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

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

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)
> 
> 
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> http://lists.xen.org/xen-devel

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