Re: [PATCH v10 5/6] x86/ioreq server: Asynchronously reset outstanding p2m_ioreq_server entries.

[Yu Zhang <yu.c.zhang@linux.intel.com>]

On 4/3/2017 10:36 PM, Jan Beulich wrote:
> So this produces the same -EINVAL as the earlier check in context
> above. I think it would be nice if neither did - -EINUSE for the first
> (which we don't have, so -EOPNOTSUPP would seem the second
> bets option there) and -EBUSY for the second would seem more
> appropriate. If you agree, respective adjustments could be done
> while committing, if no other reason for a v11 arises.

Thanks Jan.
But my code shows both will return -EBUSY, instead of -EINVAL for the 
mapping requirement:
       /* Unmap ioreq server from p2m type by passing flags with 0. */
       if ( flags == 0 )
       {
/rc = -EINVAL;/
           if ( p2m->ioreq.server != s )
               goto out;

           p2m->ioreq.server = NULL;
           p2m->ioreq.flags = 0;
       }
       else
       {
/rc = -EBUSY;/
           if ( p2m->ioreq.server != NULL )
               goto out;

           /*
            * It is possible that an ioreq server has just been unmapped,
            * released the spin lock, with some p2m_ioreq_server entries
            * in p2m table remained. We shall refuse another ioreq server
            * mapping request in such case.
            */
           if ( read_atomic(&p2m->ioreq.entry_count) )
               goto out;

           p2m->ioreq.server = s;
           p2m->ioreq.flags = flags;
       }

Are you really wanna use -EOPNOTSUPP when p2m->ioreq.server is not NULL 
for the mapping code?

For the unmapping code, -EINVAL is used when the ioreq server to be 
unmapped is not the designated one.
But for this one, I am not sure which one is better: -EINVAL or -EBUSY?

Yu

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