From: Deepa Dinamani <deepa.kernel@gmail.com>
To: davem@davemloft.net, linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org, arnd@arndb.de, y2038@lists.linaro.org
Subject: [PATCH net-next v5 10/12] socket: Update timestamping Documentation
Date: Sat, 2 Feb 2019 07:34:52 -0800 [thread overview]
Message-ID: <20190202153454.7121-11-deepa.kernel@gmail.com> (raw)
In-Reply-To: <20190202153454.7121-1-deepa.kernel@gmail.com>
With the new y2038 safe timestamping options added, update the
documentation to reflect the changes.
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: Willem de Bruijn <willemb@google.com>
---
Documentation/networking/timestamping.txt | 43 ++++++++++++++++++++---
1 file changed, 38 insertions(+), 5 deletions(-)
diff --git a/Documentation/networking/timestamping.txt b/Documentation/networking/timestamping.txt
index 9d1432e0aaa8..bbdaf8990031 100644
--- a/Documentation/networking/timestamping.txt
+++ b/Documentation/networking/timestamping.txt
@@ -6,11 +6,21 @@ The interfaces for receiving network packages timestamps are:
* SO_TIMESTAMP
Generates a timestamp for each incoming packet in (not necessarily
monotonic) system time. Reports the timestamp via recvmsg() in a
- control message as struct timeval (usec resolution).
+ control message in usec resolution.
+ SO_TIMESTAMP is defined as SO_TIMESTAMP_NEW or SO_TIMESTAMP_OLD
+ based on the architecture type and time_t representation of libc.
+ Control message format is in struct __kernel_old_timeval for
+ SO_TIMESTAMP_OLD and in struct __kernel_sock_timeval for
+ SO_TIMESTAMP_NEW options respectively.
* SO_TIMESTAMPNS
Same timestamping mechanism as SO_TIMESTAMP, but reports the
- timestamp as struct timespec (nsec resolution).
+ timestamp as struct timespec in nsec resolution.
+ SO_TIMESTAMPNS is defined as SO_TIMESTAMPNS_NEW or SO_TIMESTAMPNS_OLD
+ based on the architecture type and time_t representation of libc.
+ Control message format is in struct timespec for SO_TIMESTAMPNS_OLD
+ and in struct __kernel_timespec for SO_TIMESTAMPNS_NEW options
+ respectively.
* IP_MULTICAST_LOOP + SO_TIMESTAMP[NS]
Only for multicast:approximate transmit timestamp obtained by
@@ -22,7 +32,7 @@ The interfaces for receiving network packages timestamps are:
timestamps for stream sockets.
-1.1 SO_TIMESTAMP:
+1.1 SO_TIMESTAMP (also SO_TIMESTAMP_OLD and SO_TIMESTAMP_NEW):
This socket option enables timestamping of datagrams on the reception
path. Because the destination socket, if any, is not known early in
@@ -31,15 +41,25 @@ same is true for all early receive timestamp options.
For interface details, see `man 7 socket`.
+Always use SO_TIMESTAMP_NEW timestamp to always get timestamp in
+struct __kernel_sock_timeval format.
-1.2 SO_TIMESTAMPNS:
+SO_TIMESTAMP_OLD returns incorrect timestamps after the year 2038
+on 32 bit machines.
+
+1.2 SO_TIMESTAMPNS (also SO_TIMESTAMPNS_OLD and SO_TIMESTAMPNS_NEW):
This option is identical to SO_TIMESTAMP except for the returned data type.
Its struct timespec allows for higher resolution (ns) timestamps than the
timeval of SO_TIMESTAMP (ms).
+Always use SO_TIMESTAMPNS_NEW timestamp to always get timestamp in
+struct __kernel_timespec format.
+
+SO_TIMESTAMPNS_OLD returns incorrect timestamps after the year 2038
+on 32 bit machines.
-1.3 SO_TIMESTAMPING:
+1.3 SO_TIMESTAMPING (also SO_TIMESTAMPING_OLD and SO_TIMESTAMPING_NEW):
Supports multiple types of timestamp requests. As a result, this
socket option takes a bitmap of flags, not a boolean. In
@@ -323,10 +343,23 @@ SO_TIMESTAMP and SO_TIMESTAMPNS records can be retrieved.
These timestamps are returned in a control message with cmsg_level
SOL_SOCKET, cmsg_type SCM_TIMESTAMPING, and payload of type
+For SO_TIMESTAMPING_OLD:
+
struct scm_timestamping {
struct timespec ts[3];
};
+For SO_TIMESTAMPING_NEW:
+
+struct scm_timestamping64 {
+ struct __kernel_timespec ts[3];
+
+Always use SO_TIMESTAMPING_NEW timestamp to always get timestamp in
+struct scm_timestamping64 format.
+
+SO_TIMESTAMPING_OLD returns incorrect timestamps after the year 2038
+on 32 bit machines.
+
The structure can return up to three timestamps. This is a legacy
feature. At least one field is non-zero at any time. Most timestamps
are passed in ts[0]. Hardware timestamps are passed in ts[2].
--
2.17.1
next prev parent reply other threads:[~2019-02-02 15:36 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-02 15:34 [PATCH net-next v5 00/12] net: y2038-safe socket timestamps Deepa Dinamani
2019-02-02 15:34 ` [PATCH net-next v5 01/12] selftests: add missing include unistd Deepa Dinamani
2019-02-02 15:34 ` [PATCH net-next v5 02/12] socket: move compat timeout handling into sock.c Deepa Dinamani
2019-02-02 15:34 ` [PATCH net-next v5 03/12] arch: Use asm-generic/socket.h when possible Deepa Dinamani
2019-02-02 15:34 ` [PATCH net-next v5 04/12] sockopt: Rename SO_TIMESTAMP* to SO_TIMESTAMP*_OLD Deepa Dinamani
2019-02-02 15:34 ` [PATCH net-next v5 05/12] arch: sparc: Override struct __kernel_old_timeval Deepa Dinamani
2019-02-02 15:34 ` [PATCH net-next v5 06/12] socket: Use old_timeval types for socket timestamps Deepa Dinamani
2019-02-02 15:34 ` [PATCH net-next v5 07/12] socket: Add struct __kernel_sock_timeval Deepa Dinamani
2019-02-02 15:34 ` [PATCH net-next v5 08/12] socket: Add SO_TIMESTAMP[NS]_NEW Deepa Dinamani
2019-02-02 15:34 ` [PATCH net-next v5 09/12] socket: Add SO_TIMESTAMPING_NEW Deepa Dinamani
2019-02-10 15:43 ` Ran Rozenstein
2019-02-11 3:21 ` Deepa Dinamani
2019-02-12 19:08 ` Deepa Dinamani
2019-02-02 15:34 ` Deepa Dinamani [this message]
2019-02-02 15:34 ` [PATCH net-next v5 11/12] socket: Rename SO_RCVTIMEO/ SO_SNDTIMEO with _OLD suffixes Deepa Dinamani
2019-02-06 11:58 ` Michael Ellerman
2019-02-02 15:34 ` [PATCH net-next v5 12/12] sock: Add SO_RCVTIMEO_NEW and SO_SNDTIMEO_NEW Deepa Dinamani
2019-02-02 17:15 ` Oliver Hartkopp
2019-02-03 2:47 ` Deepa Dinamani
2019-02-06 11:56 ` Michael Ellerman
2019-02-09 1:44 ` Deepa Dinamani
2019-02-10 22:12 ` Michael Ellerman
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