lkml.org 
[lkml]   [2013]   [Jan]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [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



\
 
 \ /
  Last update: 2013-01-28 18:01    [W:0.079 / U:0.004 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site