Re: [Xen-devel] [PATCH] xen/sched: fix error path in cpupool_unassign_cpu_start()

[Jan Beulich <jbeulich@xxxxxxxx>]

On 03.03.2020 09:03, Juergen Gross wrote:
> In case moving away all domains from the cpu to be removed is failing
> in cpupool_unassign_cpu_start() the error path is missing to release
> sched_res_rculock.
> 
> The normal exit path is releasing domlist_read_lock instead (this is
> currently no problem as the reference to the specific rcu lock is not
> used by rcu_read_unlock()).
> 
> Reported-by: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
albeit preferably with ...

> --- a/xen/common/sched/cpupool.c
> +++ b/xen/common/sched/cpupool.c
> @@ -466,7 +466,7 @@ static int cpupool_unassign_cpu_start(struct cpupool *c, 
> unsigned int cpu)
>          }
>          rcu_read_unlock(&domlist_read_lock);
>          if ( ret )
> -            goto out;
> +            goto out_rcu;
>      }
>      cpupool_moving_cpu = cpu;
>      atomic_inc(&c->refcnt);
> @@ -474,7 +474,8 @@ static int cpupool_unassign_cpu_start(struct cpupool *c, 
> unsigned int cpu)
>      cpumask_andnot(c->cpu_valid, c->cpu_valid, cpus);
>      cpumask_and(c->res_valid, c->cpu_valid, &sched_res_mask);
>  
> -    rcu_read_unlock(&domlist_read_lock);
> +out_rcu:

... the label indented by at least one blank, at which point it
may make sense to also ...

> +    rcu_read_unlock(&sched_res_rculock);
>  out:

... correct this one.

Jan

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