Messages in this thread | | | Date | Tue, 01 Dec 2009 14:09:50 +0900 | From | Tejun Heo <> | Subject | Re: [PATCH] percpu: explain quick paths in pcpu_[de]populate_chunk() |
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On 12/01/2009 02:00 PM, Tejun Heo wrote: > I thought about that but didn't want to open code the special and > fairly complex loop construct used there. To me, it seemed using the > same loop construct would be much less error-prone than open coding > the loop mostly because those two special cases are the only place > where that is necessary. Maybe we can add pcpu_first_[un]pop_region() > macros and use them there but is the first iteration check that bad > even with sufficient explanations?
So, something like the following.
#define pcpu_first_unpop_region(chunk, rs, re, start, end) do { \ (rs) = (start); \ pcpu_next_unpop((chunk), &(rs), &(re), (end)); \ } while (0)
#define pcpu_for_each_unpop_region(chunk, rs, re, start, end) \ for (pcpu_first_unpop_region(chunk, rs, re, start, end); \ (rs) < (re); \ (rs) = (re) + 1, pcpu_next_unpop((chunk), &(rs), &(re), (end)))
#define pcpu_first_pop_region(chunk, rs, re, start, end) do { \ (rs) = (start); \ pcpu_next_pop((chunk), &(rs), &(re), (end)); \ } while (0)
#define pcpu_for_each_pop_region(chunk, rs, re, start, end) \ for (pcpu_first_pop_region(chunk, rs, re, start, end); \ (rs) < (re); \ (rs) = (re) + 1, pcpu_next_pop((chunk), &(rs), &(re), (end)))
It might be better to make these proper functions which take pointers but that makes the only two interfaces for region iterators disagree about how they take parameters.
So, I don't know. The first iteration only loop looks a bit unusual for sure but it isn't something conceptually convoluted.
Thanks.
-- tejun
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