Re: [Xen-devel] [PATCH 2/6] common/gnttab: Correct __acquire_grant_for_copy() fastpath for transitive grants

>>> On 15.08.17 at 14:30, wrote: > --- a/xen/common/grant_table.c > +++ b/xen/common/grant_table.c > @@ -2345,6 +2345,12 @@ __acquire_grant_for_copy( > * non-zero refcount and hence a valid owner. > */ > ASSERT(td); > + > +if ( td !=

[Xen-devel] [PATCH 2/6] common/gnttab: Correct __acquire_grant_for_copy() fastpath for transitive grants

An RCU reference is always dropped for the transitive grant in __release_grant_for_copy(). The __acquire fastpath needs to match the slowpath in terms of number of references taken. This is only not an XSA by luck. rcu_unlock_domain() is a nop other than decrementing the preempt count, and