Messages in this thread | | | Date | Mon, 28 Jan 2013 16:18:59 +0000 | From | "Jan Beulich" <> | Subject | Re: [Xen-devel] [PATCH 3/3] xen/blkback: Check for insane amounts of request on the ring. |
| |
>>> On 28.01.13 at 16:42, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> wrote: > On Mon, Jan 28, 2013 at 11:07:46AM +0000, Jan Beulich wrote: >> >>> On 25.01.13 at 19:43, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> wrote: >> > @@ -764,6 +768,9 @@ __do_block_io_op(struct xen_blkif *blkif) >> > rp = blk_rings->common.sring->req_prod; >> > rmb(); /* Ensure we see queued requests up to 'rp'. */ >> > >> > + if (RING_REQUEST_PROD_OVERFLOW(&blk_rings->common, rp, rc)) >> > + return -EACCES; >> >> Actually I wonder whether we need the new macro at all: It seems >> to me that using RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rp) >> here would achieve the same effect. > > But it would not. The RING_REQUEST_CONS_OVERFLOW only check that the > non-shared ring entries (rsp_prod and rsp_prod_pvt) are less than > the size of the ring (32). In other words - they check whether we want > to process more requests as we still have a back-log of responses to > deal with.
So did you not notice that here 'rp' (i.e. req_prod) is being passed, not 'rc'?
Jan
| |