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sock: enable timestamping using control messages 

Currently, SOL_TIMESTAMPING can only be enabled using setsockopt.
This is very costly when users want to sample writes to gather
tx timestamps.

Add support for enabling SO_TIMESTAMPING via control messages by
using tsflags added in `struct sockcm_cookie` (added in the previous
patches in this series) to set the tx_flags of the last skb created in
a sendmsg. With this patch, the timestamp recording bits in tx_flags
of the skbuff is overridden if SO_TIMESTAMPING is passed in a cmsg.

Please note that this is only effective for overriding the recording
timestamps flags. Users should enable timestamp reporting (e.g.,
SOF_TIMESTAMPING_SOFTWARE | SOF_TIMESTAMPING_OPT_ID) using
socket options and then should ask for SOF_TIMESTAMPING_TX_*
using control messages per sendmsg to sample timestamps for each
write.

Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Soheil Hassas Yeganeh 2016-04-02 23:08:12 -04:00 committed by David S. Miller
parent ad1e46a837
commit c14ac9451c
16 changed files with 93 additions and 49 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/net/tun.c
View File

@ -861,7 +861,8 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
goto drop;
if (skb->sk && sk_fullsock(skb->sk)) {
sock_tx_timestamp(skb->sk, &skb_shinfo(skb)->tx_flags);
sock_tx_timestamp(skb->sk, skb->sk->sk_tsflags,
&skb_shinfo(skb)->tx_flags);
sw_tx_timestamp(skb);
}

6
include/net/ipv6.h
View File

@ -867,7 +867,8 @@ int ip6_append_data(struct sock *sk,
int odd, struct sk_buff *skb),
void *from, int length, int transhdrlen, int hlimit,
int tclass, struct ipv6_txoptions *opt, struct flowi6 *fl6,
struct rt6_info *rt, unsigned int flags, int dontfrag);
struct rt6_info *rt, unsigned int flags, int dontfrag,
const struct sockcm_cookie *sockc);
int ip6_push_pending_frames(struct sock *sk);
@ -884,7 +885,8 @@ struct sk_buff *ip6_make_skb(struct sock *sk,
void *from, int length, int transhdrlen,
int hlimit, int tclass, struct ipv6_txoptions *opt,
struct flowi6 *fl6, struct rt6_info *rt,
unsigned int flags, int dontfrag);
unsigned int flags, int dontfrag,
const struct sockcm_cookie *sockc);
static inline struct sk_buff *ip6_finish_skb(struct sock *sk)
{

10
include/net/sock.h
View File

@ -2057,19 +2057,21 @@ static inline void sock_recv_ts_and_drops(struct msghdr *msg, struct sock *sk,
sk->sk_stamp = skb->tstamp;
}
void __sock_tx_timestamp(const struct sock *sk, __u8 *tx_flags);
void __sock_tx_timestamp(__u16 tsflags, __u8 *tx_flags);
/**
* sock_tx_timestamp - checks whether the outgoing packet is to be time stamped
* @sk: socket sending this packet
* @tsflags: timestamping flags to use
* @tx_flags: completed with instructions for time stamping
*
* Note : callers should take care of initial *tx_flags value (usually 0)
*/
static inline void sock_tx_timestamp(const struct sock *sk, __u8 *tx_flags)
static inline void sock_tx_timestamp(const struct sock *sk, __u16 tsflags,
__u8 *tx_flags)
{
if (unlikely(sk->sk_tsflags))
__sock_tx_timestamp(sk, tx_flags);
if (unlikely(tsflags))
__sock_tx_timestamp(tsflags, tx_flags);
if (unlikely(sock_flag(sk, SOCK_WIFI_STATUS)))
*tx_flags |= SKBTX_WIFI_STATUS;
}

2
net/can/raw.c
View File

@ -755,7 +755,7 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
if (err < 0)
goto free_skb;
sock_tx_timestamp(sk, &skb_shinfo(skb)->tx_flags);
sock_tx_timestamp(sk, sk->sk_tsflags, &skb_shinfo(skb)->tx_flags);
skb->dev = dev;
skb->sk = sk;

5
net/ipv4/ping.c
View File

@ -737,6 +737,7 @@ static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
/* no remote port */
}
ipc.sockc.tsflags = sk->sk_tsflags;
ipc.addr = inet->inet_saddr;
ipc.opt = NULL;
ipc.oif = sk->sk_bound_dev_if;
@ -744,8 +745,6 @@ static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
ipc.ttl = 0;
ipc.tos = -1;
sock_tx_timestamp(sk, &ipc.tx_flags);
if (msg->msg_controllen) {
err = ip_cmsg_send(sk, msg, &ipc, false);
if (unlikely(err)) {
@ -768,6 +767,8 @@ static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
rcu_read_unlock();
}
sock_tx_timestamp(sk, ipc.sockc.tsflags, &ipc.tx_flags);
saddr = ipc.addr;
ipc.addr = faddr = daddr;

11
net/ipv4/raw.c
View File

@ -339,8 +339,8 @@ int raw_rcv(struct sock *sk, struct sk_buff *skb)
static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
struct msghdr *msg, size_t length,
struct rtable **rtp,
unsigned int flags)
struct rtable **rtp, unsigned int flags,
const struct sockcm_cookie *sockc)
{
struct inet_sock *inet = inet_sk(sk);
struct net *net = sock_net(sk);
@ -379,7 +379,7 @@ static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
skb->ip_summed = CHECKSUM_NONE;
sock_tx_timestamp(sk, &skb_shinfo(skb)->tx_flags);
sock_tx_timestamp(sk, sockc->tsflags, &skb_shinfo(skb)->tx_flags);
skb->transport_header = skb->network_header;
err = -EFAULT;
@ -540,6 +540,7 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
daddr = inet->inet_daddr;
}
ipc.sockc.tsflags = sk->sk_tsflags;
ipc.addr = inet->inet_saddr;
ipc.opt = NULL;
ipc.tx_flags = 0;
@ -638,10 +639,10 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
if (inet->hdrincl)
err = raw_send_hdrinc(sk, &fl4, msg, len,
&rt, msg->msg_flags);
&rt, msg->msg_flags, &ipc.sockc);
else {
sock_tx_timestamp(sk, &ipc.tx_flags);
sock_tx_timestamp(sk, ipc.sockc.tsflags, &ipc.tx_flags);
if (!ipc.addr)
ipc.addr = fl4.daddr;

20
net/ipv4/tcp.c
View File

@ -428,13 +428,13 @@ void tcp_init_sock(struct sock *sk)
}
EXPORT_SYMBOL(tcp_init_sock);
static void tcp_tx_timestamp(struct sock *sk, struct sk_buff *skb)
static void tcp_tx_timestamp(struct sock *sk, u16 tsflags, struct sk_buff *skb)
{
if (sk->sk_tsflags) {
if (sk->sk_tsflags || tsflags) {
struct skb_shared_info *shinfo = skb_shinfo(skb);
struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
sock_tx_timestamp(sk, &shinfo->tx_flags);
sock_tx_timestamp(sk, tsflags, &shinfo->tx_flags);
if (shinfo->tx_flags & SKBTX_ANY_TSTAMP)
shinfo->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
tcb->txstamp_ack = !!(shinfo->tx_flags & SKBTX_ACK_TSTAMP);
@ -959,7 +959,7 @@ static ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
offset += copy;
size -= copy;
if (!size) {
tcp_tx_timestamp(sk, skb);
tcp_tx_timestamp(sk, sk->sk_tsflags, skb);
goto out;
}
@ -1079,6 +1079,7 @@ int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
{
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb;
struct sockcm_cookie sockc;
int flags, err, copied = 0;
int mss_now = 0, size_goal, copied_syn = 0;
bool sg;
@ -1121,6 +1122,15 @@ int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
/* 'common' sending to sendq */
}
sockc.tsflags = sk->sk_tsflags;
if (msg->msg_controllen) {
err = sock_cmsg_send(sk, msg, &sockc);
if (unlikely(err)) {
err = -EINVAL;
goto out_err;
}
}
/* This should be in poll */
sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
@ -1239,7 +1249,7 @@ int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
copied += copy;
if (!msg_data_left(msg)) {
tcp_tx_timestamp(sk, skb);
tcp_tx_timestamp(sk, sockc.tsflags, skb);
goto out;
}

7
net/ipv4/udp.c
View File

@ -1027,12 +1027,11 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
*/
connected = 1;
}
ipc.sockc.tsflags = sk->sk_tsflags;
ipc.addr = inet->inet_saddr;
ipc.oif = sk->sk_bound_dev_if;
sock_tx_timestamp(sk, &ipc.tx_flags);
if (msg->msg_controllen) {
err = ip_cmsg_send(sk, msg, &ipc, sk->sk_family == AF_INET6);
if (unlikely(err)) {
@ -1059,6 +1058,8 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
saddr = ipc.addr;
ipc.addr = faddr = daddr;
sock_tx_timestamp(sk, ipc.sockc.tsflags, &ipc.tx_flags);
if (ipc.opt && ipc.opt->opt.srr) {
if (!daddr)
return -EINVAL;

6
net/ipv6/icmp.c
View File

@ -400,6 +400,7 @@ static void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info)
struct icmp6hdr tmp_hdr;
struct flowi6 fl6;
struct icmpv6_msg msg;
struct sockcm_cookie sockc_unused = {0};
int iif = 0;
int addr_type = 0;
int len;
@ -527,7 +528,7 @@ static void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info)
len + sizeof(struct icmp6hdr),
sizeof(struct icmp6hdr), hlimit,
np->tclass, NULL, &fl6, (struct rt6_info *)dst,
MSG_DONTWAIT, np->dontfrag);
MSG_DONTWAIT, np->dontfrag, &sockc_unused);
if (err) {
ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTERRORS);
ip6_flush_pending_frames(sk);
@ -566,6 +567,7 @@ static void icmpv6_echo_reply(struct sk_buff *skb)
int hlimit;
u8 tclass;
u32 mark = IP6_REPLY_MARK(net, skb->mark);
struct sockcm_cookie sockc_unused = {0};
saddr = &ipv6_hdr(skb)->daddr;
@ -617,7 +619,7 @@ static void icmpv6_echo_reply(struct sk_buff *skb)
err = ip6_append_data(sk, icmpv6_getfrag, &msg, skb->len + sizeof(struct icmp6hdr),
sizeof(struct icmp6hdr), hlimit, tclass, NULL, &fl6,
(struct rt6_info *)dst, MSG_DONTWAIT,
np->dontfrag);
np->dontfrag, &sockc_unused);
if (err) {
ICMP6_INC_STATS_BH(net, idev, ICMP6_MIB_OUTERRORS);

15
net/ipv6/ip6_output.c
View File

@ -1258,7 +1258,8 @@ static int __ip6_append_data(struct sock *sk,
int getfrag(void *from, char *to, int offset,
int len, int odd, struct sk_buff *skb),
void *from, int length, int transhdrlen,
unsigned int flags, int dontfrag)
unsigned int flags, int dontfrag,
const struct sockcm_cookie *sockc)
{
struct sk_buff *skb, *skb_prev = NULL;
unsigned int maxfraglen, fragheaderlen, mtu, orig_mtu;
@ -1329,7 +1330,7 @@ static int __ip6_append_data(struct sock *sk,
csummode = CHECKSUM_PARTIAL;
if (sk->sk_type == SOCK_DGRAM || sk->sk_type == SOCK_RAW) {
sock_tx_timestamp(sk, &tx_flags);
sock_tx_timestamp(sk, sockc->tsflags, &tx_flags);
if (tx_flags & SKBTX_ANY_SW_TSTAMP &&
sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
tskey = sk->sk_tskey++;
@ -1565,7 +1566,8 @@ int ip6_append_data(struct sock *sk,
int odd, struct sk_buff *skb),
void *from, int length, int transhdrlen, int hlimit,
int tclass, struct ipv6_txoptions *opt, struct flowi6 *fl6,
struct rt6_info *rt, unsigned int flags, int dontfrag)
struct rt6_info *rt, unsigned int flags, int dontfrag,
const struct sockcm_cookie *sockc)
{
struct inet_sock *inet = inet_sk(sk);
struct ipv6_pinfo *np = inet6_sk(sk);
@ -1593,7 +1595,8 @@ int ip6_append_data(struct sock *sk,
return __ip6_append_data(sk, fl6, &sk->sk_write_queue, &inet->cork.base,
&np->cork, sk_page_frag(sk), getfrag,
from, length, transhdrlen, flags, dontfrag);
from, length, transhdrlen, flags, dontfrag,
sockc);
}
EXPORT_SYMBOL_GPL(ip6_append_data);
@ -1752,7 +1755,7 @@ struct sk_buff *ip6_make_skb(struct sock *sk,
int hlimit, int tclass,
struct ipv6_txoptions *opt, struct flowi6 *fl6,
struct rt6_info *rt, unsigned int flags,
int dontfrag)
int dontfrag, const struct sockcm_cookie *sockc)
{
struct inet_cork_full cork;
struct inet6_cork v6_cork;
@ -1779,7 +1782,7 @@ struct sk_buff *ip6_make_skb(struct sock *sk,
err = __ip6_append_data(sk, fl6, &queue, &cork.base, &v6_cork,
&current->task_frag, getfrag, from,
length + exthdrlen, transhdrlen + exthdrlen,
flags, dontfrag);
flags, dontfrag, sockc);
if (err) {
__ip6_flush_pending_frames(sk, &queue, &cork, &v6_cork);
return ERR_PTR(err);

3
net/ipv6/ping.c
View File

@ -62,6 +62,7 @@ static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
struct dst_entry *dst;
struct rt6_info *rt;
struct pingfakehdr pfh;
struct sockcm_cookie junk = {0};
pr_debug("ping_v6_sendmsg(sk=%p,sk->num=%u)\n", inet, inet->inet_num);
@ -144,7 +145,7 @@ static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
err = ip6_append_data(sk, ping_getfrag, &pfh, len,
0, hlimit,
np->tclass, NULL, &fl6, rt,
MSG_DONTWAIT, np->dontfrag);
MSG_DONTWAIT, np->dontfrag, &junk);
if (err) {
ICMP6_INC_STATS(sock_net(sk), rt->rt6i_idev,

5
net/ipv6/raw.c
View File

@ -822,8 +822,7 @@ static int rawv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
if (fl6.flowi6_oif == 0)
fl6.flowi6_oif = sk->sk_bound_dev_if;
sockc.tsflags = 0;
sockc.tsflags = sk->sk_tsflags;
if (msg->msg_controllen) {
opt = &opt_space;
memset(opt, 0, sizeof(struct ipv6_txoptions));
@ -901,7 +900,7 @@ static int rawv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
lock_sock(sk);
err = ip6_append_data(sk, raw6_getfrag, &rfv,
len, 0, hlimit, tclass, opt, &fl6, (struct rt6_info *)dst,
msg->msg_flags, dontfrag);
msg->msg_flags, dontfrag, &sockc);
if (err)
ip6_flush_pending_frames(sk);

7
net/ipv6/udp.c
View File

@ -1248,7 +1248,7 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
fl6.flowi6_oif = np->sticky_pktinfo.ipi6_ifindex;
fl6.flowi6_mark = sk->sk_mark;
sockc.tsflags = 0;
sockc.tsflags = sk->sk_tsflags;
if (msg->msg_controllen) {
opt = &opt_space;
@ -1324,7 +1324,7 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
skb = ip6_make_skb(sk, getfrag, msg, ulen,
sizeof(struct udphdr), hlimit, tclass, opt,
&fl6, (struct rt6_info *)dst,
msg->msg_flags, dontfrag);
msg->msg_flags, dontfrag, &sockc);
err = PTR_ERR(skb);
if (!IS_ERR_OR_NULL(skb))
err = udp_v6_send_skb(skb, &fl6);
@ -1351,7 +1351,8 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
err = ip6_append_data(sk, getfrag, msg, ulen,
sizeof(struct udphdr), hlimit, tclass, opt, &fl6,
(struct rt6_info *)dst,
corkreq ? msg->msg_flags|MSG_MORE : msg->msg_flags, dontfrag);
corkreq ? msg->msg_flags|MSG_MORE : msg->msg_flags, dontfrag,
&sockc);
if (err)
udp_v6_flush_pending_frames(sk);
else if (!corkreq)

2
net/l2tp/l2tp_ip6.c
View File

@ -627,7 +627,7 @@ static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
err = ip6_append_data(sk, ip_generic_getfrag, msg,
ulen, transhdrlen, hlimit, tclass, opt,
&fl6, (struct rt6_info *)dst,
msg->msg_flags, dontfrag);
msg->msg_flags, dontfrag, &sockc_unused);
if (err)
ip6_flush_pending_frames(sk);
else if (!(msg->msg_flags & MSG_MORE))

30
net/packet/af_packet.c
View File

@ -1837,6 +1837,7 @@ static int packet_sendmsg_spkt(struct socket *sock, struct msghdr *msg,
DECLARE_SOCKADDR(struct sockaddr_pkt *, saddr, msg->msg_name);
struct sk_buff *skb = NULL;
struct net_device *dev;
struct sockcm_cookie sockc;
__be16 proto = 0;
int err;
int extra_len = 0;
@ -1925,12 +1926,21 @@ static int packet_sendmsg_spkt(struct socket *sock, struct msghdr *msg,
goto out_unlock;
}
sockc.tsflags = 0;
if (msg->msg_controllen) {
err = sock_cmsg_send(sk, msg, &sockc);
if (unlikely(err)) {
err = -EINVAL;
goto out_unlock;
}
}
skb->protocol = proto;
skb->dev = dev;
skb->priority = sk->sk_priority;
skb->mark = sk->sk_mark;
sock_tx_timestamp(sk, &skb_shinfo(skb)->tx_flags);
sock_tx_timestamp(sk, sockc.tsflags, &skb_shinfo(skb)->tx_flags);
if (unlikely(extra_len == 4))
skb->no_fcs = 1;
@ -2486,7 +2496,8 @@ static int packet_snd_vnet_gso(struct sk_buff *skb,
static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
void *frame, struct net_device *dev, void *data, int tp_len,
__be16 proto, unsigned char *addr, int hlen, int copylen)
__be16 proto, unsigned char *addr, int hlen, int copylen,
const struct sockcm_cookie *sockc)
{
union tpacket_uhdr ph;
int to_write, offset, len, nr_frags, len_max;
@ -2500,7 +2511,7 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
skb->dev = dev;
skb->priority = po->sk.sk_priority;
skb->mark = po->sk.sk_mark;
sock_tx_timestamp(&po->sk, &skb_shinfo(skb)->tx_flags);
sock_tx_timestamp(&po->sk, sockc->tsflags, &skb_shinfo(skb)->tx_flags);
skb_shinfo(skb)->destructor_arg = ph.raw;
skb_reserve(skb, hlen);
@ -2624,6 +2635,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
struct sk_buff *skb;
struct net_device *dev;
struct virtio_net_hdr *vnet_hdr = NULL;
struct sockcm_cookie sockc;
__be16 proto;
int err, reserve = 0;
void *ph;
@ -2655,6 +2667,13 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
dev = dev_get_by_index(sock_net(&po->sk), saddr->sll_ifindex);
}
sockc.tsflags = 0;
if (msg->msg_controllen) {
err = sock_cmsg_send(&po->sk, msg, &sockc);
if (unlikely(err))
goto out;
}
err = -ENXIO;
if (unlikely(dev == NULL))
goto out;
@ -2712,7 +2731,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
goto out_status;
}
tp_len = tpacket_fill_skb(po, skb, ph, dev, data, tp_len, proto,
addr, hlen, copylen);
addr, hlen, copylen, &sockc);
if (likely(tp_len >= 0) &&
tp_len > dev->mtu + reserve &&
!po->has_vnet_hdr &&
@ -2851,6 +2870,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
if (unlikely(!(dev->flags & IFF_UP)))
goto out_unlock;
sockc.tsflags = 0;
sockc.mark = sk->sk_mark;
if (msg->msg_controllen) {
err = sock_cmsg_send(sk, msg, &sockc);
@ -2908,7 +2928,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
goto out_free;
}
sock_tx_timestamp(sk, &skb_shinfo(skb)->tx_flags);
sock_tx_timestamp(sk, sockc.tsflags, &skb_shinfo(skb)->tx_flags);
if (!vnet_hdr.gso_type && (len > dev->mtu + reserve + extra_len) &&
!packet_extra_vlan_len_allowed(dev, skb)) {

10
net/socket.c
View File

@ -587,20 +587,20 @@ void sock_release(struct socket *sock)
}
EXPORT_SYMBOL(sock_release);
void __sock_tx_timestamp(const struct sock *sk, __u8 *tx_flags)
void __sock_tx_timestamp(__u16 tsflags, __u8 *tx_flags)
{
u8 flags = *tx_flags;
if (sk->sk_tsflags & SOF_TIMESTAMPING_TX_HARDWARE)
if (tsflags & SOF_TIMESTAMPING_TX_HARDWARE)
flags |= SKBTX_HW_TSTAMP;
if (sk->sk_tsflags & SOF_TIMESTAMPING_TX_SOFTWARE)
if (tsflags & SOF_TIMESTAMPING_TX_SOFTWARE)
flags |= SKBTX_SW_TSTAMP;
if (sk->sk_tsflags & SOF_TIMESTAMPING_TX_SCHED)
if (tsflags & SOF_TIMESTAMPING_TX_SCHED)
flags |= SKBTX_SCHED_TSTAMP;
if (sk->sk_tsflags & SOF_TIMESTAMPING_TX_ACK)
if (tsflags & SOF_TIMESTAMPING_TX_ACK)
flags |= SKBTX_ACK_TSTAMP;
*tx_flags = flags;