Commit b3b81e6b authored by Jason Xing's avatar Jason Xing Committed by Martin KaFai Lau
Browse files

bpf: Add BPF_SOCK_OPS_TSTAMP_ACK_CB callback 



Support the ACK case for bpf timestamping.

Add a new sock_ops callback, BPF_SOCK_OPS_TSTAMP_ACK_CB. This
callback will occur at the same timestamping point as the user
space's SCM_TSTAMP_ACK. The BPF program can use it to get the
same SCM_TSTAMP_ACK timestamp without modifying the user-space
application.

This patch extends txstamp_ack to two bits: 1 stands for
SO_TIMESTAMPING mode, 2 bpf extension.

Signed-off-by: default avatarJason Xing <kerneljasonxing@gmail.com>
Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: default avatarWillem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250220072940.99994-10-kerneljasonxing@gmail.com
parent 2deaf7f4

include/net/tcp.h

+4 −2
Original line number Diff line number Diff line
@@ -964,10 +964,12 @@ struct tcp_skb_cb { 


	__u8		sacked;		/* State flags for SACK.	*/

	__u8		ip_dsfield;	/* IPv4 tos or IPv6 dsfield	*/

	__u8		txstamp_ack:1,	/* Record TX timestamp for ack? */

#define TSTAMP_ACK_SK	0x1

#define TSTAMP_ACK_BPF	0x2

	__u8		txstamp_ack:2,	/* Record TX timestamp for ack? */

			eor:1,		/* Is skb MSG_EOR marked? */

			has_rxtstamp:1,	/* SKB has a RX timestamp	*/

			unused:5;

			unused:4;

	__u32		ack_seq;	/* Sequence number ACK'd	*/

	union {

		struct {

include/uapi/linux/bpf.h

+5 −0
Original line number Diff line number Diff line
@@ -7044,6 +7044,11 @@ enum { 
					 * SK_BPF_CB_TX_TIMESTAMPING feature

					 * is on.

					 */

	BPF_SOCK_OPS_TSTAMP_ACK_CB,	/* Called when all the skbs in the

					 * same sendmsg call are acked

					 * when SK_BPF_CB_TX_TIMESTAMPING

					 * feature is on.

					 */

};



/* List of TCP states. There is a build check in net/ipv4/tcp.c to detect

net/core/skbuff.c

+4 −1
Original line number Diff line number Diff line
@@ -5550,7 +5550,7 @@ static bool skb_tstamp_tx_report_so_timestamping(struct sk_buff *skb, 
		return skb_shinfo(skb)->tx_flags & (hwtstamps ? SKBTX_HW_TSTAMP_NOBPF :

						    SKBTX_SW_TSTAMP);

	case SCM_TSTAMP_ACK:

		return TCP_SKB_CB(skb)->txstamp_ack;

		return TCP_SKB_CB(skb)->txstamp_ack & TSTAMP_ACK_SK;

	}



	return false;
@@ -5575,6 +5575,9 @@ static void skb_tstamp_tx_report_bpf_timestamping(struct sk_buff *skb, 
			op = BPF_SOCK_OPS_TSTAMP_SND_SW_CB;

		}

		break;

	case SCM_TSTAMP_ACK:

		op = BPF_SOCK_OPS_TSTAMP_ACK_CB;

		break;

	default:

		return;

	}

net/ipv4/tcp.c

+1 −1
Original line number Diff line number Diff line
@@ -492,7 +492,7 @@ static void tcp_tx_timestamp(struct sock *sk, struct sockcm_cookie *sockc) 


		sock_tx_timestamp(sk, sockc, &shinfo->tx_flags);

		if (tsflags & SOF_TIMESTAMPING_TX_ACK)

			tcb->txstamp_ack = 1;

			tcb->txstamp_ack |= TSTAMP_ACK_SK;

		if (tsflags & SOF_TIMESTAMPING_TX_RECORD_MASK)

			shinfo->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;

	}

tools/include/uapi/linux/bpf.h

+5 −0
Original line number Diff line number Diff line
@@ -7044,6 +7044,11 @@ enum { 
					 * SK_BPF_CB_TX_TIMESTAMPING feature

					 * is on.

					 */

	BPF_SOCK_OPS_TSTAMP_ACK_CB,	/* Called when all the skbs in the

					 * same sendmsg call are acked

					 * when SK_BPF_CB_TX_TIMESTAMPING

					 * feature is on.

					 */

};



/* List of TCP states. There is a build check in net/ipv4/tcp.c to detect