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Message-Id: <20240905071738.3725-2-kerneljasonxing@gmail.com>
Date: Thu, 5 Sep 2024 15:17:34 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: davem@...emloft.net,
edumazet@...gle.com,
kuba@...nel.org,
pabeni@...hat.com,
dsahern@...nel.org,
willemdebruijn.kernel@...il.com,
shuah@...nel.org,
willemb@...gle.com
Cc: linux-kselftest@...r.kernel.org,
netdev@...r.kernel.org,
Jason Xing <kernelxing@...cent.com>
Subject: [PATCH net-next v4 1/4] net-timestamp: filter out report when setting SOF_TIMESTAMPING_SOFTWARE
From: Jason Xing <kernelxing@...cent.com>
introduce a new flag SOF_TIMESTAMPING_OPT_RX_FILTER in the receive
path. User can set it with SOF_TIMESTAMPING_SOFTWARE to filter
out rx software timestamp report, especially after a process turns on
netstamp_needed_key which can time stamp every incoming skb.
Previously, we found out if an application starts first which turns on
netstamp_needed_key, then another one only passing SOF_TIMESTAMPING_SOFTWARE
could also get rx timestamp. Now we handle this case by introducing this
new flag without breaking users.
Quoting Willem to explain why we need the flag:
"why a process would want to request software timestamp reporting, but
not receive software timestamp generation. The only use I see is when
the application does request
SOF_TIMESTAMPING_SOFTWARE | SOF_TIMESTAMPING_TX_SOFTWARE."
In this way, we have two kinds of combination:
1. setting SOF_TIMESTAMPING_SOFTWARE|SOF_TIMESTAMPING_RX_SOFTWARE, it
will surely allow users to get the rx software timestamp report.
2. setting SOF_TIMESTAMPING_SOFTWARE|SOF_TIMESTAMPING_OPT_RX_FILTER
while the skb is timestamped, it will stop reporting the rx software
timestamp.
Another thing about errqueue in this patch I have a few words to say:
In this case, we need to handle the egress path carefully, or else
reporting the tx timestamp will fail. Egress path and ingress path will
finally call sock_recv_timestamp(). We have to distinguish them.
Errqueue is a good indicator to reflect the flow direction.
Suggested-by: Willem de Bruijn <willemb@...gle.com>
Reviewed-by: Willem de Bruijn <willemb@...gle.com>
Signed-off-by: Jason Xing <kernelxing@...cent.com>
---
v4
Link: https://lore.kernel.org/all/20240830153751.86895-2-kerneljasonxing@gmail.com/
1. revise the commit message and doc (Willem)
2. simplify the test statement (Jakub)
3. add Willem's reviewed-by tag (Willem)
v3
1. Willem suggested this alternative way to solve the issue, so I
added his Suggested-by tag here. Thanks!
---
Documentation/networking/timestamping.rst | 12 ++++++++++++
include/uapi/linux/net_tstamp.h | 3 ++-
net/core/sock.c | 4 ++++
net/ethtool/common.c | 1 +
net/ipv4/tcp.c | 6 ++++--
net/socket.c | 4 +++-
6 files changed, 26 insertions(+), 4 deletions(-)
diff --git a/Documentation/networking/timestamping.rst b/Documentation/networking/timestamping.rst
index 5e93cd71f99f..37ead02be3b1 100644
--- a/Documentation/networking/timestamping.rst
+++ b/Documentation/networking/timestamping.rst
@@ -266,6 +266,18 @@ SOF_TIMESTAMPING_OPT_TX_SWHW:
two separate messages will be looped to the socket's error queue,
each containing just one timestamp.
+SOF_TIMESTAMPING_OPT_RX_FILTER:
+ Used in the receive software timestamp. Enabling the flag along with
+ SOF_TIMESTAMPING_SOFTWARE will not report the rx timestamp to the
+ userspace so that it can filter out the case where one process starts
+ first which turns on netstamp_needed_key through setting generation
+ flags like SOF_TIMESTAMPING_RX_SOFTWARE, then another one only passing
+ SOF_TIMESTAMPING_SOFTWARE report flag could also get the rx timestamp.
+
+ SOF_TIMESTAMPING_OPT_RX_FILTER prevents the application from being
+ influenced by others and let the application choose whether to report
+ the timestamp in the receive path or not.
+
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.
diff --git a/include/uapi/linux/net_tstamp.h b/include/uapi/linux/net_tstamp.h
index a2c66b3d7f0f..858339d1c1c4 100644
--- a/include/uapi/linux/net_tstamp.h
+++ b/include/uapi/linux/net_tstamp.h
@@ -32,8 +32,9 @@ enum {
SOF_TIMESTAMPING_OPT_TX_SWHW = (1<<14),
SOF_TIMESTAMPING_BIND_PHC = (1 << 15),
SOF_TIMESTAMPING_OPT_ID_TCP = (1 << 16),
+ SOF_TIMESTAMPING_OPT_RX_FILTER = (1 << 17),
- SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_OPT_ID_TCP,
+ SOF_TIMESTAMPING_LAST = SOF_TIMESTAMPING_OPT_RX_FILTER,
SOF_TIMESTAMPING_MASK = (SOF_TIMESTAMPING_LAST - 1) |
SOF_TIMESTAMPING_LAST
};
diff --git a/net/core/sock.c b/net/core/sock.c
index 468b1239606c..6a93344e21cf 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -908,6 +908,10 @@ int sock_set_timestamping(struct sock *sk, int optname,
!(val & SOF_TIMESTAMPING_OPT_ID))
return -EINVAL;
+ if (val & SOF_TIMESTAMPING_RX_SOFTWARE &&
+ val & SOF_TIMESTAMPING_OPT_RX_FILTER)
+ return -EINVAL;
+
if (val & SOF_TIMESTAMPING_OPT_ID &&
!(sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)) {
if (sk_is_tcp(sk)) {
diff --git a/net/ethtool/common.c b/net/ethtool/common.c
index 781834ef57c3..6c245e59bbc1 100644
--- a/net/ethtool/common.c
+++ b/net/ethtool/common.c
@@ -427,6 +427,7 @@ const char sof_timestamping_names[][ETH_GSTRING_LEN] = {
[const_ilog2(SOF_TIMESTAMPING_OPT_TX_SWHW)] = "option-tx-swhw",
[const_ilog2(SOF_TIMESTAMPING_BIND_PHC)] = "bind-phc",
[const_ilog2(SOF_TIMESTAMPING_OPT_ID_TCP)] = "option-id-tcp",
+ [const_ilog2(SOF_TIMESTAMPING_OPT_RX_FILTER)] = "option-rx-filter",
};
static_assert(ARRAY_SIZE(sof_timestamping_names) == __SOF_TIMESTAMPING_CNT);
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 8a5680b4e786..a0c57c8b77bd 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2235,6 +2235,7 @@ void tcp_recv_timestamp(struct msghdr *msg, const struct sock *sk,
struct scm_timestamping_internal *tss)
{
int new_tstamp = sock_flag(sk, SOCK_TSTAMP_NEW);
+ u32 tsflags = READ_ONCE(sk->sk_tsflags);
bool has_timestamping = false;
if (tss->ts[0].tv_sec || tss->ts[0].tv_nsec) {
@@ -2274,14 +2275,15 @@ void tcp_recv_timestamp(struct msghdr *msg, const struct sock *sk,
}
}
- if (READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_SOFTWARE)
+ if (tsflags & SOF_TIMESTAMPING_SOFTWARE &&
+ !(tsflags & SOF_TIMESTAMPING_OPT_RX_FILTER))
has_timestamping = true;
else
tss->ts[0] = (struct timespec64) {0};
}
if (tss->ts[2].tv_sec || tss->ts[2].tv_nsec) {
- if (READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_RAW_HARDWARE)
+ if (tsflags & SOF_TIMESTAMPING_RAW_HARDWARE)
has_timestamping = true;
else
tss->ts[2] = (struct timespec64) {0};
diff --git a/net/socket.c b/net/socket.c
index fcbdd5bc47ac..f8609d649ed3 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -946,7 +946,9 @@ void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk,
memset(&tss, 0, sizeof(tss));
tsflags = READ_ONCE(sk->sk_tsflags);
- if ((tsflags & SOF_TIMESTAMPING_SOFTWARE) &&
+ if ((tsflags & SOF_TIMESTAMPING_SOFTWARE &&
+ (skb_is_err_queue(skb) ||
+ !(tsflags & SOF_TIMESTAMPING_OPT_RX_FILTER))) &&
ktime_to_timespec64_cond(skb->tstamp, tss.ts + 0))
empty = 0;
if (shhwtstamps &&
--
2.37.3
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