Re: [PATCH] for_each_possible_cpu [1/19] defines for_each_possible_cpu

[Nick Piggin]

Andrew Morton wrote:
> Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote:

> > for_each_cpu() effectively is for_each_possible_cpu() as far as
> > generic code is concerned. In other words, nobody would ever expect
> > for_each_cpu to return an _impossible_ CPU, thus you are just
> > adding a redundant element to the name.
>
>
> We've had various screwups and confusions with these things.  I think the
> new naming is good - it makes developers _think_ before they use it. 
> Instead of "I want to touch all the CPUs, gee that looks right" they'll
> have to stop and decide whether they want to access the online, possible or
> present ones and then they'll (hopefully) have a little think about what
> happens when CPUs migrate between those states.

I think screwups probably came from unclear documentation (which it was
until recently, and some implementations were plain wrong IIRC), and the
recentish introduction of cpu hotplug.

I don't see the point in this though. If people don't want to even think
about these issues, then this change isn't going to make them.

--
SUSE Labs, Novell Inc.
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