svn commit: r352231 - head/lib/libc/sys

[Alan Somers]

Author: asomers
Date: Wed Sep 11 19:48:32 2019
New Revision: 352231
URL: https://svnweb.freebsd.org/changeset/base/352231

Log:
  getsockopt.2: clarify that SO_TIMESTAMP is not 100% reliable
  
  When SO_TIMESTAMP is set, the kernel will attempt to attach a timestamp as
  ancillary data to each IP datagram that is received on the socket. However,
  it may fail, for example due to insufficient memory. In that case the
  packet will still be received but not timestamp will be attached.
  
  Reviewed by:	kib
  MFC after:	3 days
  Differential Revision:	https://reviews.freebsd.org/D21607

Modified:
  head/lib/libc/sys/getsockopt.2

Modified: head/lib/libc/sys/getsockopt.2
==============================================================================
--- head/lib/libc/sys/getsockopt.2	Wed Sep 11 19:29:40 2019	(r352230)
+++ head/lib/libc/sys/getsockopt.2	Wed Sep 11 19:48:32 2019	(r352231)
@@ -28,7 +28,7 @@
 .\"     @(#)getsockopt.2	8.4 (Berkeley) 5/2/95
 .\" $FreeBSD$
 .\"
-.Dd February 10, 2019
+.Dd September 11, 2019
 .Dt GETSOCKOPT 2
 .Os
 .Sh NAME
@@ -431,7 +431,8 @@ option is enabled on a
 .Dv SOCK_DGRAM
 socket, the
 .Xr recvmsg 2
-call will return a timestamp corresponding to when the datagram was received.
+call may return a timestamp corresponding to when the datagram was received.
+However, it may not, for example due to a resource shortage.
 The
 .Va msg_control
 field in the