On Sun, 2017-10-01 at 02:15 -0700, Christoph Hellwig wrote: > > - task_active_pid_ns(current)->last_pid); > > + task_active_pid_ns(current)->idr.idr_next-1); > > I think we want a well documented helper for this pattern instead > of poking into the internals. > > Also is last - 1 always the correct answer? Even with > idr_alloc_cyclic > we could wrap around, couldn't we?
Good point. I wonder if it makes sense to change the IDR code, so idr_get_cursor returns the last allocated ID? I see only two users of idr_get_cursor in the kernel, and it looks like both would work fine if idr_get_cursor returned the previously allocated value. That would require a small change to idr_alloc_cyclic, to have it start searching at a position one larger than the cursor, and maybe renaming idr->idr_next to idr->cursor, since it would now represent the last value allocated, not the next. Would that make sense? -- All Rights Reversed.
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