Messages in this thread | | | Date | Mon, 1 Oct 2012 17:47:29 -0700 | From | Kent Overstreet <> | Subject | Re: [RFC, PATCH] Extensible AIO interface |
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On Mon, Oct 01, 2012 at 04:44:39PM -0700, Zach Brown wrote: > And what about duplicate instances of a given attribute id? Use the > first? The last? Error? Depends on the id?
I thought of a better idea, instead of explicitly checking for disallowed dups:
We want to return -ENOTHANDLED for not handled attributes anyways, so let's just do that for dups - that'll catch erronious usage just fine and a generic mechanism's better than a one off hack any day.
This does mean we can't punt on return values, which isn't a bad thing.
Also, if we've got duplicate attributes userspace needs to be able to figure out which return value was for which attribute.
Two possibilities: one, return values come out in the same order attributes went in. That'd work, but I dislike the subtlety and I expect it'd be a pain for userspace.
Instead, let's just stick a u64 cookie in the attribute and include that in the return, just like we do everywhere else.
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