diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 98f30b0..447b76c 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -7047,6 +7047,10 @@ enum {
 					 * to the nic when SK_BPF_CB_TX_TIMESTAMPING
 					 * feature is on.
 					 */
+	BPF_SOCK_OPS_TSTAMP_SND_HW_CB,	/* Called in hardware phase 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