Re: [PATCH 0/3] static keys: fix test/set races

From: Ingo Molnar
Date: Sat Jun 29 2013 - 03:20:24 EST



* jbaron@xxxxxxxxxx <jbaron@xxxxxxxxxx> wrote:

> Hi,
>
> As pointed out by Andi Kleen, some static key users can be racy because they
> check the value of the key->enabled, and then subsequently update the branch
> direction. A number of call sites have 'higher' level locking that avoids this
> race, but the usage in the scheduler features does not. See:
> http://lkml.indiana.edu/hypermail/linux/kernel/1304.2/01655.html

But that's not an issue at all - switching the scheduler features is for
development and debugging only, and in some cases higher level locking
would be needed to solve it 'properly', beyond what the keys API could
give ...

So this is pretty pointless, sorry, please don't complicate this facility.

Thanks,

Ingo
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