From mboxrd@z Thu Jan 1 00:00:00 1970 From: Willem de Bruijn Subject: Re: [RFC PATCH 6/7] net: allow simultaneous SW and HW transmit timestamping Date: Thu, 13 Apr 2017 10:30:32 -0400 Message-ID: References: <20170412141737.5881-1-mlichvar@redhat.com> <20170412141737.5881-7-mlichvar@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Network Development , Richard Cochran , Willem de Bruijn , Soheil Hassas Yeganeh , "Keller, Jacob E" , Denny Page , Jiri Benc To: Miroslav Lichvar Return-path: Received: from mail-qk0-f194.google.com ([209.85.220.194]:36183 "EHLO mail-qk0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752534AbdDMObO (ORCPT ); Thu, 13 Apr 2017 10:31:14 -0400 Received: by mail-qk0-f194.google.com with SMTP id v75so8474378qkb.3 for ; Thu, 13 Apr 2017 07:31:14 -0700 (PDT) In-Reply-To: <20170412141737.5881-7-mlichvar@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Apr 12, 2017 at 10:17 AM, Miroslav Lichvar wrote: > Add SOF_TIMESTAMPING_OPT_MULTIMSG option to allow looping the outgoing > packet 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. > > CC: Richard Cochran > CC: Willem de Bruijn > Signed-off-by: Miroslav Lichvar > --- > Documentation/networking/timestamping.txt | 12 ++++++++++-- > include/linux/skbuff.h | 3 +-- > include/uapi/linux/net_tstamp.h | 3 ++- > net/core/skbuff.c | 4 ++++ > net/socket.c | 6 ++++++ > 5 files changed, 23 insertions(+), 5 deletions(-) > > diff --git a/Documentation/networking/timestamping.txt b/Documentation/networking/timestamping.txt > index ed04aaa..8f30385 100644 > --- a/Documentation/networking/timestamping.txt > +++ b/Documentation/networking/timestamping.txt > @@ -201,6 +201,12 @@ SOF_TIMESTAMPING_OPT_PKTINFO: > this information, it will be attached in struct scm_ts_pktinfo as > a separate control message of type SCM_TIMESTAMPING_PKTINFO. > > +SOF_TIMESTAMPING_OPT_MULTIMSG: > + > + Allow outgoing packets to be looped multiple times to the socket's > + error queue in order to receive both software and hardware transmit > + timestamps. > + It is already possible to receive multiple copies of the same message. Timestamps of type SCM_TSTAMP_SCHED will be passed for every device, virtual or physical, such as bonding. With TCP retransmits, multiple SCM_TSTAMP_SND can be observed. The name for this option is therefore not very descriptive. Perhaps SOF_TIMESTAMPING_OPT_BOTH_SW_HW. > 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. > @@ -320,8 +326,10 @@ struct scm_timestamping { > }; > > The structure can return up to three timestamps. This is a legacy > -feature. Only one field is non-zero at any time. Most timestamps > -are passed in ts[0]. Hardware timestamps are passed in ts[2]. > +feature. Most timestamps are passed in ts[0]. Hardware timestamps > +are passed in ts[2]. Incoming packets may have timestamps in both > +ts[0] and ts[2], but for outgoing packets only one field is non-zero > +at any time. > > ts[1] used to hold hardware timestamps converted to system time. > Instead, expose the hardware clock device on the NIC directly as > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h > index e91685a..0387c4b 100644 > --- a/include/linux/skbuff.h > +++ b/include/linux/skbuff.h > @@ -3302,8 +3302,7 @@ void skb_tstamp_tx(struct sk_buff *orig_skb, > > 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)) > + if (skb_shinfo(skb)->tx_flags & SKBTX_SW_TSTAMP) > skb_tstamp_tx(skb, NULL); > } > > diff --git a/include/uapi/linux/net_tstamp.h b/include/uapi/linux/net_tstamp.h > index 8397ecd..887e3ff 100644 > --- a/include/uapi/linux/net_tstamp.h > +++ b/include/uapi/linux/net_tstamp.h > @@ -27,8 +27,9 @@ enum { > SOF_TIMESTAMPING_OPT_TSONLY = (1<<11), > SOF_TIMESTAMPING_OPT_STATS = (1<<12), > SOF_TIMESTAMPING_OPT_PKTINFO = (1<<13), > + SOF_TIMESTAMPING_OPT_MULTIMSG = (1<<14), > > - SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_OPT_PKTINFO, > + SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_OPT_MULTIMSG, > SOF_TIMESTAMPING_MASK = (SOF_TIMESTAMPING_LAST - 1) | > SOF_TIMESTAMPING_LAST > }; > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > index 7ca251f..d3df8ff 100644 > --- a/net/core/skbuff.c > +++ b/net/core/skbuff.c > @@ -3863,6 +3863,10 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb, > if (!sk) > return; > > + if (!hwtstamps && !(sk->sk_tsflags & SOF_TIMESTAMPING_OPT_MULTIMSG) && > + 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; > diff --git a/net/socket.c b/net/socket.c > index 32e78de..5c9f2eb 100644 > --- a/net/socket.c > +++ b/net/socket.c > @@ -695,12 +695,18 @@ void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk, > } > } > > + /* Received packets may have both SW and HW timestamps in one control > + * message. Transmitted packets may have only one timestamp in the > + * control message, but there may be two separate messages in the error > + * queue if the SOF_TIMESTAMPING_OPT_MULTIMSG option is enabled. > + */ Unnecessary comment, and inexact given SCM_TSTAMP_SCHED and others. > memset(&tss, 0, sizeof(tss)); > if ((sk->sk_tsflags & SOF_TIMESTAMPING_SOFTWARE) && > ktime_to_timespec_cond(skb->tstamp, tss.ts + 0)) > empty = 0; > if (shhwtstamps && > (sk->sk_tsflags & SOF_TIMESTAMPING_RAW_HARDWARE) && > + (empty || !skb_is_err_queue(skb)) && > ktime_to_timespec_cond(shhwtstamps->hwtstamp, tss.ts + 2)) { > if (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_PKTINFO && > shhwtstamps->if_index) { > -- > 2.9.3 >