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

[Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx>]

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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