[PATCH RFC net-next v2 1/7] net: skbuff: don't include <net/page_pool.h> to <linux/skbuff.h>

From: Alexander Lobakin
Date: Fri Jul 14 2023 - 13:10:32 EST

Currently, touching <net/page_pool.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.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.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(). It's used also in napi_frag_unref() ->
{__,}skb_frag_unref(), so no `static` unfortunately. Maybe next time.
Now, after a few include fixes in the drivers, touching page_pool.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>
---
drivers/net/ethernet/engleder/tsnep_main.c | 1 +
drivers/net/ethernet/freescale/fec_main.c | 1 +
.../marvell/octeontx2/nic/otx2_common.c | 1 +
.../ethernet/marvell/octeontx2/nic/otx2_pf.c | 1 +
.../ethernet/mellanox/mlx5/core/en/params.c | 1 +
.../net/ethernet/mellanox/mlx5/core/en/xdp.c | 1 +
drivers/net/wireless/mediatek/mt76/mt76.h | 1 +
include/linux/skbuff.h | 3 +-
include/net/page_pool.h | 2 -
net/core/page_pool.c | 39 -------------------
net/core/skbuff.c | 39 +++++++++++++++++++
11 files changed, 48 insertions(+), 42 deletions(-)

diff --git a/drivers/net/ethernet/engleder/tsnep_main.c b/drivers/net/ethernet/engleder/tsnep_main.c
index 84751bb303a6..6222aaa5157f 100644
--- a/drivers/net/ethernet/engleder/tsnep_main.c
+++ b/drivers/net/ethernet/engleder/tsnep_main.c
@@ -28,6 +28,7 @@
#include <linux/iopoll.h>
#include <linux/bpf.h>
#include <linux/bpf_trace.h>
+#include <net/page_pool.h>
#include <net/xdp_sock_drv.h>

#define TSNEP_RX_OFFSET (max(NET_SKB_PAD, XDP_PACKET_HEADROOM) + NET_IP_ALIGN)
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index 1b990a486059..cfc07f012254 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -38,6 +38,7 @@
#include <linux/in.h>
#include <linux/ip.h>
#include <net/ip.h>
+#include <net/page_pool.h>
#include <net/selftests.h>
#include <net/tso.h>
#include <linux/tcp.h>
diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
index a5d03583bf79..d17a0ebc9036 100644
--- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
+++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
@@ -7,6 +7,7 @@

#include <linux/interrupt.h>
#include <linux/pci.h>
+#include <net/page_pool.h>
#include <net/tso.h>
#include <linux/bitfield.h>

diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c
index fe8ea4e531b7..7eca434a0550 100644
--- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c
+++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c
@@ -16,6 +16,7 @@
#include <linux/bpf.h>
#include <linux/bpf_trace.h>
#include <linux/bitfield.h>
+#include <net/page_pool.h>

#include "otx2_reg.h"
#include "otx2_common.h"
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/params.c b/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
index 5ce28ff7685f..0f152f14165b 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
@@ -6,6 +6,7 @@
#include "en/port.h"
#include "en_accel/en_accel.h"
#include "en_accel/ipsec.h"
+#include <net/page_pool.h>
#include <net/xdp_sock_drv.h>

static u8 mlx5e_mpwrq_min_page_shift(struct mlx5_core_dev *mdev)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
index 40589cebb773..16038c23b7d8 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
@@ -35,6 +35,7 @@
#include "en/xdp.h"
#include "en/params.h"
#include <linux/bitfield.h>
+#include <net/page_pool.h>

int mlx5e_xdp_max_mtu(struct mlx5e_params *params, struct mlx5e_xsk_param *xsk)
{
diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h b/drivers/net/wireless/mediatek/mt76/mt76.h
index 6b07b8fafec2..95c16f11d156 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76.h
+++ b/drivers/net/wireless/mediatek/mt76/mt76.h
@@ -15,6 +15,7 @@
#include <linux/average.h>
#include <linux/soc/mediatek/mtk_wed.h>
#include <net/mac80211.h>
+#include <net/page_pool.h>
#include "util.h"
#include "testmode.h"

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 91ed66952580..f76d172ed262 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.h>
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
#include <linux/netfilter/nf_conntrack_common.h>
#endif
@@ -3423,6 +3422,8 @@ static inline void skb_frag_ref(struct sk_buff *skb, int f)
__skb_frag_ref(&skb_shinfo(skb)->frags[f]);
}

+bool page_pool_return_skb_page(struct page *page, bool napi_safe);
+
static inline void
napi_frag_unref(skb_frag_t *frag, bool recycle, bool napi_safe)
{
diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index 2b7db9992fc0..829dc1f8ba6b 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -307,8 +307,6 @@ inline enum dma_data_direction page_pool_get_dma_dir(struct page_pool *pool)
return pool->p.dma_dir;
}

-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 985ccaffc06a..09d76e37ac69 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -913,42 +913,3 @@ 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 ea9c09b4b927..4de280c454e4 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -879,6 +879,45 @@ static void skb_clone_fraglist(struct sk_buff *skb)
skb_get(list);
}

+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);
+
static bool skb_pp_recycle(struct sk_buff *skb, void *data, bool napi_safe)
{
if (!IS_ENABLED(CONFIG_PAGE_POOL) || !skb->pp_recycle)
--
2.41.0