[PATCH net-next v2] xsk: add indirect call for xsk_destruct_skb

[Jason Xing <kerneljasonxing@gmail.com>]

From: Jason Xing <kernelxing@tencent.com>

Since Eric proposed an idea about adding indirect call for UDP and
managed to see a huge improvement[1], the same situation can also be
applied in xsk scenario.

This patch adds an indirect call for xsk and helps current copy mode
improve the performance by around 1% stably which was observed with
IXGBE at 10Gb/sec loaded. If the throughput grows, the positive effect
will be magnified. I applied this patch on top of batch xmit series[2],
and was able to see <5% improvement from our internal application
which is a little bit unstable though.

Use INDIRECT wrappers to keep xsk_destruct_skb static as it used to
be when the mitigation config is off.

[1]: https://lore.kernel.org/netdev/20251006193103.2684156-2-edumazet@google.com/
[2]: https://lore.kernel.org/all/20251021131209.41491-1-kerneljasonxing@gmail.com/

Suggested-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
v2
Link: https://lore.kernel.org/all/20251023085843.25619-1-kerneljasonxing@gmail.com/
1. use INDIRECT helpers (Alexander)
---
 include/net/xdp_sock.h | 7 +++++++
 net/core/skbuff.c      | 8 +++++---
 net/xdp/xsk.c          | 3 ++-
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index ce587a225661..23e8861e8b25 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -125,6 +125,7 @@ struct xsk_tx_metadata_ops {
 int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp);
 int __xsk_map_redirect(struct xdp_sock *xs, struct xdp_buff *xdp);
 void __xsk_map_flush(struct list_head *flush_list);
+INDIRECT_CALLABLE_DECLARE(void xsk_destruct_skb(struct sk_buff *));
 
 /**
  *  xsk_tx_metadata_to_compl - Save enough relevant metadata information
@@ -218,6 +219,12 @@ static inline void __xsk_map_flush(struct list_head *flush_list)
 {
 }
 
+#ifdef CONFIG_MITIGATION_RETPOLINE
+static inline void xsk_destruct_skb(struct sk_buff *skb)
+{
+}
+#endif
+
 static inline void xsk_tx_metadata_to_compl(struct xsk_tx_metadata *meta,
 					    struct xsk_tx_metadata_compl *compl)
 {
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 5b4bc8b1c7d5..00ea38248bd6 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -81,6 +81,7 @@
 #include <net/page_pool/helpers.h>
 #include <net/psp/types.h>
 #include <net/dropreason.h>
+#include <net/xdp_sock.h>
 
 #include <linux/uaccess.h>
 #include <trace/events/skb.h>
@@ -1140,12 +1141,13 @@ void skb_release_head_state(struct sk_buff *skb)
 	if (skb->destructor) {
 		DEBUG_NET_WARN_ON_ONCE(in_hardirq());
 #ifdef CONFIG_INET
-		INDIRECT_CALL_3(skb->destructor,
+		INDIRECT_CALL_4(skb->destructor,
 				tcp_wfree, __sock_wfree, sock_wfree,
+				xsk_destruct_skb,
 				skb);
 #else
-		INDIRECT_CALL_1(skb->destructor,
-				sock_wfree,
+		INDIRECT_CALL_2(skb->destructor,
+				sock_wfree, xsk_destruct_skb,
 				skb);
 
 #endif
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 7b0c68a70888..9451b090db16 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -605,7 +605,8 @@ static u32 xsk_get_num_desc(struct sk_buff *skb)
 	return XSKCB(skb)->num_descs;
 }
 
-static void xsk_destruct_skb(struct sk_buff *skb)
+INDIRECT_CALLABLE_SCOPE
+void xsk_destruct_skb(struct sk_buff *skb)
 {
 	struct xsk_tx_metadata_compl *compl = &skb_shinfo(skb)->xsk_meta;
 
-- 
2.41.3