Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r237259 r237260 r237329:
Allow users with RO privilege to the device to read the RO attributes. [0]
Add __unused macros to appropriate places in order to allow building
with WARNS=6 on base gcc, gcc46, and clang

PR: bin/167302 [0]
Approved by: cperciva (implicit)

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Contrary to when returning in all-good cases at the end of functions we
did not free memory (1) or close the file descriptor (2) in error cases.

Reported by: Mark Johnston (1)
Reported by: attilio (2)
Reviewed by: jhb
Sponsored by: Sandvine Incorporated
MFC after: 1 week

Handle malloc() failures more gracefully by error'ing out rather than
segfaulting.

Submitted by: gcooper
MFC after: 1 week

- Save errno values before calling warn(3) so that errors are correctly
reported.
- Use powerof2() from <sys/param.h> rather than a copy and paste version.

Submitted by: gcooper
MFC after: 1 week

ntroduce mfiutil, a basic utility for managing LSI SAS-RAID & Dell PERC5/6
controllers. Controller, array, and drive status can be checked, basic
attributes can be changed, and arrays and spares can be created and deleted.
Controller firmware can also be flashed.

This does not replace MegaCLI, found in ports, as that is officially sanctioned
and supported by LSI and includes vastly more functionality. However, mfiutil
is open source and guaranteed to provide basic functionality, which can be
especially useful if you have a problem and can't get MegaCLI to work.

Approved by: re
Obtained from: Yahoo! Inc.