Re: [Xen-devel] [PATCH 2/2] x86: fix RCU locking in PHYSDEVOP_get_free_pirq

[Keir Fraser <keir.xen@xxxxxxxxx>]

On 05/09/2012 13:45, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:

>>> Apart from properly pairing locks with unlocks, also reduce the lock
>>> scope - no need to do the copy_{from,to}_guest()-s inside the protected
>>> region.
>>> 
>>> I actually wonder whether the RCU locks are needed here at all.
>> 
>> If it's a path that only acts on current domain, then no.
> 
> So for what case does rcu_lock_current_domain() then exist at all?

To match an unconditional rcu_unlock_domain() on exit paths, for operations
which can either be on current->domain or on a rcu_lock_domain_by_id().

 -- Keir



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