diff options
Diffstat (limited to 'system/xen/patches/xsa155-xen-0002-blktap2-Use-RING_COPY_REQUEST.patch')
| -rw-r--r-- | system/xen/patches/xsa155-xen-0002-blktap2-Use-RING_COPY_REQUEST.patch | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/system/xen/patches/xsa155-xen-0002-blktap2-Use-RING_COPY_REQUEST.patch b/system/xen/patches/xsa155-xen-0002-blktap2-Use-RING_COPY_REQUEST.patch new file mode 100644 index 0000000000..2d80a7bd43 --- /dev/null +++ b/system/xen/patches/xsa155-xen-0002-blktap2-Use-RING_COPY_REQUEST.patch @@ -0,0 +1,75 @@ +From 851ffb4eea917e2708c912291dea4d133026c0ac Mon Sep 17 00:00:00 2001 +From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> +Date: Fri, 20 Nov 2015 12:16:02 -0500 +Subject: [PATCH 2/3] blktap2: Use RING_COPY_REQUEST + +Instead of RING_GET_REQUEST. Using a local copy of the +ring (and also with proper memory barriers) will mean +we can do not have to worry about the compiler optimizing +the code and doing a double-fetch in the shared memory space. + +This is part of XSA155. + +Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> + +--- +v2: Fix compile issues with tapdisk-vbd +--- + tools/blktap2/drivers/block-log.c | 3 ++- + tools/blktap2/drivers/tapdisk-vbd.c | 8 ++++---- + 2 files changed, 6 insertions(+), 5 deletions(-) + +diff --git a/tools/blktap2/drivers/block-log.c b/tools/blktap2/drivers/block-log.c +index 5330cdc..5f3bd35 100644 +--- a/tools/blktap2/drivers/block-log.c ++++ b/tools/blktap2/drivers/block-log.c +@@ -494,11 +494,12 @@ static int ctl_kick(struct tdlog_state* s, int fd) + reqstart = s->bring.req_cons; + reqend = s->sring->req_prod; + ++ xen_mb(); + BDPRINTF("ctl: ring kicked (start = %u, end = %u)", reqstart, reqend); + + while (reqstart != reqend) { + /* XXX actually submit these! */ +- memcpy(&req, RING_GET_REQUEST(&s->bring, reqstart), sizeof(req)); ++ RING_COPY_REQUEST(&s->bring, reqstart, &req); + BDPRINTF("ctl: read request %"PRIu64":%u", req.sector, req.count); + s->bring.req_cons = ++reqstart; + +diff --git a/tools/blktap2/drivers/tapdisk-vbd.c b/tools/blktap2/drivers/tapdisk-vbd.c +index 6d1d94a..89ef9ed 100644 +--- a/tools/blktap2/drivers/tapdisk-vbd.c ++++ b/tools/blktap2/drivers/tapdisk-vbd.c +@@ -1555,7 +1555,7 @@ tapdisk_vbd_pull_ring_requests(td_vbd_t *vbd) + int idx; + RING_IDX rp, rc; + td_ring_t *ring; +- blkif_request_t *req; ++ blkif_request_t req; + td_vbd_request_t *vreq; + + ring = &vbd->ring; +@@ -1566,16 +1566,16 @@ tapdisk_vbd_pull_ring_requests(td_vbd_t *vbd) + xen_rmb(); + + for (rc = ring->fe_ring.req_cons; rc != rp; rc++) { +- req = RING_GET_REQUEST(&ring->fe_ring, rc); ++ RING_COPY_REQUEST(&ring->fe_ring, rc, &req); + ++ring->fe_ring.req_cons; + +- idx = req->id; ++ idx = req.id; + vreq = &vbd->request_list[idx]; + + ASSERT(list_empty(&vreq->next)); + ASSERT(vreq->secs_pending == 0); + +- memcpy(&vreq->req, req, sizeof(blkif_request_t)); ++ memcpy(&vreq->req, &req, sizeof(blkif_request_t)); + vbd->received++; + vreq->vbd = vbd; + +-- +2.1.4 + |