[PATCH v5 net-next v5 1/6] net: move skb_gro_receive_list from udp to core

[PATCH v5 net-next v5 1/6] net: move skb_gro_receive_list from udp to core

[Felix Fietkau]

This helper function will be used for TCP fraglist GRO support

Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 include/net/gro.h      |  1 +
 net/core/gro.c         | 27 +++++++++++++++++++++++++++
 net/ipv4/udp_offload.c | 27 ---------------------------
 3 files changed, 28 insertions(+), 27 deletions(-)

diff --git a/include/net/gro.h b/include/net/gro.h
index 50f1e403dbbb..ca8e4b3de044 100644
--- a/include/net/gro.h
+++ b/include/net/gro.h
@@ -429,6 +429,7 @@ static inline __wsum ip6_gro_compute_pseudo(const struct sk_buff *skb,
 }
 
 int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb);
+int skb_gro_receive_list(struct sk_buff *p, struct sk_buff *skb);
 
 /* Pass the currently batched GRO_NORMAL SKBs up to the stack. */
 static inline void gro_normal_list(struct napi_struct *napi)
diff --git a/net/core/gro.c b/net/core/gro.c
index 2459ab697f7f..268c6c826d09 100644
--- a/net/core/gro.c
+++ b/net/core/gro.c
@@ -231,6 +231,33 @@ int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
 	return 0;
 }
 
+int skb_gro_receive_list(struct sk_buff *p, struct sk_buff *skb)
+{
+	if (unlikely(p->len + skb->len >= 65536))
+		return -E2BIG;
+
+	if (NAPI_GRO_CB(p)->last == p)
+		skb_shinfo(p)->frag_list = skb;
+	else
+		NAPI_GRO_CB(p)->last->next = skb;
+
+	skb_pull(skb, skb_gro_offset(skb));
+
+	NAPI_GRO_CB(p)->last = skb;
+	NAPI_GRO_CB(p)->count++;
+	p->data_len += skb->len;
+
+	/* sk ownership - if any - completely transferred to the aggregated packet */
+	skb->destructor = NULL;
+	skb->sk = NULL;
+	p->truesize += skb->truesize;
+	p->len += skb->len;
+
+	NAPI_GRO_CB(skb)->same_flow = 1;
+
+	return 0;
+}
+
 
 static void napi_gro_complete(struct napi_struct *napi, struct sk_buff *skb)
 {
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index 3498dd1d0694..a3cd546a1aea 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -433,33 +433,6 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
 	return segs;
 }
 
-static int skb_gro_receive_list(struct sk_buff *p, struct sk_buff *skb)
-{
-	if (unlikely(p->len + skb->len >= 65536))
-		return -E2BIG;
-
-	if (NAPI_GRO_CB(p)->last == p)
-		skb_shinfo(p)->frag_list = skb;
-	else
-		NAPI_GRO_CB(p)->last->next = skb;
-
-	skb_pull(skb, skb_gro_offset(skb));
-
-	NAPI_GRO_CB(p)->last = skb;
-	NAPI_GRO_CB(p)->count++;
-	p->data_len += skb->len;
-
-	/* sk ownership - if any - completely transferred to the aggregated packet */
-	skb->destructor = NULL;
-	skb->sk = NULL;
-	p->truesize += skb->truesize;
-	p->len += skb->len;
-
-	NAPI_GRO_CB(skb)->same_flow = 1;
-
-	return 0;
-}
-
 
 #define UDP_GRO_CNT_MAX 64
 static struct sk_buff *udp_gro_receive_segment(struct list_head *head,
-- 
2.44.0

Re: [PATCH v5 net-next v5 1/6] net: move skb_gro_receive_list from udp to core

[David Ahern]

On 5/2/24 2:44 AM, Felix Fietkau wrote:
> This helper function will be used for TCP fraglist GRO support
> 
> Acked-by: Paolo Abeni <pabeni@redhat.com>
> Reviewed-by: Eric Dumazet <edumazet@google.com>
> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> ---
>  include/net/gro.h      |  1 +
>  net/core/gro.c         | 27 +++++++++++++++++++++++++++
>  net/ipv4/udp_offload.c | 27 ---------------------------
>  3 files changed, 28 insertions(+), 27 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>

[PATCH v5 net-next v5 2/6] net: add support for segmenting TCP fraglist GSO packets

[Felix Fietkau]

Preparation for adding TCP fraglist GRO support. It expects packets to be
combined in a similar way as UDP fraglist GSO packets.
For IPv4 packets, NAT is handled in the same way as UDP fraglist GSO.

Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 net/ipv4/tcp_offload.c   | 67 ++++++++++++++++++++++++++++++++++++++++
 net/ipv6/tcpv6_offload.c | 58 ++++++++++++++++++++++++++++++++++
 2 files changed, 125 insertions(+)

diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index fab0973f995b..affd4ed28cfe 100644
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -28,6 +28,70 @@ static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq,
 	}
 }
 
+static void __tcpv4_gso_segment_csum(struct sk_buff *seg,
+				     __be32 *oldip, __be32 newip,
+				     __be16 *oldport, __be16 newport)
+{
+	struct tcphdr *th;
+	struct iphdr *iph;
+
+	if (*oldip == newip && *oldport == newport)
+		return;
+
+	th = tcp_hdr(seg);
+	iph = ip_hdr(seg);
+
+	inet_proto_csum_replace4(&th->check, seg, *oldip, newip, true);
+	inet_proto_csum_replace2(&th->check, seg, *oldport, newport, false);
+	*oldport = newport;
+
+	csum_replace4(&iph->check, *oldip, newip);
+	*oldip = newip;
+}
+
+static struct sk_buff *__tcpv4_gso_segment_list_csum(struct sk_buff *segs)
+{
+	const struct tcphdr *th;
+	const struct iphdr *iph;
+	struct sk_buff *seg;
+	struct tcphdr *th2;
+	struct iphdr *iph2;
+
+	seg = segs;
+	th = tcp_hdr(seg);
+	iph = ip_hdr(seg);
+	th2 = tcp_hdr(seg->next);
+	iph2 = ip_hdr(seg->next);
+
+	if (!(*(const u32 *)&th->source ^ *(const u32 *)&th2->source) &&
+	    iph->daddr == iph2->daddr && iph->saddr == iph2->saddr)
+		return segs;
+
+	while ((seg = seg->next)) {
+		th2 = tcp_hdr(seg);
+		iph2 = ip_hdr(seg);
+
+		__tcpv4_gso_segment_csum(seg,
+					 &iph2->saddr, iph->saddr,
+					 &th2->source, th->source);
+		__tcpv4_gso_segment_csum(seg,
+					 &iph2->daddr, iph->daddr,
+					 &th2->dest, th->dest);
+	}
+
+	return segs;
+}
+
+static struct sk_buff *__tcp4_gso_segment_list(struct sk_buff *skb,
+					      netdev_features_t features)
+{
+	skb = skb_segment_list(skb, features, skb_mac_header_len(skb));
+	if (IS_ERR(skb))
+		return skb;
+
+	return __tcpv4_gso_segment_list_csum(skb);
+}
+
 static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb,
 					netdev_features_t features)
 {
@@ -37,6 +101,9 @@ static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb,
 	if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
 		return ERR_PTR(-EINVAL);
 
+	if (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST)
+		return __tcp4_gso_segment_list(skb, features);
+
 	if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
 		const struct iphdr *iph = ip_hdr(skb);
 		struct tcphdr *th = tcp_hdr(skb);
diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c
index 4b07d1e6c952..7180c30dbbef 100644
--- a/net/ipv6/tcpv6_offload.c
+++ b/net/ipv6/tcpv6_offload.c
@@ -40,6 +40,61 @@ INDIRECT_CALLABLE_SCOPE int tcp6_gro_complete(struct sk_buff *skb, int thoff)
 	return 0;
 }
 
+static void __tcpv6_gso_segment_csum(struct sk_buff *seg,
+				     __be16 *oldport, __be16 newport)
+{
+	struct tcphdr *th;
+
+	if (*oldport == newport)
+		return;
+
+	th = tcp_hdr(seg);
+	inet_proto_csum_replace2(&th->check, seg, *oldport, newport, false);
+	*oldport = newport;
+}
+
+static struct sk_buff *__tcpv6_gso_segment_list_csum(struct sk_buff *segs)
+{
+	const struct tcphdr *th;
+	const struct ipv6hdr *iph;
+	struct sk_buff *seg;
+	struct tcphdr *th2;
+	struct ipv6hdr *iph2;
+
+	seg = segs;
+	th = tcp_hdr(seg);
+	iph = ipv6_hdr(seg);
+	th2 = tcp_hdr(seg->next);
+	iph2 = ipv6_hdr(seg->next);
+
+	if (!(*(const u32 *)&th->source ^ *(const u32 *)&th2->source) &&
+	    ipv6_addr_equal(&iph->saddr, &iph2->saddr) &&
+	    ipv6_addr_equal(&iph->daddr, &iph2->daddr))
+		return segs;
+
+	while ((seg = seg->next)) {
+		th2 = tcp_hdr(seg);
+		iph2 = ipv6_hdr(seg);
+
+		iph2->saddr = iph->saddr;
+		iph2->daddr = iph->daddr;
+		__tcpv6_gso_segment_csum(seg, &th2->source, th->source);
+		__tcpv6_gso_segment_csum(seg, &th2->dest, th->dest);
+	}
+
+	return segs;
+}
+
+static struct sk_buff *__tcp6_gso_segment_list(struct sk_buff *skb,
+					      netdev_features_t features)
+{
+	skb = skb_segment_list(skb, features, skb_mac_header_len(skb));
+	if (IS_ERR(skb))
+		return skb;
+
+	return __tcpv6_gso_segment_list_csum(skb);
+}
+
 static struct sk_buff *tcp6_gso_segment(struct sk_buff *skb,
 					netdev_features_t features)
 {
@@ -51,6 +106,9 @@ static struct sk_buff *tcp6_gso_segment(struct sk_buff *skb,
 	if (!pskb_may_pull(skb, sizeof(*th)))
 		return ERR_PTR(-EINVAL);
 
+	if (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST)
+		return __tcp6_gso_segment_list(skb, features);
+
 	if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
 		const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 		struct tcphdr *th = tcp_hdr(skb);
-- 
2.44.0

Re: [PATCH v5 net-next v5 2/6] net: add support for segmenting TCP fraglist GSO packets

[David Ahern]

On 5/2/24 2:44 AM, Felix Fietkau wrote:
> Preparation for adding TCP fraglist GRO support. It expects packets to be
> combined in a similar way as UDP fraglist GSO packets.
> For IPv4 packets, NAT is handled in the same way as UDP fraglist GSO.
> 
> Acked-by: Paolo Abeni <pabeni@redhat.com>
> Reviewed-by: Eric Dumazet <edumazet@google.com>
> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> ---
>  net/ipv4/tcp_offload.c   | 67 ++++++++++++++++++++++++++++++++++++++++
>  net/ipv6/tcpv6_offload.c | 58 ++++++++++++++++++++++++++++++++++
>  2 files changed, 125 insertions(+)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>

[PATCH v5 net-next v5 3/6] net: add code for TCP fraglist GRO

[Felix Fietkau]

This implements fraglist GRO similar to how it's handled in UDP, however
no functional changes are added yet. The next change adds a heuristic for
using fraglist GRO instead of regular GRO.

Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 net/ipv4/tcp_offload.c   | 21 +++++++++++++++++++++
 net/ipv6/tcpv6_offload.c |  9 +++++++++
 2 files changed, 30 insertions(+)

diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index affd4ed28cfe..aa7508676315 100644
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -334,6 +334,18 @@ struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb)
 	flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
 	flush |= skb_cmp_decrypted(p, skb);
 
+	if (unlikely(NAPI_GRO_CB(p)->is_flist)) {
+		flush |= (__force int)(flags ^ tcp_flag_word(th2));
+		flush |= skb->ip_summed != p->ip_summed;
+		flush |= skb->csum_level != p->csum_level;
+		flush |= NAPI_GRO_CB(p)->count >= 64;
+
+		if (flush || skb_gro_receive_list(p, skb))
+			mss = 1;
+
+		goto out_check_final;
+	}
+
 	if (flush || skb_gro_receive(p, skb)) {
 		mss = 1;
 		goto out_check_final;
@@ -400,6 +412,15 @@ INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff)
 	const struct iphdr *iph = ip_hdr(skb);
 	struct tcphdr *th = tcp_hdr(skb);
 
+	if (unlikely(NAPI_GRO_CB(skb)->is_flist)) {
+		skb_shinfo(skb)->gso_type |= SKB_GSO_FRAGLIST | SKB_GSO_TCPV4;
+		skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
+
+		__skb_incr_checksum_unnecessary(skb);
+
+		return 0;
+	}
+
 	th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr,
 				  iph->daddr, 0);
 
diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c
index 7180c30dbbef..575e2743e331 100644
--- a/net/ipv6/tcpv6_offload.c
+++ b/net/ipv6/tcpv6_offload.c
@@ -32,6 +32,15 @@ INDIRECT_CALLABLE_SCOPE int tcp6_gro_complete(struct sk_buff *skb, int thoff)
 	const struct ipv6hdr *iph = ipv6_hdr(skb);
 	struct tcphdr *th = tcp_hdr(skb);
 
+	if (unlikely(NAPI_GRO_CB(skb)->is_flist)) {
+		skb_shinfo(skb)->gso_type |= SKB_GSO_FRAGLIST | SKB_GSO_TCPV6;
+		skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
+
+		__skb_incr_checksum_unnecessary(skb);
+
+		return 0;
+	}
+
 	th->check = ~tcp_v6_check(skb->len - thoff, &iph->saddr,
 				  &iph->daddr, 0);
 	skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV6;
-- 
2.44.0

Re: [PATCH v5 net-next v5 3/6] net: add code for TCP fraglist GRO

[Eric Dumazet]

On Thu, May 2, 2024 at 10:44 AM Felix Fietkau <nbd@nbd.name> wrote:
>
> This implements fraglist GRO similar to how it's handled in UDP, however
> no functional changes are added yet. The next change adds a heuristic for
> using fraglist GRO instead of regular GRO.
>
> Acked-by: Paolo Abeni <pabeni@redhat.com>
> Signed-off-by: Felix Fietkau <nbd@nbd.name>

Reviewed-by: Eric Dumazet <edumazet@google.com>

Re: [PATCH v5 net-next v5 3/6] net: add code for TCP fraglist GRO

[David Ahern]

On 5/2/24 2:44 AM, Felix Fietkau wrote:
> This implements fraglist GRO similar to how it's handled in UDP, however
> no functional changes are added yet. The next change adds a heuristic for
> using fraglist GRO instead of regular GRO.
> 
> Acked-by: Paolo Abeni <pabeni@redhat.com>
> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> ---
>  net/ipv4/tcp_offload.c   | 21 +++++++++++++++++++++
>  net/ipv6/tcpv6_offload.c |  9 +++++++++
>  2 files changed, 30 insertions(+)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>

[PATCH v5 net-next v5 4/6] net: create tcp_gro_lookup helper function

[Felix Fietkau]

This pulls the flow port matching out of tcp_gro_receive, so that it can be
reused for the next change, which adds the TCP fraglist GRO heuristic.

Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 include/net/tcp.h      |  1 +
 net/ipv4/tcp_offload.c | 41 +++++++++++++++++++++++++----------------
 2 files changed, 26 insertions(+), 16 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index a9eb21251195..9f08ecab26e0 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2199,6 +2199,7 @@ void tcp_v4_destroy_sock(struct sock *sk);
 
 struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
 				netdev_features_t features);
+struct sk_buff *tcp_gro_lookup(struct list_head *head, struct tcphdr *th);
 struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb);
 INDIRECT_CALLABLE_DECLARE(int tcp4_gro_complete(struct sk_buff *skb, int thoff));
 INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb));
diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index aa7508676315..4a194a9d36cd 100644
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -245,6 +245,27 @@ struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
 	return segs;
 }
 
+struct sk_buff *tcp_gro_lookup(struct list_head *head, struct tcphdr *th)
+{
+	struct tcphdr *th2;
+	struct sk_buff *p;
+
+	list_for_each_entry(p, head, list) {
+		if (!NAPI_GRO_CB(p)->same_flow)
+			continue;
+
+		th2 = tcp_hdr(p);
+		if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
+			NAPI_GRO_CB(p)->same_flow = 0;
+			continue;
+		}
+
+		return p;
+	}
+
+	return NULL;
+}
+
 struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb)
 {
 	struct sk_buff *pp = NULL;
@@ -282,24 +303,12 @@ struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb)
 	len = skb_gro_len(skb);
 	flags = tcp_flag_word(th);
 
-	list_for_each_entry(p, head, list) {
-		if (!NAPI_GRO_CB(p)->same_flow)
-			continue;
-
-		th2 = tcp_hdr(p);
-
-		if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
-			NAPI_GRO_CB(p)->same_flow = 0;
-			continue;
-		}
-
-		goto found;
-	}
-	p = NULL;
-	goto out_check_final;
+	p = tcp_gro_lookup(head, th);
+	if (!p)
+		goto out_check_final;
 
-found:
 	/* Include the IP ID check below from the inner most IP hdr */
+	th2 = tcp_hdr(p);
 	flush = NAPI_GRO_CB(p)->flush;
 	flush |= (__force int)(flags & TCP_FLAG_CWR);
 	flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
-- 
2.44.0

Re: [PATCH v5 net-next v5 4/6] net: create tcp_gro_lookup helper function

[David Ahern]

On 5/2/24 2:44 AM, Felix Fietkau wrote:
> This pulls the flow port matching out of tcp_gro_receive, so that it can be
> reused for the next change, which adds the TCP fraglist GRO heuristic.
> 
> Acked-by: Paolo Abeni <pabeni@redhat.com>
> Reviewed-by: Eric Dumazet <edumazet@google.com>
> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> ---
>  include/net/tcp.h      |  1 +
>  net/ipv4/tcp_offload.c | 41 +++++++++++++++++++++++++----------------
>  2 files changed, 26 insertions(+), 16 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>

[PATCH v5 net-next v5 5/6] net: create tcp_gro_header_pull helper function

[Felix Fietkau]

Pull the code out of tcp_gro_receive in order to access the tcp header
from tcp4/6_gro_receive.

Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 include/net/tcp.h        |  4 ++-
 net/ipv4/tcp_offload.c   | 55 +++++++++++++++++++++++++---------------
 net/ipv6/tcpv6_offload.c | 18 +++++++++----
 3 files changed, 50 insertions(+), 27 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 9f08ecab26e0..bf392c1fbadc 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2199,8 +2199,10 @@ void tcp_v4_destroy_sock(struct sock *sk);
 
 struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
 				netdev_features_t features);
+struct tcphdr *tcp_gro_pull_header(struct sk_buff *skb);
 struct sk_buff *tcp_gro_lookup(struct list_head *head, struct tcphdr *th);
-struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb);
+struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb,
+				struct tcphdr *th);
 INDIRECT_CALLABLE_DECLARE(int tcp4_gro_complete(struct sk_buff *skb, int thoff));
 INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb));
 INDIRECT_CALLABLE_DECLARE(int tcp6_gro_complete(struct sk_buff *skb, int thoff));
diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index 4a194a9d36cd..87ae9808e260 100644
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -266,40 +266,46 @@ struct sk_buff *tcp_gro_lookup(struct list_head *head, struct tcphdr *th)
 	return NULL;
 }
 
-struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb)
+struct tcphdr *tcp_gro_pull_header(struct sk_buff *skb)
 {
-	struct sk_buff *pp = NULL;
-	struct sk_buff *p;
+	unsigned int thlen, hlen, off;
 	struct tcphdr *th;
-	struct tcphdr *th2;
-	unsigned int len;
-	unsigned int thlen;
-	__be32 flags;
-	unsigned int mss = 1;
-	unsigned int hlen;
-	unsigned int off;
-	int flush = 1;
-	int i;
 
 	off = skb_gro_offset(skb);
 	hlen = off + sizeof(*th);
 	th = skb_gro_header(skb, hlen, off);
 	if (unlikely(!th))
-		goto out;
+		return NULL;
 
 	thlen = th->doff * 4;
 	if (thlen < sizeof(*th))
-		goto out;
+		return NULL;
 
 	hlen = off + thlen;
 	if (!skb_gro_may_pull(skb, hlen)) {
 		th = skb_gro_header_slow(skb, hlen, off);
 		if (unlikely(!th))
-			goto out;
+			return NULL;
 	}
 
 	skb_gro_pull(skb, thlen);
 
+	return th;
+}
+
+struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb,
+				struct tcphdr *th)
+{
+	unsigned int thlen = th->doff * 4;
+	struct sk_buff *pp = NULL;
+	struct sk_buff *p;
+	struct tcphdr *th2;
+	unsigned int len;
+	__be32 flags;
+	unsigned int mss = 1;
+	int flush = 1;
+	int i;
+
 	len = skb_gro_len(skb);
 	flags = tcp_flag_word(th);
 
@@ -376,7 +382,6 @@ struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb)
 	if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
 		pp = p;
 
-out:
 	NAPI_GRO_CB(skb)->flush |= (flush != 0);
 
 	return pp;
@@ -405,15 +410,23 @@ EXPORT_SYMBOL(tcp_gro_complete);
 INDIRECT_CALLABLE_SCOPE
 struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb)
 {
+	struct tcphdr *th;
+
 	/* Don't bother verifying checksum if we're going to flush anyway. */
 	if (!NAPI_GRO_CB(skb)->flush &&
 	    skb_gro_checksum_validate(skb, IPPROTO_TCP,
-				      inet_gro_compute_pseudo)) {
-		NAPI_GRO_CB(skb)->flush = 1;
-		return NULL;
-	}
+				      inet_gro_compute_pseudo))
+		goto flush;
+
+	th = tcp_gro_pull_header(skb);
+	if (!th)
+		goto flush;
 
-	return tcp_gro_receive(head, skb);
+	return tcp_gro_receive(head, skb, th);
+
+flush:
+	NAPI_GRO_CB(skb)->flush = 1;
+	return NULL;
 }
 
 INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff)
diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c
index 575e2743e331..e73a4f74fd96 100644
--- a/net/ipv6/tcpv6_offload.c
+++ b/net/ipv6/tcpv6_offload.c
@@ -16,15 +16,23 @@
 INDIRECT_CALLABLE_SCOPE
 struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb)
 {
+	struct tcphdr *th;
+
 	/* Don't bother verifying checksum if we're going to flush anyway. */
 	if (!NAPI_GRO_CB(skb)->flush &&
 	    skb_gro_checksum_validate(skb, IPPROTO_TCP,
-				      ip6_gro_compute_pseudo)) {
-		NAPI_GRO_CB(skb)->flush = 1;
-		return NULL;
-	}
+				      ip6_gro_compute_pseudo))
+		goto flush;
+
+	th = tcp_gro_pull_header(skb);
+	if (!th)
+		goto flush;
+
+	return tcp_gro_receive(head, skb, th);
 
-	return tcp_gro_receive(head, skb);
+flush:
+	NAPI_GRO_CB(skb)->flush = 1;
+	return NULL;
 }
 
 INDIRECT_CALLABLE_SCOPE int tcp6_gro_complete(struct sk_buff *skb, int thoff)
-- 
2.44.0

Re: [PATCH v5 net-next v5 5/6] net: create tcp_gro_header_pull helper function

[David Ahern]

On 5/2/24 2:44 AM, Felix Fietkau wrote:
> Pull the code out of tcp_gro_receive in order to access the tcp header
> from tcp4/6_gro_receive.
> 
> Acked-by: Paolo Abeni <pabeni@redhat.com>
> Reviewed-by: Eric Dumazet <edumazet@google.com>
> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> ---
>  include/net/tcp.h        |  4 ++-
>  net/ipv4/tcp_offload.c   | 55 +++++++++++++++++++++++++---------------
>  net/ipv6/tcpv6_offload.c | 18 +++++++++----
>  3 files changed, 50 insertions(+), 27 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>

[PATCH v5 net-next v5 6/6] net: add heuristic for enabling TCP fraglist GRO

[Felix Fietkau]

When forwarding TCP after GRO, software segmentation is very expensive,
especially when the checksum needs to be recalculated.
One case where that's currently unavoidable is when routing packets over
PPPoE. Performance improves significantly when using fraglist GRO
implemented in the same way as for UDP.

When NETIF_F_GRO_FRAGLIST is enabled, perform a lookup for an established
socket in the same netns as the receiving device. While this may not
cover all relevant use cases in multi-netns configurations, it should be
good enough for most configurations that need this.

Here's a measurement of running 2 TCP streams through a MediaTek MT7622
device (2-core Cortex-A53), which runs NAT with flow offload enabled from
one ethernet port to PPPoE on another ethernet port + cake qdisc set to
1Gbps.

rx-gro-list off: 630 Mbit/s, CPU 35% idle
rx-gro-list on:  770 Mbit/s, CPU 40% idle

Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 net/ipv4/tcp_offload.c   | 32 ++++++++++++++++++++++++++++++++
 net/ipv6/tcpv6_offload.c | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+)

diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index 87ae9808e260..c90704befd7b 100644
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -407,6 +407,36 @@ void tcp_gro_complete(struct sk_buff *skb)
 }
 EXPORT_SYMBOL(tcp_gro_complete);
 
+static void tcp4_check_fraglist_gro(struct list_head *head, struct sk_buff *skb,
+				    struct tcphdr *th)
+{
+	const struct iphdr *iph;
+	struct sk_buff *p;
+	struct sock *sk;
+	struct net *net;
+	int iif, sdif;
+
+	if (likely(!(skb->dev->features & NETIF_F_GRO_FRAGLIST)))
+		return;
+
+	p = tcp_gro_lookup(head, th);
+	if (p) {
+		NAPI_GRO_CB(skb)->is_flist = NAPI_GRO_CB(p)->is_flist;
+		return;
+	}
+
+	inet_get_iif_sdif(skb, &iif, &sdif);
+	iph = skb_gro_network_header(skb);
+	net = dev_net(skb->dev);
+	sk = __inet_lookup_established(net, net->ipv4.tcp_death_row.hashinfo,
+				       iph->saddr, th->source,
+				       iph->daddr, ntohs(th->dest),
+				       iif, sdif);
+	NAPI_GRO_CB(skb)->is_flist = !sk;
+	if (sk)
+		sock_put(sk);
+}
+
 INDIRECT_CALLABLE_SCOPE
 struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb)
 {
@@ -422,6 +452,8 @@ struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb)
 	if (!th)
 		goto flush;
 
+	tcp4_check_fraglist_gro(head, skb, th);
+
 	return tcp_gro_receive(head, skb, th);
 
 flush:
diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c
index e73a4f74fd96..d59f58cbd306 100644
--- a/net/ipv6/tcpv6_offload.c
+++ b/net/ipv6/tcpv6_offload.c
@@ -7,12 +7,45 @@
  */
 #include <linux/indirect_call_wrapper.h>
 #include <linux/skbuff.h>
+#include <net/inet6_hashtables.h>
 #include <net/gro.h>
 #include <net/protocol.h>
 #include <net/tcp.h>
 #include <net/ip6_checksum.h>
 #include "ip6_offload.h"
 
+static void tcp6_check_fraglist_gro(struct list_head *head, struct sk_buff *skb,
+				    struct tcphdr *th)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	const struct ipv6hdr *hdr;
+	struct sk_buff *p;
+	struct sock *sk;
+	struct net *net;
+	int iif, sdif;
+
+	if (likely(!(skb->dev->features & NETIF_F_GRO_FRAGLIST)))
+		return;
+
+	p = tcp_gro_lookup(head, th);
+	if (p) {
+		NAPI_GRO_CB(skb)->is_flist = NAPI_GRO_CB(p)->is_flist;
+		return;
+	}
+
+	inet6_get_iif_sdif(skb, &iif, &sdif);
+	hdr = skb_gro_network_header(skb);
+	net = dev_net(skb->dev);
+	sk = __inet6_lookup_established(net, net->ipv4.tcp_death_row.hashinfo,
+					&hdr->saddr, th->source,
+					&hdr->daddr, ntohs(th->dest),
+					iif, sdif);
+	NAPI_GRO_CB(skb)->is_flist = !sk;
+	if (sk)
+		sock_put(sk);
+#endif /* IS_ENABLED(CONFIG_IPV6) */
+}
+
 INDIRECT_CALLABLE_SCOPE
 struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb)
 {
@@ -28,6 +61,8 @@ struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb)
 	if (!th)
 		goto flush;
 
+	tcp6_check_fraglist_gro(head, skb, th);
+
 	return tcp_gro_receive(head, skb, th);
 
 flush:
-- 
2.44.0

Re: [PATCH v5 net-next v5 6/6] net: add heuristic for enabling TCP fraglist GRO

[David Ahern]

On 5/2/24 2:44 AM, Felix Fietkau wrote:
> When forwarding TCP after GRO, software segmentation is very expensive,
> especially when the checksum needs to be recalculated.
> One case where that's currently unavoidable is when routing packets over
> PPPoE. Performance improves significantly when using fraglist GRO
> implemented in the same way as for UDP.
> 
> When NETIF_F_GRO_FRAGLIST is enabled, perform a lookup for an established
> socket in the same netns as the receiving device. While this may not
> cover all relevant use cases in multi-netns configurations, it should be
> good enough for most configurations that need this.
> 
> Here's a measurement of running 2 TCP streams through a MediaTek MT7622
> device (2-core Cortex-A53), which runs NAT with flow offload enabled from
> one ethernet port to PPPoE on another ethernet port + cake qdisc set to
> 1Gbps.
> 
> rx-gro-list off: 630 Mbit/s, CPU 35% idle
> rx-gro-list on:  770 Mbit/s, CPU 40% idle
> 
> Acked-by: Paolo Abeni <pabeni@redhat.com>
> Reviewed-by: Eric Dumazet <edumazet@google.com>
> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> ---
>  net/ipv4/tcp_offload.c   | 32 ++++++++++++++++++++++++++++++++
>  net/ipv6/tcpv6_offload.c | 35 +++++++++++++++++++++++++++++++++++
>  2 files changed, 67 insertions(+)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>