[Xen-devel] [PATCH RFC 03/13] xen: mask event channels while changing affinity

[Konrad Rzeszutek Wilk]

On Tue, Dec 24, 2013 at 12:20:52PM +0100, Roger Pau Monne wrote:
> Event channels should be masked while chaning affinity, or else we
changing

> might get spurious/lost interrupts.
> ---
>  sys/x86/xen/xen_intr.c |   15 ++++++++++++---
>  1 files changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/sys/x86/xen/xen_intr.c b/sys/x86/xen/xen_intr.c
> index fd36e68..bc0781e 100644
> --- a/sys/x86/xen/xen_intr.c
> +++ b/sys/x86/xen/xen_intr.c
> @@ -797,7 +797,7 @@ xen_intr_assign_cpu(struct intsrc *base_isrc, u_int apic_id)
>  	struct evtchn_bind_vcpu bind_vcpu;
>  	struct xenisrc *isrc;
>  	u_int to_cpu, vcpu_id;
> -	int error;
> +	int error, masked;
>  
>  #ifdef XENHVM
>  	if (xen_vector_callback_enabled == 0)
> @@ -815,6 +815,12 @@ xen_intr_assign_cpu(struct intsrc *base_isrc, u_int apic_id)
>  		return (EINVAL);
>  	}
>  
> +	/*
> +	 * Mask the event channel port so we don't receive spurious events
> +	 * while changing affinity.
> +	 */
> +	masked = evtchn_test_and_set_mask(isrc->xi_port);
> +
>  	if ((isrc->xi_type == EVTCHN_TYPE_VIRQ) ||
>  		(isrc->xi_type == EVTCHN_TYPE_IPI)) {
>  		/*
> @@ -825,8 +831,7 @@ xen_intr_assign_cpu(struct intsrc *base_isrc, u_int apic_id)
>  		evtchn_cpu_mask_port(isrc->xi_cpu, isrc->xi_port);
>  		isrc->xi_cpu = to_cpu;
>  		evtchn_cpu_unmask_port(isrc->xi_cpu, isrc->xi_port);
> -		mtx_unlock(&xen_intr_isrc_lock);
> -		return (0);
> +		goto out;
>  	}
>  
>  	bind_vcpu.port = isrc->xi_port;
> @@ -848,6 +853,10 @@ xen_intr_assign_cpu(struct intsrc *base_isrc, u_int apic_id)
>  			evtchn_cpu_mask_port(to_cpu, isrc->xi_port);
>  		}
>  	}
> +
> +out:
> +	if (!masked)
> +		evtchn_unmask_port(isrc->xi_port);
>  	mtx_unlock(&xen_intr_isrc_lock);
>  	return (0);
>  #else
> -- 
> 1.7.7.5 (Apple Git-26)
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel at lists.xen.org
> http://lists.xen.org/xen-devel