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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: Lawrence Brakmo <brakmo@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Lawrence Brakmo 2018-01-25 16:14:14 -08:00 committed by Alexei Starovoitov
parent 6f9bd3d731
commit a31ad29e6a
2 changed files with 12 additions and 1 deletions
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9
include/uapi/linux/bpf.h
View File

@ -1005,7 +1005,8 @@ struct bpf_sock_ops {
/* Definitions for bpf_sock_ops_cb_flags */ /* Definitions for bpf_sock_ops_cb_flags */
#define BPF_SOCK_OPS_RTO_CB_FLAG (1<<0) #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 * supported cb flags
*/ */
@ -1047,6 +1048,12 @@ enum {
* Arg2: value of icsk_rto * Arg2: value of icsk_rto
* Arg3: whether RTO has expired * 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 */ #define TCP_BPF_IW 1001 /* Set TCP initial congestion window */

4
net/ipv4/tcp_output.c
View File

@ -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); 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)) { if (likely(!err)) {
TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS;
trace_tcp_retransmit_skb(sk, skb); trace_tcp_retransmit_skb(sk, skb);