[PATCH] x86/mm: replace bogus assertion in paging_log_dirty_op()

[Jan Beulich]

While I was the one to introduce it, I don't think it is correct: A
bogus continuation call issued by a tool stack domain may find another
continuation in progress. IOW we've been asserting caller controlled
state (which is reachable only via a domctl), and the early (lock-less)
check in paging_domctl() helps in a limited way only.

Signed-off-by: Jan Beulich <jbeul...@suse.com>

--- a/xen/arch/x86/mm/paging.c
+++ b/xen/arch/x86/mm/paging.c
@@ -431,8 +431,8 @@ static int paging_log_dirty_op(struct do
               d->arch.paging.preempt.op != sc->op )
     {
         paging_unlock(d);
-        ASSERT(!resuming);
-        domain_unpause(d);
+        if ( !resuming )
+            domain_unpause(d);
         return -EBUSY;
     }