code question?

[Jerone Young <jyoung5@us.ibm.com>]

Doing some janitorial (you cleaning the flooded toilets and such) work
today. I have come across this line of code that really I'm not sure
what the intent was..in xen/include/sched.h

#define hypercall_preempt_check() (unlikely(            \
        softirq_pending(smp_processor_id()) |           \
        (!!current->vcpu_info->evtchn_upcall_pending &  \
          !current->vcpu_info->evtchn_upcall_mask)      \
    ))

the part where we have !!current->vcpu_info_evtchen_upcall pending
should this be..should the "!! just be "!"?

And if so shouldn't this just be changed to 

#define hypercall_preempt_check() (unlikely( \
	softirq_pending(smp_processor_id()) |           \
	(!(current->vcpu_info->evtchn_upcall_pending & \
	  current->vcpu_info->evtchn_upcall_mask)) \
	))
	

In a lot of the code in Xen we are using the "!" operator with bitwise
operations..this is one of those examples.



-- 
Jerone Young
IBM Linux Technology Center
jyoung5@us.ibm.com
512-838-1157 (T/L: 678-1157)