[PATCH net-next v2 2/6] net: skbuff: don't include <net/page_pool/types.h> to <linux/skbuff.h>

From: Alexander Lobakin
Date: Thu Aug 03 2023 - 12:40:54 EST


Currently, touching <net/page_pool/types.h> triggers a rebuild of more
than half of the kernel. That's because it's included in
<linux/skbuff.h>. And each new include to page_pool/types.h adds more
[useless] data for the toolchain to process per each source file from
that pile.

In commit 6a5bcd84e886 ("page_pool: Allow drivers to hint on SKB
recycling"), Matteo included it to be able to call a couple of functions
defined there. Then, in commit 57f05bc2ab24 ("page_pool: keep pp info as
long as page pool owns the page") one of the calls was removed, so only
one was left. It's the call to page_pool_return_skb_page() in
napi_frag_unref(). The function is external and doesn't have any
dependencies. Having very niche page_pool_types.h included only for that
looks like an overkill.

As %PP_SIGNATURE is not local to page_pool.c (was only in the
early submissions), nothing holds this function there. Teleport
page_pool_return_skb_page() to skbuff.c, just next to the main consumer,
skb_pp_recycle(), and rename it to napi_pp_put_page(), as it doesn't
work with skbs at all and the former name tells nothing. The #if guards
here are only to not compile and have it in the vmlinux when not needed
-- both call sites are already guarded.
Now, touching page_pool_types.h only triggers rebuilding of the drivers
using it and a couple of core networking files.

Suggested-by: Jakub Kicinski <kuba@xxxxxxxxxx> # make skbuff.h less heavy
Suggested-by: Alexander Duyck <alexanderduyck@xxxxxx> # move to skbuff.c
Signed-off-by: Alexander Lobakin <aleksander.lobakin@xxxxxxxxx>
---
include/linux/skbuff.h | 5 ++--
include/net/page_pool/types.h | 2 --
net/core/page_pool.c | 39 ------------------------------
net/core/skbuff.c | 45 +++++++++++++++++++++++++++++++++--
4 files changed, 46 insertions(+), 45 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 888e3d7e74c1..aa57e2eca33b 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -32,7 +32,6 @@
#include <linux/if_packet.h>
#include <linux/llist.h>
#include <net/flow.h>
-#include <net/page_pool/types.h>
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
#include <linux/netfilter/nf_conntrack_common.h>
#endif
@@ -3421,13 +3420,15 @@ static inline void skb_frag_ref(struct sk_buff *skb, int f)
__skb_frag_ref(&skb_shinfo(skb)->frags[f]);
}

+bool napi_pp_put_page(struct page *page, bool napi_safe);
+
static inline void
napi_frag_unref(skb_frag_t *frag, bool recycle, bool napi_safe)
{
struct page *page = skb_frag_page(frag);

#ifdef CONFIG_PAGE_POOL
- if (recycle && page_pool_return_skb_page(page, napi_safe))
+ if (recycle && napi_pp_put_page(page, napi_safe))
return;
#endif
put_page(page);
diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
index 4a0270291deb..c7aef6c75935 100644
--- a/include/net/page_pool/types.h
+++ b/include/net/page_pool/types.h
@@ -156,8 +156,6 @@ struct page_pool {
struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
struct page *page_pool_alloc_frag(struct page_pool *pool, unsigned int *offset,
unsigned int size, gfp_t gfp);
-bool page_pool_return_skb_page(struct page *page, bool napi_safe);
-
struct page_pool *page_pool_create(const struct page_pool_params *params);

struct xdp_mem_info;
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 2a75f61264c5..7a23ca6b1124 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -906,42 +906,3 @@ void page_pool_update_nid(struct page_pool *pool, int new_nid)
}
}
EXPORT_SYMBOL(page_pool_update_nid);
-
-bool page_pool_return_skb_page(struct page *page, bool napi_safe)
-{
- struct napi_struct *napi;
- struct page_pool *pp;
- bool allow_direct;
-
- page = compound_head(page);
-
- /* page->pp_magic is OR'ed with PP_SIGNATURE after the allocation
- * in order to preserve any existing bits, such as bit 0 for the
- * head page of compound page and bit 1 for pfmemalloc page, so
- * mask those bits for freeing side when doing below checking,
- * and page_is_pfmemalloc() is checked in __page_pool_put_page()
- * to avoid recycling the pfmemalloc page.
- */
- if (unlikely((page->pp_magic & ~0x3UL) != PP_SIGNATURE))
- return false;
-
- pp = page->pp;
-
- /* Allow direct recycle if we have reasons to believe that we are
- * in the same context as the consumer would run, so there's
- * no possible race.
- */
- napi = READ_ONCE(pp->p.napi);
- allow_direct = napi_safe && napi &&
- READ_ONCE(napi->list_owner) == smp_processor_id();
-
- /* Driver set this to memory recycling info. Reset it on recycle.
- * This will *not* work for NIC using a split-page memory model.
- * The page will be returned to the pool here regardless of the
- * 'flipped' fragment being in use or not.
- */
- page_pool_put_full_page(pp, page, allow_direct);
-
- return true;
-}
-EXPORT_SYMBOL(page_pool_return_skb_page);
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index d3bed964123c..acc5844a0de1 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -73,7 +73,7 @@
#include <net/mpls.h>
#include <net/mptcp.h>
#include <net/mctp.h>
-#include <net/page_pool/types.h>
+#include <net/page_pool/helpers.h>
#include <net/dropreason.h>

#include <linux/uaccess.h>
@@ -879,11 +879,52 @@ static void skb_clone_fraglist(struct sk_buff *skb)
skb_get(list);
}

+#if IS_ENABLED(CONFIG_PAGE_POOL)
+bool napi_pp_put_page(struct page *page, bool napi_safe)
+{
+ struct napi_struct *napi;
+ struct page_pool *pp;
+ bool allow_direct;
+
+ page = compound_head(page);
+
+ /* page->pp_magic is OR'ed with PP_SIGNATURE after the allocation
+ * in order to preserve any existing bits, such as bit 0 for the
+ * head page of compound page and bit 1 for pfmemalloc page, so
+ * mask those bits for freeing side when doing below checking,
+ * and page_is_pfmemalloc() is checked in __page_pool_put_page()
+ * to avoid recycling the pfmemalloc page.
+ */
+ if (unlikely((page->pp_magic & ~0x3UL) != PP_SIGNATURE))
+ return false;
+
+ pp = page->pp;
+
+ /* Allow direct recycle if we have reasons to believe that we are
+ * in the same context as the consumer would run, so there's
+ * no possible race.
+ */
+ napi = READ_ONCE(pp->p.napi);
+ allow_direct = napi_safe && napi &&
+ READ_ONCE(napi->list_owner) == smp_processor_id();
+
+ /* Driver set this to memory recycling info. Reset it on recycle.
+ * This will *not* work for NIC using a split-page memory model.
+ * The page will be returned to the pool here regardless of the
+ * 'flipped' fragment being in use or not.
+ */
+ page_pool_put_full_page(pp, page, allow_direct);
+
+ return true;
+}
+EXPORT_SYMBOL(napi_pp_put_page);
+#endif
+
static bool skb_pp_recycle(struct sk_buff *skb, void *data, bool napi_safe)
{
if (!IS_ENABLED(CONFIG_PAGE_POOL) || !skb->pp_recycle)
return false;
- return page_pool_return_skb_page(virt_to_page(data), napi_safe);
+ return napi_pp_put_page(virt_to_page(data), napi_safe);
}

static void skb_kfree_head(void *head, unsigned int end_offset)
--
2.41.0