centos man page for idr_alloc_cyclic

IDR_ALLOC_CYCLIC(9)					  Basic Kernel Library Functions				       IDR_ALLOC_CYCLIC(9)

NAME
       idr_alloc_cyclic - allocate new idr entry in a cyclical fashion

SYNOPSIS
       int idr_alloc_cyclic(struct idr * idr, void * ptr, int start, int end, gfp_t gfp_mask);

ARGUMENTS
       idr
	   the (initialized) idr

       ptr
	   pointer to be associated with the new id

       start
	   the minimum id (inclusive)

       end
	   the maximum id (exclusive, <= 0 for max)

       gfp_mask
	   memory allocation flags

DESCRIPTION
       Essentially the same as idr_alloc, but prefers to allocate progressively higher ids if it can. If the "cur" counter wraps, then it will
       start again at the "start" end of the range and allocate one that has already been used.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						       IDR_ALLOC_CYCLIC(9)