Re: [PATCH 2/3] xen: cpupool: assigning a CPU to a pool can fail

[Juergen Gross <jgross@suse.com>]

On 05/06/2015 05:10 PM, Dario Faggioli wrote:
> which means such an event must be handled at the call sites
> of cpupool_assign_cpu_locked(), and the error, if occurring,
> properly propagated.
>
> Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
> Cc: Juergen Gross <jgross@suse.com>
> Cc: George Dunlap <George.Dunlap@eu.citrix.com>
> Cc: Jan Beulich <jbeulich@suse.com>
> Cc: Andrew Cooper <andrew.cooper3@citrix.com>
> Cc: Keir Fraser <keir@xen.org>

Reviewed-by: Juergen Gross <jgross@suse.com>

> ---
>   xen/common/cpupool.c |   15 +++++++++++----
>   1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/xen/common/cpupool.c b/xen/common/cpupool.c
> index a947c24..cabaccd 100644
> --- a/xen/common/cpupool.c
> +++ b/xen/common/cpupool.c
> @@ -458,8 +458,10 @@ void cpupool_rm_domain(struct domain *d)
>    * unless we are resuming from S3, in which case we put the cpu back
>    * in the cpupool it was in prior to suspend.
>    */
> -static void cpupool_cpu_add(unsigned int cpu)
> +static int cpupool_cpu_add(unsigned int cpu)
>   {
> +    int ret = -EINVAL;
> +
>       spin_lock(&cpupool_lock);
>       cpumask_clear_cpu(cpu, &cpupool_locked_cpus);
>       cpumask_set_cpu(cpu, &cpupool_free_cpus);
> @@ -472,15 +474,20 @@ static void cpupool_cpu_add(unsigned int cpu)
>           {
>               if ( cpumask_test_cpu(cpu, (*c)->cpu_suspended ) )
>               {
> -                cpupool_assign_cpu_locked(*c, cpu);
> +                ret = cpupool_assign_cpu_locked(*c, cpu);
> +                if ( ret )
> +                    goto out;
>                   cpumask_clear_cpu(cpu, (*c)->cpu_suspended);
>               }
>           }
>       }
>
>       if ( cpumask_test_cpu(cpu, &cpupool_free_cpus) )
> -        cpupool_assign_cpu_locked(cpupool0, cpu);
> +        ret = cpupool_assign_cpu_locked(cpupool0, cpu);
> + out:
>       spin_unlock(&cpupool_lock);
> +
> +    return ret;
>   }
>
>   /*
> @@ -715,7 +722,7 @@ static int cpu_callback(
>       {
>       case CPU_DOWN_FAILED:
>       case CPU_ONLINE:
> -        cpupool_cpu_add(cpu);
> +        rc = cpupool_cpu_add(cpu);
>           break;
>       case CPU_DOWN_PREPARE:
>           rc = cpupool_cpu_remove(cpu);
>
>