Messages in this thread | | | Date | Wed, 1 Jul 2015 23:06:24 -0400 | From | Tejun Heo <> | Subject | Re: [PATCH 44/51] writeback: implement bdi_wait_for_completion() |
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Hello, Jan.
On Wed, Jul 01, 2015 at 06:04:37PM +0200, Jan Kara wrote: > I'd find it better to extend completions to allow doing what you need. It > isn't that special. It seems it would be enough to implement > > void wait_for_completions(struct completion *x, int n); > > where @n is the number of completions to wait for. And the implementation > can stay as is, only in do_wait_for_common() we change checks for x->done == > 0 to "x->done < n". That's about it...
I don't know. While I agree that it'd be nice to have a generic event count & trigger mechanism in the kernel, I don't think extending completion is a good idea - the count then works both ways as the event counter && listener counter and effectively becomes a semaphore which usually doesn't end well. There are very few cases where we want the counter works both ways and I personally think we'd be far better served if those rare cases implement something custom rather than generic mechanism becoming cryptic trying to cover everything.
Thanks.
-- tejun
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