Re: [Xen-devel] [PATCH] correct rcu_unlock_domain()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 20/04/17 14:48, Jan Beulich wrote:
> Match rcu_lock_domain(), and remove the slightly misleading comment:
> This isn't just the companion to rcu_lock_domain_by_id() (and that
> latter function indeed also keeps the domain locked, not the domain
> list).
>
> No functional change, as rcu_read_{,un}lock() ignore their arguments
> anyway.
>
> Reported-by: Jann Horn <jannh@xxxxxxxxxx>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, although I think
it is worth stating in the commit message that the only reason this
currently works is because rcu_read_unlock() is entirely empty.

>
> --- a/xen/include/xen/sched.h
> +++ b/xen/include/xen/sched.h
> @@ -584,11 +584,10 @@ int rcu_lock_remote_domain_by_id(domid_t
>   */
>  int rcu_lock_live_remote_domain_by_id(domid_t dom, struct domain **d);
>  
> -/* Finish a RCU critical region started by rcu_lock_domain_by_id(). */
>  static inline void rcu_unlock_domain(struct domain *d)
>  {
>      if ( d != current->domain )
> -        rcu_read_unlock(&domlist_read_lock);
> +        rcu_read_unlock(d);
>  }
>  
>  static inline struct domain *rcu_lock_domain(struct domain *d)
>
>
>


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