statistics infrastructure

This patch set replaces s390-statistics-infrastructure.patch in the -mm tree.

The common code component proposed makes a unified and inexpensive way
for providing statistics available to kernel programmers, particularly
device driver programmers. It comes with an architecture independent and
exploiter (device driver) independent user interface and allows users to
adjust gathering and processing of statistics data to their needs.

Patch 5/6 contains more detailed information in the form of a
Documentation/ file.

The most important change since s390-statistics-infrastructure.patch is
that the code doesn't just seem to be quite generic, but really is generic.

I have worked through the list of improvements pointed out by Andrew in the
following lkml thread
http://marc.theaimsgroup.com/?l=linux-kernel&m=113050...

Furthermore, I spend some extra time on comments and I fixed
some bugs, mostly related to allocation and NULL-pointer issues.

I am posting a patch for the zfcp driver, as well, which would
be the first exploiter of the statistics infrastructure. Actually, the
zfcp driver has been my test vehicle.

Patch set is against 2.6.15-rc5-git4.

Please keep me on cc: since I am not subscribed to lkml.

List of patches:

[patch 1/6] statistics infrastructure - prerequisite: scatter-gather ringbuffer
[patch 2/6] statistics infrastructure - prerequisite: parser enhancement
[patch 3/6] statistics infrastructure - prerequisite: list operation
[patch 4/6] statistics infrastructure - prerequisite: timestamp
[patch 5/6] statistics infrastructure
[patch 6/6] statistics infrastructure - exploitation: zfcp