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[209.85.128.52]) by smtp.gmail.com with ESMTPSA id x7sm18171106eds.11.2021.05.12.07.24.44 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 12 May 2021 07:24:45 -0700 (PDT) Received: by mail-wm1-f52.google.com with SMTP id u133so1619580wmg.1 for ; Wed, 12 May 2021 07:24:44 -0700 (PDT) X-Received: by 2002:a1c:ba05:: with SMTP id k5mr7718933wmf.169.1620829484464; Wed, 12 May 2021 07:24:44 -0700 (PDT) MIME-Version: 1.0 References: <1620783082-28906-1-git-send-email-rsanger@wand.net.nz> In-Reply-To: <1620783082-28906-1-git-send-email-rsanger@wand.net.nz> From: Willem de Bruijn Date: Wed, 12 May 2021 10:24:06 -0400 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2] net: packetmmap: fix only tx timestamp on request To: Richard Sanger Cc: Network Development , Daniel Borkmann Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, May 11, 2021 at 9:32 PM Richard Sanger wrote: > > The packetmmap tx ring should only return timestamps if requested via > setsockopt PACKET_TIMESTAMP, as documented. This allows compatibility > with non-timestamp aware user-space code which checks > tp_status == TP_STATUS_AVAILABLE; not expecting additional timestamp > flags to be set in tp_status. > > Fixes: b9c32fb27170 ("packet: if hw/sw ts enabled in rx/tx ring, report which ts we got") > Cc: Daniel Borkmann > Cc: Willem de Bruijn > Signed-off-by: Richard Sanger Code LGTM. It would be good to capture more of the context: when these spurious timestamps can appear (network namespaces) and as of which commit (the one that changes orphaning). As is, I would not be able to understand the issue addressed from this commit message alone. Instead of adding context to the commit, you could also add a Link tag to the archived email thread, if you prefer. And perhaps: [PATCH net v3] net/packet: return software transmit timestamp only when requested > --- > net/packet/af_packet.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c > index ba96db1..ae906eb 100644 > --- a/net/packet/af_packet.c > +++ b/net/packet/af_packet.c > @@ -422,7 +422,8 @@ static __u32 tpacket_get_timestamp(struct sk_buff *skb, struct timespec64 *ts, > ktime_to_timespec64_cond(shhwtstamps->hwtstamp, ts)) > return TP_STATUS_TS_RAW_HARDWARE; > > - if (ktime_to_timespec64_cond(skb->tstamp, ts)) > + if ((flags & SOF_TIMESTAMPING_SOFTWARE) && > + ktime_to_timespec64_cond(skb->tstamp, ts)) > return TP_STATUS_TS_SOFTWARE; > > return 0; > @@ -2340,7 +2341,12 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, > > skb_copy_bits(skb, 0, h.raw + macoff, snaplen); > > - if (!(ts_status = tpacket_get_timestamp(skb, &ts, po->tp_tstamp))) > + /* Always timestamp; prefer an existing software timestamp taken > + * closer to the time of capture. > + */ > + ts_status = tpacket_get_timestamp(skb, &ts, > + po->tp_tstamp | SOF_TIMESTAMPING_SOFTWARE); > + if (!ts_status) > ktime_get_real_ts64(&ts); > > status |= ts_status; > -- > 2.7.4 >