On Mon, Sep 14, 2020 at 05:29:11PM +0000, Michael Kelley wrote:
> From: Andrea Parri <[email protected]> Sent: Tuesday, September 8, 2020 
> 12:54 AM
> > 
> > > > @@ -300,6 +303,22 @@ int hv_ringbuffer_write(struct vmbus_channel 
> > > > *channel,
> > > >                                                      
> > > > kv_list[i].iov_len);
> > > >         }
> > > >
> > > > +       /*
> > > > +        * Allocate the request ID after the data has been copied into 
> > > > the
> > > > +        * ring buffer.  Once this request ID is allocated, the 
> > > > completion
> > > > +        * path could find the data and free it.
> > > > +        */
> > > > +
> > > > +       if (desc->flags == VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED) 
> > > > {
> > > > +               rqst_id = vmbus_next_request_id(&channel->requestor, 
> > > > requestid);
> > > > +               if (rqst_id == VMBUS_RQST_ERROR) {
> > > > +                       pr_err("No request id available\n");
> > > > +                       return -EAGAIN;
> > > > +               }
> > > > +       }
> > > > +       desc = hv_get_ring_buffer(outring_info) + old_write;
> > > > +       desc->trans_id = (rqst_id == VMBUS_NO_RQSTOR) ? requestid : 
> > > > rqst_id;
> > > > +
> > >
> > > This is a nit, but the above would be clearer to me if written like this:
> > >
> > >   flags = desc->flags;
> > >   if (flags == VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED) {
> > >           rqst_id = vmbus_next_request_id(&channel->requestor, requestid);
> > >           if (rqst_id == VMBUS_RQST_ERROR) {
> > >                   pr_err("No request id available\n");
> > >                   return -EAGAIN;
> > >           }
> > >   } else {
> > >           rqst_id = requestid;
> > >   }
> > >   desc = hv_get_ring_buffer(outring_info) + old_write;
> > >   desc->trans_id = rqst_id;
> > >
> > > The value of the flags field controls what will be used as the value for 
> > > the
> > > rqst_id.  Having another test to see which value will be used as the 
> > > trans_id
> > > somehow feels a bit redundant.  And then rqst_id doesn't have to be 
> > > initialized.
> > 
> > Agreed, will apply in the next version.
> > 
> 
> In an offline conversation, Andrea has pointed out that my proposed changes
> don't work.  After a second look, I'll agreed that Andrea's code is the best 
> that
> can be done, so my comments can be ignored.

Thanks for the confirmation, Michael.  So, I plan to keep this patch as
is for the next submission of the series (to be submitted shortly...).

Thanks,
  Andrea

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