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bpf: Add BPF_FUNC_tcp_send_ack helper

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Add a helper to send out a tcp-ack.  It will be used in the later
bpf_dctcp implementation that requires to send out an ack
when the CE state changed.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200109004551.3900448-1-kafai@fb.com
This commit is contained in:
Martin KaFai Lau 2020-01-08 16:45:51 -08:00 committed by Alexei Starovoitov
parent 0baf26b0fc
commit 206057fe02
2 changed files with 33 additions and 2 deletions
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11
include/uapi/linux/bpf.h
View File

@ -2837,6 +2837,14 @@ union bpf_attr {
* Return
* On success, the strictly positive length of the string, including
* the trailing NUL character. On error, a negative value.
*
* int bpf_tcp_send_ack(void *tp, u32 rcv_nxt)
* Description
* Send out a tcp-ack. *tp* is the in-kernel struct tcp_sock.
* *rcv_nxt* is the ack_seq to be sent out.
* Return
* 0 on success, or a negative error in case of failure.
*
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@ -2954,7 +2962,8 @@ union bpf_attr {
FN(probe_read_user), \
FN(probe_read_kernel), \
FN(probe_read_user_str), \
FN(probe_read_kernel_str),
FN(probe_read_kernel_str), \
FN(tcp_send_ack),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call

24
net/ipv4/bpf_tcp_ca.c
View File

@ -143,11 +143,33 @@ static int bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log *log,
return NOT_INIT;
}
BPF_CALL_2(bpf_tcp_send_ack, struct tcp_sock *, tp, u32, rcv_nxt)
{
/* bpf_tcp_ca prog cannot have NULL tp */
__tcp_send_ack((struct sock *)tp, rcv_nxt);
return 0;
}
static const struct bpf_func_proto bpf_tcp_send_ack_proto = {
.func = bpf_tcp_send_ack,
.gpl_only = false,
/* In case we want to report error later */
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_BTF_ID,
.arg2_type = ARG_ANYTHING,
.btf_id = &tcp_sock_id,
};
static const struct bpf_func_proto *
bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id,
const struct bpf_prog *prog)
{
return bpf_base_func_proto(func_id);
switch (func_id) {
case BPF_FUNC_tcp_send_ack:
return &bpf_tcp_send_ack_proto;
default:
return bpf_base_func_proto(func_id);
}
}
static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = {