A simplified IDR API

Posted Feb 7, 2013 14:55 UTC (Thu) by corbet (editor, #1) [Link]

Not stupid. The relevant code is (usually) about to go under spinlock anyway, so the preemption disable isn't as big a deal as it could be. An API like you suggest could maybe work; one could also maybe split it into:

    id = idr_allocate_id(gfp_flags);  /* non-atomic context */
    idr_assign_id(id, pointer); /* Can be atomic */

That would handle the atomic association of the ID with the pointer while under lock without per-CPU stuff, but would require the IDR library to manage assigned-but-not-active IDs. With either this idea or yours, there would also have to be an idr_never_mind() function to back things out if need be.