Re: [Xen-devel] [PATCH v2] xen/sched: fix onlining cpu with core scheduling active

[Jürgen Groß <jgross@xxxxxxxx>]

Ping?

On 10.03.20 10:06, Juergen Gross wrote:
> When onlining a cpu cpupool_cpu_add() checks whether all siblings of
> the new cpu are free in order to decide whether to add it to cpupool0.
> In case the added cpu is not the last sibling to be onlined this test
> is wrong as it only checks for all online siblings to be free. The
> test should include the check for the number of siblings having
> reached the scheduling granularity of cpupool0, too.
>
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> ---
> V2:
> - modify condition form >= to == (Jan Beulich)
> ---
>   xen/common/sched/cpupool.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/xen/common/sched/cpupool.c b/xen/common/sched/cpupool.c
> index 9f70c7ec17..d40345b585 100644
> --- a/xen/common/sched/cpupool.c
> +++ b/xen/common/sched/cpupool.c
> @@ -616,7 +616,8 @@ static int cpupool_cpu_add(unsigned int cpu)
>       get_sched_res(cpu)->cpupool = NULL;
>   
>       cpus = sched_get_opt_cpumask(cpupool0->gran, cpu);
> -    if ( cpumask_subset(cpus, &cpupool_free_cpus) )
> +    if ( cpumask_subset(cpus, &cpupool_free_cpus) &&
> +         cpumask_weight(cpus) == cpupool_get_granularity(cpupool0) )
>           ret = cpupool_assign_cpu_locked(cpupool0, cpu);
>   
>       rcu_read_unlock(&sched_res_rculock);