Mailing List Archive

# HG changeset patch
# User kaf24@firebug.cl.cam.ac.uk
# Node ID 8754277cec01d26b7174a3ef8644ef557f42ed26
# Parent 4c588e255c8595f0502a56555a68379f8fcb034d
Fix blkback request notification holdoff. req_cons must be
updated before make_response() is called. This fixes attaching
ramdisk-backed vbds to a blkfront.

Signed-off-by: Keir Fraser <keir@xensource.com>

diff -r 4c588e255c85 -r 8754277cec01 linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c
--- a/linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c Sat Dec 3 10:00:03 2005
+++ b/linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c Sat Dec 3 10:41:49 2005
@@ -296,22 +296,23 @@
{
blkif_back_ring_t *blk_ring = &blkif->blk_ring;
blkif_request_t *req;
- RING_IDX i, rp;
+ RING_IDX rc, rp;
int more_to_do = 0;

+ rc = blk_ring->req_cons;
rp = blk_ring->sring->req_prod;
rmb(); /* Ensure we see queued requests up to 'rp'. */

- for (i = blk_ring->req_cons;
- (i != rp) && !RING_REQUEST_CONS_OVERFLOW(blk_ring, i);
- i++) {
+ while ((rc != rp) && !RING_REQUEST_CONS_OVERFLOW(blk_ring, rc)) {
if ((max_to_do-- == 0) ||
(NR_PENDING_REQS == MAX_PENDING_REQS)) {
more_to_do = 1;
break;
}
-
- req = RING_GET_REQUEST(blk_ring, i);
+
+ req = RING_GET_REQUEST(blk_ring, rc);
+ blk_ring->req_cons = ++rc; /* before make_response() */
+
switch (req->operation) {
case BLKIF_OP_READ:
case BLKIF_OP_WRITE:
@@ -327,7 +328,6 @@
}
}

- blk_ring->req_cons = i;
return more_to_do;
}


_______________________________________________
Xen-changelog mailing list
Xen-changelog@lists.xensource.com
http://lists.xensource.com/xen-changelog