Patch Synopsis:

RTF Get Sizes/Free/et al patch.. for the released version of rt-linux v3.1


RT-Linux Version:

rtlinux-3.1 (as distrubuted to the commmunity at large)


Author: 

Calin A. Culianu (calin@rtlab.org)


Description:

This patch is a proof of concept/feature request for the rt-linux team at 
fsmlabs.  I (and maybe some other people?) thought it would be useful if 
an RTF were queryable from the kernel/userland with respect to buffer
size, current length, and bytes free.  As such, three functions, two
ioctls, and 1 configure option were added.

Files modified were:

scripts/config.in   -- added the configure option CONFIG_RTF_EXTRA_QUERYABLE
doc/Configure.helpa -- added a description of the above option
include/rtl_fifo.h  -- added function prototypes and some IOCTL constants
fifos/rtl_fifo.c    -- added 3 functions: rtf_free(), rtf_bufsize(), and 
                       rtf_length().  Also added two ioctls in the
		       rtf_ioctl() function (IOCTL_RTF_GET_BUFSIZE and
		       IOCTL_RTF_GET_FREE).

The code I added is small and reasonably well commented.  I tried to 
stick to the style of the existing code.  I have tested this functionality
both from userland and kernel space and everything should be fine.  I
also wrote the 3 functions to be SMP-safe (via judicious use of spin locks).
This is also in conformance with existing code.

Please let me know if the patch is accepted, and thank you for your time!

-Calin
