[PATCH] gro: fix the chain index in insert_new_item for more than 2 packets

[PATCH] gro: fix the chain index in insert_new_item for more than 2 packets

[Kumara Parameshwaran]

From: Kumara Parameshwaran <kumaraparamesh92@gmail.com>

When more than two packets are merged in a flow, and if we receive
a 3rd packet which is matching the sequence of the 2nd packet the
prev_idx will be 1 and not 2, hence resulting in packet re-ordering

Signed-off-by: Kumara Parameshwaran <kumaraparamesh92@gmail.com>
---
V1:
	Initial changes to fix packet reordering issue when 
	more than 2 items are chained in a flow.
	Ex:
		3 mergeable TCP packets received in order.
		packet_0 - no flow found so insert the packet and new start
		index -> 0
		packet_1-> flow found. prev_idx, curr_index = 0. So merge works
		find packet_0->packet_1
		packet_3 flow found. prev_indx =0, curr_index = 1. Matching
		dequence numbers found but chained as
		packet_0->packet_2->packet_1

 lib/gro/gro_tcp4.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/gro/gro_tcp4.c b/lib/gro/gro_tcp4.c
index 7498c66141..9758e28fd5 100644
--- a/lib/gro/gro_tcp4.c
+++ b/lib/gro/gro_tcp4.c
@@ -305,7 +305,7 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt,
 			 * length is greater than the max value. Store
 			 * the packet into the flow.
 			 */
-			if (insert_new_item(tbl, pkt, start_time, prev_idx,
+			if (insert_new_item(tbl, pkt, start_time, cur_idx,
 						sent_seq, ip_id, is_atomic) ==
 					INVALID_ARRAY_INDEX)
 				return -1;
-- 
2.25.1

[PATCH] gro: fix the chain index in insert_new_item for more than 2 packets

[Kumara Parameshwaran]

From: Kumara Parameshwaran <kumaraparamesh92@gmail.com>

When more than two packets are merged in a flow, and if we receive
a 3rd packet which is matching the sequence of the 2nd packet the
prev_idx will be 1 and not 2, hence resulting in packet re-ordering

Signed-off-by: Kumara Parameshwaran <kumaraparamesh92@gmail.com>
---
V1:
	Initial changes to fix packet reordering issue when 
	more than 2 items are chained in a flow.
	Ex:
		3 mergeable TCP packets received in order.
		packet_0 - no flow found so insert the packet and new start
		index -> 0
		packet_1-> flow found. prev_idx, curr_index = 0. So merge works
		find packet_0->packet_1
		packet_2 flow found. prev_indx =0, curr_index = 1. Matching
		dequence numbers found but chained as
		packet_0->packet_2->packet_1

 lib/gro/gro_tcp4.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/gro/gro_tcp4.c b/lib/gro/gro_tcp4.c
index 7498c66141..9758e28fd5 100644
--- a/lib/gro/gro_tcp4.c
+++ b/lib/gro/gro_tcp4.c
@@ -305,7 +305,7 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt,
 			 * length is greater than the max value. Store
 			 * the packet into the flow.
 			 */
-			if (insert_new_item(tbl, pkt, start_time, prev_idx,
+			if (insert_new_item(tbl, pkt, start_time, cur_idx,
 						sent_seq, ip_id, is_atomic) ==
 					INVALID_ARRAY_INDEX)
 				return -1;
-- 
2.25.1

RE: [PATCH] gro: fix the chain index in insert_new_item for more than 2 packets

[Hu, Jiayu]

> -----Original Message-----
> From: Kumara Parameshwaran <kumaraparamesh92@gmail.com>
> Sent: Wednesday, September 7, 2022 5:32 PM
> To: Hu, Jiayu <jiayu.hu@intel.com>
> Cc: dev@dpdk.org; Kumara Parameshwaran
> <kumaraparamesh92@gmail.com>
> Subject: [PATCH] gro: fix the chain index in insert_new_item for more than 2
> packets
> 
> From: Kumara Parameshwaran <kumaraparamesh92@gmail.com>
> 
> When more than two packets are merged in a flow, and if we receive a 3rd
> packet which is matching the sequence of the 2nd packet the prev_idx will
> be 1 and not 2, hence resulting in packet re-ordering
> 
> Signed-off-by: Kumara Parameshwaran <kumaraparamesh92@gmail.com>
> ---
> V1:
> 	Initial changes to fix packet reordering issue when
> 	more than 2 items are chained in a flow.
> 	Ex:
> 		3 mergeable TCP packets received in order.
> 		packet_0 - no flow found so insert the packet and new start
> 		index -> 0
> 		packet_1-> flow found. prev_idx, curr_index = 0. So merge
> works
> 		find packet_0->packet_1
> 		packet_2 flow found. prev_indx =0, curr_index = 1. Matching
> 		dequence numbers found but chained as
> 		packet_0->packet_2->packet_1
> 
>  lib/gro/gro_tcp4.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/gro/gro_tcp4.c b/lib/gro/gro_tcp4.c index
> 7498c66141..9758e28fd5 100644
> --- a/lib/gro/gro_tcp4.c
> +++ b/lib/gro/gro_tcp4.c
> @@ -305,7 +305,7 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt,
>  			 * length is greater than the max value. Store
>  			 * the packet into the flow.
>  			 */
> -			if (insert_new_item(tbl, pkt, start_time, prev_idx,
> +			if (insert_new_item(tbl, pkt, start_time, cur_idx,
>  						sent_seq, ip_id, is_atomic)

Good catch.

Acked-by: Jiayu Hu <Jiayu.hu@intel.com>

Thanks,
Jiayu
> ==
>  					INVALID_ARRAY_INDEX)
>  				return -1;
> --
> 2.25.1

Re: [PATCH] gro: fix the chain index in insert_new_item for more than 2 packets

[Thomas Monjalon]

> > When more than two packets are merged in a flow, and if we receive a 3rd
> > packet which is matching the sequence of the 2nd packet the prev_idx will
> > be 1 and not 2, hence resulting in packet re-ordering
> > 
> > Signed-off-by: Kumara Parameshwaran <kumaraparamesh92@gmail.com>
> > ---
> > V1:
> > 	Initial changes to fix packet reordering issue when
> > 	more than 2 items are chained in a flow.
> > 	Ex:
> > 		3 mergeable TCP packets received in order.
> > 		packet_0 - no flow found so insert the packet and new start
> > 		index -> 0
> > 		packet_1-> flow found. prev_idx, curr_index = 0. So merge
> > works
> > 		find packet_0->packet_1
> > 		packet_2 flow found. prev_indx =0, curr_index = 1. Matching
> > 		dequence numbers found but chained as
> > 		packet_0->packet_2->packet_1
> > 
> >  lib/gro/gro_tcp4.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/lib/gro/gro_tcp4.c b/lib/gro/gro_tcp4.c index
> > 7498c66141..9758e28fd5 100644
> > --- a/lib/gro/gro_tcp4.c
> > +++ b/lib/gro/gro_tcp4.c
> > @@ -305,7 +305,7 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt,
> >  			 * length is greater than the max value. Store
> >  			 * the packet into the flow.
> >  			 */
> > -			if (insert_new_item(tbl, pkt, start_time, prev_idx,
> > +			if (insert_new_item(tbl, pkt, start_time, cur_idx,
> >  						sent_seq, ip_id, is_atomic)
> 
> Good catch.
> 
> Acked-by: Jiayu Hu <Jiayu.hu@intel.com>

Applied, thanks.

[PATCH v5] gro : fix reordering of packets in GRO library

[Kumara Parameshwaran]

From: Kumara Parameshwaran <kumaraparamesh92@gmail.com>

When a TCP packet contains flags like PSH it is returned
immediately to the application though there might be packets of
the same flow in the GRO table. If PSH flag is set on a segment
packets up to the segment should be delivered immediately. But the
current implementation delivers the last arrived packet with PSH flag
set causing re-ordering

With this patch, if a packet does not contain only ACK flag and if
there are no previous packets for the flow the packet would be returned
immediately, else will be merged with the previous segment and the
flag on the last segment will be set on the entire segment.
This is the behaviour with linux stack as well.

Signed-off-by: Kumara Parameshwaran <kumaraparamesh92@gmail.com>
Co-authored-by: Kumara Parameshwaran <kparameshwar@vmware.com>
---
v1:
	If the received packet is not a pure ACK packet, we check if
	there are any previous packets in the flow, if present we indulge
	the received packet also in the coalescing logic and update the flags
	of the last recived packet to the entire segment which would avoid
	re-ordering.

	Lets say a case where P1(PSH), P2(ACK), P3(ACK)  are received in burst mode,
	P1 contains PSH flag and since it does not contain any prior packets in the flow
	we copy it to unprocess_packets and P2(ACK) and P3(ACK) are merged together.
	In the existing case the  P2,P3 would be delivered as single segment first and the
	unprocess_packets will be copied later which will cause reordering. With the patch
	copy the unprocess packets first and then the packets from the GRO table.

	Testing done
	The csum test-pmd was modifited to support the following
	GET request of 10MB from client to server via test-pmd (static arp entries added in client
	and server). Enable GRO and TSO in test-pmd where the packets recived from the client mac
	would be sent to server mac and vice versa.
	In above testing, without the patch the client observerd re-ordering of 25 packets
	and with the patch there were no packet re-ordering observerd.

v2: 
	Fix warnings in commit and comment.
	Do not consider packet as candidate to merge if it contains SYN/RST flag.

v3:
	Fix warnings.

v4:
	Rebase with master.

v5:
	Adding co-author email

 lib/gro/gro_tcp4.c | 45 +++++++++++++++++++++++++++++++++++++--------
 lib/gro/rte_gro.c  | 18 +++++++++---------
 2 files changed, 46 insertions(+), 17 deletions(-)

diff --git a/lib/gro/gro_tcp4.c b/lib/gro/gro_tcp4.c
index 0014096e63..7363c5d540 100644
--- a/lib/gro/gro_tcp4.c
+++ b/lib/gro/gro_tcp4.c
@@ -188,6 +188,19 @@ update_header(struct gro_tcp4_item *item)
 			pkt->l2_len);
 }
 
+static inline void
+update_tcp_hdr_flags(struct rte_tcp_hdr *tcp_hdr, struct rte_mbuf *pkt)
+{
+	struct rte_ether_hdr *eth_hdr;
+	struct rte_ipv4_hdr *ipv4_hdr;
+	struct rte_tcp_hdr *merged_tcp_hdr;
+
+	eth_hdr = rte_pktmbuf_mtod(pkt, struct rte_ether_hdr *);
+	ipv4_hdr = (struct rte_ipv4_hdr *)((char *)eth_hdr + pkt->l2_len);
+	merged_tcp_hdr = (struct rte_tcp_hdr *)((char *)ipv4_hdr + pkt->l3_len);
+	merged_tcp_hdr->tcp_flags |= tcp_hdr->tcp_flags;
+}
+
 int32_t
 gro_tcp4_reassemble(struct rte_mbuf *pkt,
 		struct gro_tcp4_tbl *tbl,
@@ -206,6 +219,7 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt,
 	uint32_t i, max_flow_num, remaining_flow_num;
 	int cmp;
 	uint8_t find;
+	uint32_t start_idx;
 
 	/*
 	 * Don't process the packet whose TCP header length is greater
@@ -219,13 +233,6 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt,
 	tcp_hdr = (struct rte_tcp_hdr *)((char *)ipv4_hdr + pkt->l3_len);
 	hdr_len = pkt->l2_len + pkt->l3_len + pkt->l4_len;
 
-	/*
-	 * Don't process the packet which has FIN, SYN, RST, PSH, URG, ECE
-	 * or CWR set.
-	 */
-	if (tcp_hdr->tcp_flags != RTE_TCP_ACK_FLAG)
-		return -1;
-
 	/* trim the tail padding bytes */
 	ip_tlen = rte_be_to_cpu_16(ipv4_hdr->total_length);
 	if (pkt->pkt_len > (uint32_t)(ip_tlen + pkt->l2_len))
@@ -264,12 +271,30 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt,
 		if (tbl->flows[i].start_index != INVALID_ARRAY_INDEX) {
 			if (is_same_tcp4_flow(tbl->flows[i].key, key)) {
 				find = 1;
+				start_idx = tbl->flows[i].start_index;
 				break;
 			}
 			remaining_flow_num--;
 		}
 	}
 
+	if (tcp_hdr->tcp_flags != RTE_TCP_ACK_FLAG) {
+		/*
+		 * Check and try merging the current TCP segment with the previous
+		 * TCP segment if the TCP header does not contain RST and SYN flag
+		 * There are cases where the last segment is sent with FIN|PSH|ACK
+		 * which should also be considered for merging with previous segments.
+		 */
+		if (find && !(tcp_hdr->tcp_flags & (RTE_TCP_RST_FLAG|RTE_TCP_SYN_FLAG)))
+			/*
+			 * Since PSH flag is set, start time will be set to 0 so it will be flushed
+			 * immediately.
+			 */
+			tbl->items[start_idx].start_time = 0;
+		else
+			return -1;
+	}
+
 	/*
 	 * Fail to find a matched flow. Insert a new flow and store the
 	 * packet into the flow.
@@ -304,8 +329,12 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt,
 				is_atomic);
 		if (cmp) {
 			if (merge_two_tcp4_packets(&(tbl->items[cur_idx]),
-						pkt, cmp, sent_seq, ip_id, 0))
+						pkt, cmp, sent_seq, ip_id, 0)) {
+				if (tbl->items[cur_idx].start_time == 0)
+					update_tcp_hdr_flags(tcp_hdr, tbl->items[cur_idx].firstseg);
 				return 1;
+			}
+
 			/*
 			 * Fail to merge the two packets, as the packet
 			 * length is greater than the max value. Store
diff --git a/lib/gro/rte_gro.c b/lib/gro/rte_gro.c
index e35399fd42..87c5502dce 100644
--- a/lib/gro/rte_gro.c
+++ b/lib/gro/rte_gro.c
@@ -283,10 +283,17 @@ rte_gro_reassemble_burst(struct rte_mbuf **pkts,
 	if ((nb_after_gro < nb_pkts)
 		 || (unprocess_num < nb_pkts)) {
 		i = 0;
+		/* Copy unprocessed packets */
+		if (unprocess_num > 0) {
+			memcpy(&pkts[i], unprocess_pkts,
+					sizeof(struct rte_mbuf *) *
+					unprocess_num);
+			i = unprocess_num;
+		}
 		/* Flush all packets from the tables */
 		if (do_vxlan_tcp_gro) {
-			i = gro_vxlan_tcp4_tbl_timeout_flush(&vxlan_tcp_tbl,
-					0, pkts, nb_pkts);
+			i += gro_vxlan_tcp4_tbl_timeout_flush(&vxlan_tcp_tbl,
+					0, &pkts[i], nb_pkts - i);
 		}
 
 		if (do_vxlan_udp_gro) {
@@ -304,13 +311,6 @@ rte_gro_reassemble_burst(struct rte_mbuf **pkts,
 			i += gro_udp4_tbl_timeout_flush(&udp_tbl, 0,
 					&pkts[i], nb_pkts - i);
 		}
-		/* Copy unprocessed packets */
-		if (unprocess_num > 0) {
-			memcpy(&pkts[i], unprocess_pkts,
-					sizeof(struct rte_mbuf *) *
-					unprocess_num);
-		}
-		nb_after_gro = i + unprocess_num;
 	}
 
 	return nb_after_gro;
-- 
2.25.1