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Date: Tue, 28 Jun 2016 09:00:13 +0200
From: Heiko Carstens <heiko.carstens@de.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>, linuxppc-dev@lists.ozlabs.org,
 linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com,
 mingo@redhat.com, mpe@ellerman.id.au, paulus@samba.org,
 benh@kernel.crashing.org, Waiman.Long@hpe.com, boqun.feng@gmail.com,
 will.deacon@arm.com, dave@stgolabs.net,
 Martin Schwidefsky <schwidefsky@de.ibm.com>,
 Christian Borntraeger <borntraeger@de.ibm.com>
Subject: Re: [PATCH 1/3] kernel/sched: introduce vcpu preempted check interface
References: <1467049290-32359-1-git-send-email-xinhui.pan@linux.vnet.ibm.com>
 <1467049290-32359-2-git-send-email-xinhui.pan@linux.vnet.ibm.com>
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On Mon, Jun 27, 2016 at 04:00:43PM +0200, Peter Zijlstra wrote:
> On Mon, Jun 27, 2016 at 01:41:28PM -0400, Pan Xinhui wrote:
> > +++ b/include/linux/sched.h
> > @@ -3293,6 +3293,15 @@ static inline void set_task_cpu(struct task_struct *p, unsigned int cpu)
> >  
> >  #endif /* CONFIG_SMP */
> >  
> > +#ifdef arch_vcpu_is_preempted
> > +static inline bool vcpu_is_preempted(int cpu)
> > +{
> > +	return arch_vcpu_is_preempted(cpu);
> > +}
> > +#else
> > +#define vcpu_is_preempted(cpu)	false
> > +#endif
> 
> #ifndef vcpu_is_preempted
> #define vcpu_is_preempted(cpu)		(false)
> #endif
> 
> Is so much simpler...
> 
> Also, please Cc the virt list so that other interested parties can
> comment, and maybe also the s390 folks.

The s390 implementation would be to simply use cpu_is_preempted() from
arch/s390/lib/spinlock.c.
It's nice that there will be a common code function for this!