From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Subject: Re: [PATCH net-next] packet: move hw/sw timestamp extraction into a small helper Date: Mon, 15 Apr 2013 19:02:03 +0200 Message-ID: <516C328B.6050408@redhat.com> References: <45719bcd37c3f11eea24c2a72c09abd9907a5072.1366022623.git.dborkman@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: David Miller , netdev@vger.kernel.org To: Willem de Bruijn Return-path: Received: from mx1.redhat.com ([209.132.183.28]:28951 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933813Ab3DORCJ (ORCPT ); Mon, 15 Apr 2013 13:02:09 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 04/15/2013 06:12 PM, Willem de Bruijn wrote: > On Mon, Apr 15, 2013 at 7:41 AM, Daniel Borkmann wrote: >> This patch introduces a small helper function, that is used by AF_PACKET. >> Based on the flags that are passed, it extracts the packet timestamp in >> the receive path. This is merely a refactoring to remove some duplicate >> code in tpacket_rcv(), make it more readable, and to enable others to use >> this function as well. > > Good idea. I noticed that while browsing the code over the weekend, too. > > One question I have is whether the code warrants adding a static > inline to skbuff.h. Regular socket paths do not use the test, as they > return all timestamps together. (See below.) >> Cc: Willem de Bruijn >> Signed-off-by: Daniel Borkmann >> --- >> include/linux/skbuff.h | 20 ++++++++++++++++++++ >> net/packet/af_packet.c | 38 ++++---------------------------------- >> 2 files changed, 24 insertions(+), 34 deletions(-) >> >> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h >> index e27d1c7..d0d436f 100644 >> --- a/include/linux/skbuff.h >> +++ b/include/linux/skbuff.h >> @@ -33,6 +33,7 @@ >> #include >> #include >> #include >> +#include >> >> /* Don't change this without changing skb_csum_unnecessary! */ >> #define CHECKSUM_NONE 0 >> @@ -739,6 +740,25 @@ static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb) >> return &skb_shinfo(skb)->hwtstamps; >> } >> >> +static inline struct timespec skb_get_tstamp(struct sk_buff *skb, >> + unsigned int flags) >> +{ >> + struct skb_shared_hwtstamps *ts = skb_hwtstamps(skb); >> + >> + if ((flags & SOF_TIMESTAMPING_SYS_HARDWARE) && ts->syststamp.tv64) > > Also, packet sockets use the flags these SOF_... constants passed from > userspace directly, but regular socket paths convert this into socket > flags SOCK_..., so this code is more packet socket specific than it > seems. See __sock_recv_timestamp. I'd keep the function in > net/packet/af_packet.c solely for this reason, or add a comment. Hm, right. I do not really see a reason why we need to maintain this twice (introduced by 614f60fa9 ``packet_mmap: expose hw packet timestamps to network packet capture utilities''). This could also have been implemented actually with normal SOCK_ flags, i.e. since we use sock_tx_timestamp() which uses SOCK_ flags. I will respin and try to address that. >> + return ktime_to_timespec(ts->syststamp); >> + else if ((flags & SOF_TIMESTAMPING_RAW_HARDWARE) && ts->hwtstamp.tv64) >> + return ktime_to_timespec(ts->hwtstamp); >> + else if (skb->tstamp.tv64) >> + return ktime_to_timespec(skb->tstamp); >> + else { >> + struct timespec tc; >> + >> + getnstimeofday(&tc); >> + return tc; >> + } >> +} >> + >> /** >> * skb_queue_empty - check if a queue is empty >> * @list: queue head >> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c >> index 77d71f8..2a2a62e 100644 >> --- a/net/packet/af_packet.c >> +++ b/net/packet/af_packet.c >> @@ -1681,9 +1681,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, >> unsigned long status = TP_STATUS_USER; >> unsigned short macoff, netoff, hdrlen; >> struct sk_buff *copy_skb = NULL; >> - struct timeval tv; >> struct timespec ts; >> - struct skb_shared_hwtstamps *shhwtstamps = skb_hwtstamps(skb); >> >> if (skb->pkt_type == PACKET_LOOPBACK) >> goto drop; >> @@ -1767,24 +1765,16 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, >> >> skb_copy_bits(skb, 0, h.raw + macoff, snaplen); >> >> + ts = skb_get_tstamp(skb, po->tp_tstamp); >> + >> switch (po->tp_version) { >> case TPACKET_V1: >> h.h1->tp_len = skb->len; >> h.h1->tp_snaplen = snaplen; >> h.h1->tp_mac = macoff; >> h.h1->tp_net = netoff; >> - if ((po->tp_tstamp & SOF_TIMESTAMPING_SYS_HARDWARE) >> - && shhwtstamps->syststamp.tv64) >> - tv = ktime_to_timeval(shhwtstamps->syststamp); >> - else if ((po->tp_tstamp & SOF_TIMESTAMPING_RAW_HARDWARE) >> - && shhwtstamps->hwtstamp.tv64) >> - tv = ktime_to_timeval(shhwtstamps->hwtstamp); >> - else if (skb->tstamp.tv64) >> - tv = ktime_to_timeval(skb->tstamp); >> - else >> - do_gettimeofday(&tv); >> - h.h1->tp_sec = tv.tv_sec; >> - h.h1->tp_usec = tv.tv_usec; >> + h.h1->tp_sec = ts.tv_sec; >> + h.h1->tp_usec = ts.tv_nsec / NSEC_PER_USEC; >> hdrlen = sizeof(*h.h1); >> break; >> case TPACKET_V2: >> @@ -1792,16 +1782,6 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, >> h.h2->tp_snaplen = snaplen; >> h.h2->tp_mac = macoff; >> h.h2->tp_net = netoff; >> - if ((po->tp_tstamp & SOF_TIMESTAMPING_SYS_HARDWARE) >> - && shhwtstamps->syststamp.tv64) >> - ts = ktime_to_timespec(shhwtstamps->syststamp); >> - else if ((po->tp_tstamp & SOF_TIMESTAMPING_RAW_HARDWARE) >> - && shhwtstamps->hwtstamp.tv64) >> - ts = ktime_to_timespec(shhwtstamps->hwtstamp); >> - else if (skb->tstamp.tv64) >> - ts = ktime_to_timespec(skb->tstamp); >> - else >> - getnstimeofday(&ts); >> h.h2->tp_sec = ts.tv_sec; >> h.h2->tp_nsec = ts.tv_nsec; >> if (vlan_tx_tag_present(skb)) { >> @@ -1822,16 +1802,6 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, >> h.h3->tp_snaplen = snaplen; >> h.h3->tp_mac = macoff; >> h.h3->tp_net = netoff; >> - if ((po->tp_tstamp & SOF_TIMESTAMPING_SYS_HARDWARE) >> - && shhwtstamps->syststamp.tv64) >> - ts = ktime_to_timespec(shhwtstamps->syststamp); >> - else if ((po->tp_tstamp & SOF_TIMESTAMPING_RAW_HARDWARE) >> - && shhwtstamps->hwtstamp.tv64) >> - ts = ktime_to_timespec(shhwtstamps->hwtstamp); >> - else if (skb->tstamp.tv64) >> - ts = ktime_to_timespec(skb->tstamp); >> - else >> - getnstimeofday(&ts); >> h.h3->tp_sec = ts.tv_sec; >> h.h3->tp_nsec = ts.tv_nsec; >> hdrlen = sizeof(*h.h3); >> -- >> 1.7.11.7 >>