Re: [Xen-devel] xenconsole: Define and use a macro INVALID_XEN_PFN instead of -1

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Oct 18, 2017 at 04:02:45AM -0600, Jan Beulich wrote:
> >>> On 17.10.17 at 18:46, <bhupinder.thakur@xxxxxxxxxx> wrote:
> > --- a/tools/console/daemon/io.c
> > +++ b/tools/console/daemon/io.c
> > @@ -658,12 +658,12 @@ static void console_unmap_interface(struct console 
> > *con)
> >  {
> >     if (con->interface == NULL)
> >             return;
> > -   if (xgt_handle && con->ring_ref == -1)
> > +   if (xgt_handle && con->ring_ref == INVALID_XEN_PFN)
> >             xengnttab_unmap(xgt_handle, con->interface, 1);
> >     else
> >             munmap(con->interface, XC_PAGE_SIZE);
> >     con->interface = NULL;
> > -   con->ring_ref = -1;
> > +   con->ring_ref = INVALID_XEN_PFN;
> >  }
> >   
> >  static int console_create_ring(struct console *con)
> > @@ -698,7 +698,7 @@ static int console_create_ring(struct console *con)
> >     free(type);
> >  
> >     /* If using ring_ref and it has changed, remap */
> > -   if (ring_ref != con->ring_ref && con->ring_ref != -1)
> > +   if (ring_ref != con->ring_ref && con->ring_ref != INVALID_XEN_PFN)
> >             console_unmap_interface(con);
> >  
> >     if (!con->interface && xgt_handle && con->use_gnttab) {
> > @@ -706,7 +706,7 @@ static int console_create_ring(struct console *con)
> >             con->interface = xengnttab_map_grant_ref(xgt_handle,
> >                     dom->domid, GNTTAB_RESERVED_CONSOLE,
> >                     PROT_READ|PROT_WRITE);
> > -           con->ring_ref = -1;
> > +           con->ring_ref = INVALID_XEN_PFN;
> >     }
> >     if (!con->interface) {
> >             /* Fall back to xc_map_foreign_range */
> > @@ -812,7 +812,7 @@ static int console_init(struct console *con, struct 
> > domain *dom, void **data)
> >     con->master_pollfd_idx = -1;
> >     con->slave_fd = -1;
> >     con->log_fd = -1;
> > -   con->ring_ref = -1;
> > +   con->ring_ref = INVALID_XEN_PFN;
> >     con->local_port = -1;
> >     con->remote_port = -1;
> >     con->xce_pollfd_idx = -1;
> > --- a/xen/include/public/xen.h
> > +++ b/xen/include/public/xen.h
> > @@ -37,6 +37,8 @@
> >  #error "Unsupported architecture"
> >  #endif
> >  
> > +#define INVALID_XEN_PFN (~(xen_pfn_t)0)
> 
> As said before, the uses of this which you introduce don't warrant
> this addition to the public interface (which, if it was added, also
> should start with XEN_). I'm not going to NAK such a (corrected)
> addition to the public interface, but given the users I'm also not
> going to ACK it (but perhaps another REST maintainer would).
> 

I agree with you here. We don't need this in public interface yet.

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