From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.xen@gmail.com>
Subject: Re: [PATCH 2/2] x86: fix RCU locking in
 PHYSDEVOP_get_free_pirq
Date: Wed, 05 Sep 2012 14:53:18 +0100
Message-ID: <CC6D17DE.3DCD9%keir.xen@gmail.com>
References: <504765830200007800098E5D@nat28.tlf.novell.com>
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To: Jan Beulich <JBeulich@suse.com>, xen-devel <xen-devel@lists.xen.org>
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On 05/09/2012 13:45, "Jan Beulich" <JBeulich@suse.com> 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