Commit a31ad29e authored by Lawrence Brakmo's avatar Lawrence Brakmo Committed by Alexei Starovoitov
Browse files

bpf: Add BPF_SOCK_OPS_RETRANS_CB 



Adds support for calling sock_ops BPF program when there is a
retransmission. Three arguments are used; one for the sequence number,
another for the number of segments retransmitted, and the last one for
the return value of tcp_transmit_skb (0 => success).
Does not include syn-ack retransmissions.

New op: BPF_SOCK_OPS_RETRANS_CB.

Signed-off-by: default avatarLawrence Brakmo <brakmo@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 6f9bd3d7

include/uapi/linux/bpf.h

+8 −1
Original line number Diff line number Diff line
@@ -1005,7 +1005,8 @@ struct bpf_sock_ops { 


/* Definitions for bpf_sock_ops_cb_flags */

#define BPF_SOCK_OPS_RTO_CB_FLAG	(1<<0)

#define BPF_SOCK_OPS_ALL_CB_FLAGS       0x1		/* Mask of all currently

#define BPF_SOCK_OPS_RETRANS_CB_FLAG	(1<<1)

#define BPF_SOCK_OPS_ALL_CB_FLAGS       0x3		/* Mask of all currently

							 * supported cb flags

							 */
@@ -1047,6 +1048,12 @@ enum { 
					 * Arg2: value of icsk_rto

					 * Arg3: whether RTO has expired

					 */

	BPF_SOCK_OPS_RETRANS_CB,	/* Called when skb is retransmitted.

					 * Arg1: sequence number of 1st byte

					 * Arg2: # segments

					 * Arg3: return value of

					 *       tcp_transmit_skb (0 => success)

					 */

};



#define TCP_BPF_IW		1001	/* Set TCP initial congestion window */

net/ipv4/tcp_output.c

+4 −0
Original line number Diff line number Diff line
@@ -2905,6 +2905,10 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) 
		err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC);

	}



	if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RETRANS_CB_FLAG))

		tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RETRANS_CB,

				  TCP_SKB_CB(skb)->seq, segs, err);



	if (likely(!err)) {

		TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS;

		trace_tcp_retransmit_skb(sk, skb);

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