Introduce the callback to correlate tcp_sendmsg timestamp with other
points, like SND/SW/ACK. let bpf prog trace the beginning of
tcp_sendmsg_locked() and then store the sendmsg timestamp at
the bpf_sk_storage, so that in tcp_tx_timestamp() we can correlate
the timestamp with tskey which can be found in other sending points.
More details can be found in the selftest:
The selftest uses the bpf_sk_storage to store the sendmsg timestamp at
fentry/tcp_sendmsg_locked and retrieves it back at tcp_tx_timestamp
(i.e. BPF_SOCK_OPS_TS_SND_CB added in this patch).
Signed-off-by: Jason Xing <kerneljasonxing@xxxxxxxxx>
---
include/uapi/linux/bpf.h | 7 +++++++
net/ipv4/tcp.c | 1 +
tools/include/uapi/linux/bpf.h | 7 +++++++
3 files changed, 15 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 800122a8abe5..accb3b314fff 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -7052,6 +7052,13 @@ enum {
* when SK_BPF_CB_TX_TIMESTAMPING
* feature is on.
*/
+ BPF_SOCK_OPS_TS_SND_CB, /* Called when every sendmsg syscall
+ * is triggered. For TCP, it stays
+ * in the last send process to
+ * correlate with tcp_sendmsg timestamp
+ * with other timestamping callbacks,
+ * like SND/SW/ACK.
+ */
};
/* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 3df802410ebf..a2ac57543b6d 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -501,6 +501,7 @@ static void tcp_tx_timestamp(struct sock *sk, struct sockcm_cookie *sockc)
tcb->txstamp_ack_bpf = 1;
shinfo->tx_flags |= SKBTX_BPF;
shinfo->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
+ bpf_skops_tx_timestamping(sk, skb, BPF_SOCK_OPS_TS_SND_CB);
}
}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 06e68d772989..384502996cdd 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -7045,6 +7045,13 @@ enum {
* when SK_BPF_CB_TX_TIMESTAMPING
* feature is on.
*/
+ BPF_SOCK_OPS_TS_SND_CB, /* Called when every sendmsg syscall
+ * is triggered. For TCP, it stays
+ * in the last send process to
+ * correlate with tcp_sendmsg timestamp
+ * with other timestamping callbacks,
+ * like SND/SW/ACK.
+ */
};
/* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
--
2.43.5
