Commit b50a5c70 authored by Miroslav Lichvar's avatar Miroslav Lichvar Committed by David S. Miller
Browse files

net: allow simultaneous SW and HW transmit timestamping 



Add SOF_TIMESTAMPING_OPT_TX_SWHW option to allow an outgoing packet to
be looped to the socket's error queue with a software timestamp even
when a hardware transmit timestamp is expected to be provided by the
driver.

Applications using this option will receive two separate messages from
the error queue, one with a software timestamp and the other with a
hardware timestamp. As the hardware timestamp is saved to the shared skb
info, which may happen before the first message with software timestamp
is received by the application, the hardware timestamp is copied to the
SCM_TIMESTAMPING control message only when the skb has no software
timestamp or it is an incoming packet.

While changing sw_tx_timestamp(), inline it in skb_tx_timestamp() as
there are no other users.

CC: Richard Cochran <richardcochran@gmail.com>
CC: Willem de Bruijn <willemb@google.com>
Signed-off-by: default avatarMiroslav Lichvar <mlichvar@redhat.com>
Acked-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 67953d47

Documentation/networking/timestamping.txt

+8 −0
Original line number Diff line number Diff line
@@ -203,6 +203,14 @@ SOF_TIMESTAMPING_OPT_PKTINFO: 
  enabled and the driver is using NAPI. The struct contains also two

  other fields, but they are reserved and undefined.



SOF_TIMESTAMPING_OPT_TX_SWHW:



  Request both hardware and software timestamps for outgoing packets

  when SOF_TIMESTAMPING_TX_HARDWARE and SOF_TIMESTAMPING_TX_SOFTWARE

  are enabled at the same time. If both timestamps are generated,

  two separate messages will be looped to the socket's error queue,

  each containing just one timestamp.



New applications are encouraged to pass SOF_TIMESTAMPING_OPT_ID to

disambiguate timestamps and SOF_TIMESTAMPING_OPT_TSONLY to operate

regardless of the setting of sysctl net.core.tstamp_allow_data.

include/linux/skbuff.h

+2 −8
Original line number Diff line number Diff line
@@ -3259,13 +3259,6 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb, 
void skb_tstamp_tx(struct sk_buff *orig_skb,

		   struct skb_shared_hwtstamps *hwtstamps);



static inline void sw_tx_timestamp(struct sk_buff *skb)

{

	if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP &&

	    !(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))

		skb_tstamp_tx(skb, NULL);

}



/**

 * skb_tx_timestamp() - Driver hook for transmit timestamping

 *
@@ -3281,7 +3274,8 @@ static inline void sw_tx_timestamp(struct sk_buff *skb) 
static inline void skb_tx_timestamp(struct sk_buff *skb)

{

	skb_clone_tx_timestamp(skb);

	sw_tx_timestamp(skb);

	if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP)

		skb_tstamp_tx(skb, NULL);

}



/**

include/uapi/linux/net_tstamp.h

+2 −1
Original line number Diff line number Diff line
@@ -28,8 +28,9 @@ enum { 
	SOF_TIMESTAMPING_OPT_TSONLY = (1<<11),

	SOF_TIMESTAMPING_OPT_STATS = (1<<12),

	SOF_TIMESTAMPING_OPT_PKTINFO = (1<<13),

	SOF_TIMESTAMPING_OPT_TX_SWHW = (1<<14),



	SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_OPT_PKTINFO,

	SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_OPT_TX_SWHW,

	SOF_TIMESTAMPING_MASK = (SOF_TIMESTAMPING_LAST - 1) |

				 SOF_TIMESTAMPING_LAST

};

net/core/skbuff.c

+4 −0
Original line number Diff line number Diff line
@@ -3901,6 +3901,10 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb, 
	if (!sk)

		return;



	if (!hwtstamps && !(sk->sk_tsflags & SOF_TIMESTAMPING_OPT_TX_SWHW) &&

	    skb_shinfo(orig_skb)->tx_flags & SKBTX_IN_PROGRESS)

		return;



	tsonly = sk->sk_tsflags & SOF_TIMESTAMPING_OPT_TSONLY;

	if (!skb_may_tx_timestamp(sk, tsonly))

		return;

net/socket.c

+18 −2
Original line number Diff line number Diff line
@@ -662,6 +662,19 @@ static bool skb_is_err_queue(const struct sk_buff *skb) 
	return skb->pkt_type == PACKET_OUTGOING;

}



/* On transmit, software and hardware timestamps are returned independently.

 * As the two skb clones share the hardware timestamp, which may be updated

 * before the software timestamp is received, a hardware TX timestamp may be

 * returned only if there is no software TX timestamp. Ignore false software

 * timestamps, which may be made in the __sock_recv_timestamp() call when the

 * option SO_TIMESTAMP(NS) is enabled on the socket, even when the skb has a

 * hardware timestamp.

 */

static bool skb_is_swtx_tstamp(const struct sk_buff *skb, int false_tstamp)

{

	return skb->tstamp && !false_tstamp && skb_is_err_queue(skb);

}



static void put_ts_pktinfo(struct msghdr *msg, struct sk_buff *skb)

{

	struct scm_ts_pktinfo ts_pktinfo;
@@ -691,14 +704,16 @@ void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk, 
{

	int need_software_tstamp = sock_flag(sk, SOCK_RCVTSTAMP);

	struct scm_timestamping tss;

	int empty = 1;

	int empty = 1, false_tstamp = 0;

	struct skb_shared_hwtstamps *shhwtstamps =

		skb_hwtstamps(skb);



	/* Race occurred between timestamp enabling and packet

	   receiving.  Fill in the current time for now. */

	if (need_software_tstamp && skb->tstamp == 0)

	if (need_software_tstamp && skb->tstamp == 0) {

		__net_timestamp(skb);

		false_tstamp = 1;

	}



	if (need_software_tstamp) {

		if (!sock_flag(sk, SOCK_RCVTSTAMPNS)) {
@@ -720,6 +735,7 @@ void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk, 
		empty = 0;

	if (shhwtstamps &&

	    (sk->sk_tsflags & SOF_TIMESTAMPING_RAW_HARDWARE) &&

	    !skb_is_swtx_tstamp(skb, false_tstamp) &&

	    ktime_to_timespec_cond(shhwtstamps->hwtstamp, tss.ts + 2)) {

		empty = 0;

		if ((sk->sk_tsflags & SOF_TIMESTAMPING_OPT_PKTINFO) &&

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