Re: [PATCH v2 08/14] KVM: x86: remove notifiers from PIT discard policy

[Radim KrÄmÃÅ]

2016-02-19 16:06+0100, Paolo Bonzini:
> On 19/02/2016 16:04, Radim KrÄmÃÅ wrote:
>>>> ... so in patch 7 concurrent _writes_ of reinject are protected by the
>>>> lock, but reads are done outside it (in pit_timer_fn).  WDYT about
>>>> making reinject an atomic_t?
>> There was/is no harm in having reinject non-atomic.  This patch added
>> notifiers, which is the reason for re-introducing a mutex.
>> 
>> Userspace can (and SHOULDN'T) call this function multiple times,
>> concurrently, so the mutex prevents a situations where, e.g. only one
>> notifier is registered in the end.
> 
> Yes, I understand why you added the mutex here; good catch indeed.  The
> atomic_t is just to show that it's okay to read it outside the lock.
> It's just for a bit of extra documentation.

Hm, good point.  I will add it.  Thanks.