Re: [Xen-devel] [PATCH for 4.5] xen/arm: Initialize the domain vgic lock

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2014-12-18 at 12:05 +0000, Julien Grall wrote:
> Hi Ian,
> 
> On 18/12/2014 09:47, Ian Campbell wrote:
> > On Wed, 2014-12-17 at 15:40 +0000, Julien Grall wrote:
> >> The domain vgic lock is used uninitialized.
> >>
> >> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> >
> > Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> >
> >> ---
> >>      This is a bug fix for Xen 4.5 and Xen 4.4. The vgic lock is used
> >>      unitialized. Luckily we only use the field "raw" which is reset to 0
> >>      during the domain allocation.
> >>
> >>      There is no harm to apply for Xen 4.5 because it will correctly set
> >>      the spin_lock structure for a later usage.
> >
> > By your above reasoning there is also no point, is there? That said, I
> > think we should take this since as you say it is harmless and good
> > practice to initialise spinlocks even if not strictly necessary.
> 
> It's necessary to initialize spinlocks, not all the field of the 
> spinlock is using the value 0 at initialization time.

You said "...we only use the field "raw" which is reset to 0...". Was
that statement inaccurate?

> What I meant if the current usage is fine. But if we want to debug 
> spinlock, it won't work.
> 
> Regards,
> 



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