Messages in this thread | | | Date | Fri, 25 Jan 2013 13:29:02 -0500 | From | Konrad Rzeszutek Wilk <> | Subject | Re: [Xen-devel] [PATCH 2/3] xen/ring: Add a new macro to detect whether there is an overflow in requests and response. |
| |
On Fri, Jan 25, 2013 at 06:45:29PM +0100, Roger Pau Monné wrote: > On 25/01/13 18:32, Konrad Rzeszutek Wilk wrote: > > We want to be able to exit if the difference between the request > > produced (what the frontend tells us) and the requests consumed > > (what we have so far processed) is greater than the ring size. > > > > If so, we should terminate the loop as the request produced > > is not trusted and it means it is bogus. > > > > Cc: stable@vger.kernel.org > > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > > --- > > include/xen/interface/io/ring.h | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/include/xen/interface/io/ring.h b/include/xen/interface/io/ring.h > > index 75271b9..1114dde 100644 > > --- a/include/xen/interface/io/ring.h > > +++ b/include/xen/interface/io/ring.h > > @@ -188,6 +188,12 @@ struct __name##_back_ring { \ > > #define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \ > > (((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r)) > > > > +/* Loop termination condition: Is the difference between request produced > > + * and request consumed greater than the ring size. If so, terminate the > > + * loop. */ > > +#define RING_REQUEST_PROD_OVERFLOW(_r, _cons, _prod) \ > > + (((_prod) - (_prod)) > RING_SIZE(_r)) > > Shouldn't the second _prod be _cons?
Yes :-) Was just testing everybody :-)
> > > + > > #define RING_PUSH_REQUESTS(_r) do { \ > > wmb(); /* back sees requests /before/ updated producer index */ \ > > (_r)->sring->req_prod = (_r)->req_prod_pvt; \ > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |