netdev - [PATCH 02/12] xfrm: Skip redundant replay recheck for the hardware offload path

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Message-ID: <20251118092610.2223552-3-steffen.klassert@secunet.com>
Date: Tue, 18 Nov 2025 10:25:39 +0100
From: Steffen Klassert <steffen.klassert@...unet.com>
To: David Miller <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>
CC: Herbert Xu <herbert@...dor.apana.org.au>, Steffen Klassert
	<steffen.klassert@...unet.com>, <netdev@...r.kernel.org>
Subject: [PATCH 02/12] xfrm: Skip redundant replay recheck for the hardware offload path

From: Jianbo Liu <jianbol@...dia.com>

The xfrm_replay_recheck() function was introduced to handle the issues
arising from asynchronous crypto algorithms.

The crypto offload path is now effectively synchronous, as it holds
the state lock throughout its operation. This eliminates the race
condition, making the recheck an unnecessary overhead. This patch
improves performance by skipping the redundant call when
crypto_done is true.

Additionally, the sequence number assignment is moved to an earlier
point in the function. This improves performance by reducing lock
contention and places the logic at a more appropriate point, as the
full sequence number (including the higher-order bits) can be
determined as soon as the packet is received.

Signed-off-by: Jianbo Liu <jianbol@...dia.com>
Reviewed-by: Cosmin Ratiu <cratiu@...dia.com>
Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
---
 net/xfrm/xfrm_input.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 257935cbd221..4ed346e682c7 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -546,7 +546,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 			nexthdr = x->type_offload->input_tail(x, skb);
 		}
 
-		goto lock;
+		goto process;
 	}
 
 	family = XFRM_SPI_SKB_CB(skb)->family;
@@ -614,7 +614,12 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 			goto drop;
 		}
 
-lock:
+process:
+		seq_hi = htonl(xfrm_replay_seqhi(x, seq));
+
+		XFRM_SKB_CB(skb)->seq.input.low = seq;
+		XFRM_SKB_CB(skb)->seq.input.hi = seq_hi;
+
 		spin_lock(&x->lock);
 
 		if (unlikely(x->km.state != XFRM_STATE_VALID)) {
@@ -646,11 +651,6 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 			goto drop_unlock;
 		}
 
-		seq_hi = htonl(xfrm_replay_seqhi(x, seq));
-
-		XFRM_SKB_CB(skb)->seq.input.low = seq;
-		XFRM_SKB_CB(skb)->seq.input.hi = seq_hi;
-
 		if (!crypto_done) {
 			spin_unlock(&x->lock);
 			dev_hold(skb->dev);
@@ -676,7 +676,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
 		/* only the first xfrm gets the encap type */
 		encap_type = 0;
 
-		if (xfrm_replay_recheck(x, skb, seq)) {
+		if (!crypto_done && xfrm_replay_recheck(x, skb, seq)) {
 			XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATESEQERROR);
 			goto drop_unlock;
 		}
-- 
2.43.0