty, do real allocation */
-	if (static_branch_unlikely(&page_pool_mem_providers) && pool->mp_priv)
-		netmem = mp_dmabuf_devmem_alloc_netmems(pool, gfp);
+	if (static_branch_unlikely(&page_pool_mem_providers) && pool->mp_ops)
+		netmem = pool->mp_ops->alloc_netmems(pool, gfp);
 	else
 		netmem = __page_pool_alloc_pages_slow(pool, gfp);
 	return netmem;
@@ -676,8 +677,8 @@  void page_pool_return_page(struct page_pool *pool, netmem_ref netmem)
 	bool put;
 
 	put = true;
-	if (static_branch_unlikely(&page_pool_mem_providers) && pool->mp_priv)
-		put = mp_dmabuf_devmem_release_page(pool, netmem);
+	if (static_branch_unlikely(&page_pool_mem_providers) && pool->mp_ops)
+		put = pool->mp_ops->release_netmem(pool, netmem);
 	else
 		__page_pool_release_page_dma(pool, netmem);
 
@@ -1010,8 +1011,8 @@  static void __page_pool_destroy(struct page_pool *pool)
 	page_pool_unlist(pool);
 	page_pool_uninit(pool);
 
-	if (pool->mp_priv) {
-		mp_dmabuf_devmem_destroy(pool);
+	if (pool->mp_ops) {
+		pool->mp_ops->destroy(pool);
 		static_branch_dec(&page_pool_mem_providers);
 	}