Re: [PATCH v2 2/2] x86/xen: allow privcmd hypercalls to be preempted

H. Peter Anvin
2014-12-11T18:48:51Z

On 12/10/2014 05:03 PM, Luis R. Rodriguez wrote:
>
> This is an issue onloy for for non*-preemptive kernels.
>
> Some of Xen's hypercalls can take a long time and unfortunately for
> *non*-preemptive kernels this can be quite a bit of an issue.
> We've handled situations like this with cond_resched() before which will
> push even *non*-preemptive kernels to behave as voluntarily preemptive,
> I was not aware to what extent this was done and precedents set but
> its pretety widespread now... this then just addresses once particular
> case where this is also an issuefor but now in IRQ context.
>
> I agree its a hack but so are all the other cond_reshed() calls then.
> I don't think its a good idea to be spreading use of something like
> this everywhere but after careful review and trying toa void this
> exact code for a while I have not been able to find any other reasonable
> alternative.
>

This sounds like a patch that is completely unrelated to the rest of the
patch.

-hpa