[PATCH 0/2] A kernel tracing interface

[David Wilder <dwilder@us.ibm.com>]

These patches provide a kernel tracing interface called "trace".

The motivation for "trace" is to:
- Provide a simple set of tracing primitives that will utilize the high-
  performance and low-overhead of relayfs for passing traces data from
  kernel to user space.
- Provide a common user interface for managing kernel traces.
- Allow for binary as well as ascii trace data.
- Incorporate features from the systemtap runtime that are
  useful to others.

History- Versions of this code have been submitted for review under
a couple of different names.  The original submission was called UTT,
it was later re-submitted as GTSC.   Christoph Hellwig commented "The
code looks fine ...but the name is just dumb".  Following Christoph's
advice, I changed the name to simply "Trace".

This patch addresses review comments made by Christoph Hellwig and Mathieu
Desnoyers.  Changes include the addition of a mutex and synchronization
protecting trace state changes (using RCU) and the reduction of the
number of exports.

Patches are against 2.6.23-rc4-mm1

Required patches:
1/2 Trace code and documentation
2/2 Relay reset consumed  (required for trace's "rewind" feature")

Signed-off-by: David Wilder <dwilder@us.ibm.com>