linux-kernel - Re: [PATCH 6/9] xen/spinlock: Check against default value of -1 for IRQ line.

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Date:	Mon, 29 Apr 2013 14:35:19 -0400
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	Stefano Stabellini <stefano.stabellini@...citrix.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>
Subject: Re: [PATCH 6/9] xen/spinlock:  Check against default value of -1 for
 IRQ line.

On Fri, Apr 26, 2013 at 05:18:01PM +0100, Stefano Stabellini wrote:
> On Tue, 16 Apr 2013, Konrad Rzeszutek Wilk wrote:
> > The default (uninitialized) value of the IRQ line is -1.
> > Check if we already have allocated an spinlock interrupt line
> > and if somebody is trying to do it again. Also set it to -1
> > when we offline the CPU.
> > 
> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> > ---
> >  arch/x86/xen/spinlock.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
> > index f7a080e..47ae032 100644
> > --- a/arch/x86/xen/spinlock.c
> > +++ b/arch/x86/xen/spinlock.c
> > @@ -364,6 +364,9 @@ void __cpuinit xen_init_lock_cpu(int cpu)
> >  	int irq;
> >  	const char *name;
> >  
> > +	WARN(per_cpu(lock_kicker_irq, cpu) > 0, "spinlock on CPU%d exists on IRQ%d!\n",
>                   shouldn't this be >= ^
> 

Yes. Thanks for catching.
> 
> > +	     cpu, per_cpu(lock_kicker_irq, cpu));
> >
> >  	name = kasprintf(GFP_KERNEL, "spinlock%d", cpu);
> >  	irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR,
> >  				     cpu,
> > @@ -383,6 +386,7 @@ void __cpuinit xen_init_lock_cpu(int cpu)
> >  void xen_uninit_lock_cpu(int cpu)
> >  {
> >  	unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);
> > +	per_cpu(lock_kicker_irq, cpu) = -1;
> >  }
> >  
> >  void __init xen_init_spinlocks(void)
> > -- 
> > 1.8.1.4
> > 
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