- Introduce the net.bpf.tscfg sysctl tree and associated code so as to make one

  aspect of time stamp configuration per interface rather than per BPF
  descriptor. Prior to this, the order in which BPF devices were opened and the
  per descriptor time stamp configuration settings could cause non-deterministic
  and unintended behaviour with respect to time stamping. With the new scheme, a
  BPF attached interface's tscfg sysctl entry can be set to "default", "none",
  "fast", "normal" or "external". Setting "default" means use the system default
  option (set with the net.bpf.tscfg.default sysctl), "none" means do not
  generate time stamps for tapped packets, "fast" means generate time stamps for
  tapped packets using a hz granularity system clock read, "normal" means
  generate time stamps for tapped packets using a full timecounter granularity
  system clock read and "external" (currently unimplemented) means use the time
  stamp provided with the packet from an underlying source.

- Utilise the recently introduced sysclock_getsnapshot() and
  sysclock_snap2bintime() KPIs to ensure the system clock is only read once per
  packet, regardless of the number of BPF descriptors and time stamp formats
  requested. Use the per BPF attached interface time stamp configuration to
  control if sysclock_getsnapshot() is called and whether the system clock read
  is fast or normal. The per BPF descriptor time stamp configuration is then
  used to control how the system clock snapshot is converted to a bintime by
  sysclock_snap2bintime().

- Remove all FAST related BPF descriptor flag variants. Performing a "fast"
  read of the system clock is now controlled per BPF attached interface using
  the net.bpf.tscfg sysctl tree.

- Update the bpf.4 man page.

Committed on behalf of Julien Ridoux and Darryl Veitch from the University of
Melbourne, Australia, as part of the FreeBSD Foundation funded "Feed-Forward
Clock Synchronization Algorithms" project.

For more information, see http://www.synclab.org/radclock/

In collaboration with:	Julien Ridoux (jridoux at unimelb edu au)

1 files changed, 10 insertions, 11 deletions

diff --git a/sys/net/bpf.h b/sys/net/bpf.h
index d4c369d..055ca5a 100644
--- a/sys/net/bpf.h
+++ b/sys/net/bpf.h
@@ -1,12 +1,17 @@
 /*-
  * Copyright (c) 1990, 1991, 1993
- *	The Regents of the University of California.  All rights reserved.
+ *	The Regents of the University of California.
+ * Copyright (c) 2011 The University of Melbourne.
+ * All rights reserved.
  *
  * This code is derived from the Stanford/CMU enet packet filter,
  * (net/enet.c) distributed as part of 4.3BSD, and code contributed
  * to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
  * Berkeley Laboratory.
  *
+ * Portions of this software were developed by Julien Ridoux at the University
+ * of Melbourne under sponsorship from the FreeBSD Foundation.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
@@ -166,25 +171,17 @@ enum bpf_direction {
 #define	BPF_T_NONE		0x0003
 #define	BPF_T_FORMAT_MASK	0x0003
 #define	BPF_T_NORMAL		0x0000
-#define	BPF_T_FAST		0x0100
-#define	BPF_T_MONOTONIC		0x0200
-#define	BPF_T_MONOTONIC_FAST	(BPF_T_FAST | BPF_T_MONOTONIC)
-#define	BPF_T_FLAG_MASK		0x0300
+#define	BPF_T_MONOTONIC		0x0100
+#define	BPF_T_FLAG_MASK		0x0100
 #define	BPF_T_FORMAT(t)		((t) & BPF_T_FORMAT_MASK)
 #define	BPF_T_FLAG(t)		((t) & BPF_T_FLAG_MASK)
 #define	BPF_T_VALID(t)						\
     ((t) == BPF_T_NONE || (BPF_T_FORMAT(t) != BPF_T_NONE &&	\
     ((t) & ~(BPF_T_FORMAT_MASK | BPF_T_FLAG_MASK)) == 0))
 
-#define	BPF_T_MICROTIME_FAST		(BPF_T_MICROTIME | BPF_T_FAST)
-#define	BPF_T_NANOTIME_FAST		(BPF_T_NANOTIME | BPF_T_FAST)
-#define	BPF_T_BINTIME_FAST		(BPF_T_BINTIME | BPF_T_FAST)
 #define	BPF_T_MICROTIME_MONOTONIC	(BPF_T_MICROTIME | BPF_T_MONOTONIC)
 #define	BPF_T_NANOTIME_MONOTONIC	(BPF_T_NANOTIME | BPF_T_MONOTONIC)
 #define	BPF_T_BINTIME_MONOTONIC		(BPF_T_BINTIME | BPF_T_MONOTONIC)
-#define	BPF_T_MICROTIME_MONOTONIC_FAST	(BPF_T_MICROTIME | BPF_T_MONOTONIC_FAST)
-#define	BPF_T_NANOTIME_MONOTONIC_FAST	(BPF_T_NANOTIME | BPF_T_MONOTONIC_FAST)
-#define	BPF_T_BINTIME_MONOTONIC_FAST	(BPF_T_BINTIME | BPF_T_MONOTONIC_FAST)
 
 /*
  * Structure prepended to each packet.
@@ -1100,6 +1097,8 @@ struct bpf_if {
 	u_int bif_hdrlen;		/* length of link header */
 	struct ifnet *bif_ifp;		/* corresponding interface */
 	struct mtx	bif_mtx;	/* mutex for interface */
+	struct sysctl_oid *tscfgoid;	/* timestamp sysctl oid for interface */
+	int tstype;			/* timestamp setting for interface */
 };
 
 void	 bpf_bufheld(struct bpf_d *d);