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[Qemu-devel] [PATCH v2 2/2] xen: dont try setting max grants multiple ti
From: |
Juergen Gross |
Subject: |
[Qemu-devel] [PATCH v2 2/2] xen: dont try setting max grants multiple times |
Date: |
Fri, 22 Sep 2017 14:07:25 +0200 |
Trying to call xengnttab_set_max_grants() with the same file handle
might fail on some kernels, as this operation is allowed only once.
This is a problem for the qdisk backend as blk_connect() can be
called multiple times for a domain, e.g. in case grub-xen is being
used to boot it.
So instead of letting the generic backend code open the gnttab device
do it in blk_connect() and close it again in blk_disconnect.
Signed-off-by: Juergen Gross <address@hidden>
---
V2:
- always call blk_disconnect() from blk_free() in order to have the
gnttab device node closed (Anthony Perard)
---
hw/block/xen_disk.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c
index 62506e3167..e431bd89e8 100644
--- a/hw/block/xen_disk.c
+++ b/hw/block/xen_disk.c
@@ -1220,6 +1220,12 @@ static int blk_connect(struct XenDevice *xendev)
/* Add on the number needed for the ring pages */
max_grants += blkdev->nr_ring_ref;
+ blkdev->xendev.gnttabdev = xengnttab_open(NULL, 0);
+ if (blkdev->xendev.gnttabdev == NULL) {
+ xen_pv_printf(xendev, 0, "xengnttab_open failed: %s\n",
+ strerror(errno));
+ return -1;
+ }
if (xengnttab_set_max_grants(blkdev->xendev.gnttabdev, max_grants)) {
xen_pv_printf(xendev, 0, "xengnttab_set_max_grants failed: %s\n",
strerror(errno));
@@ -1327,6 +1333,11 @@ static void blk_disconnect(struct XenDevice *xendev)
}
blkdev->feature_persistent = false;
}
+
+ if (blkdev->xendev.gnttabdev) {
+ xengnttab_close(blkdev->xendev.gnttabdev);
+ blkdev->xendev.gnttabdev = NULL;
+ }
}
static int blk_free(struct XenDevice *xendev)
@@ -1334,9 +1345,7 @@ static int blk_free(struct XenDevice *xendev)
struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
struct ioreq *ioreq;
- if (blkdev->blk || blkdev->sring) {
- blk_disconnect(xendev);
- }
+ blk_disconnect(xendev);
while (!QLIST_EMPTY(&blkdev->freelist)) {
ioreq = QLIST_FIRST(&blkdev->freelist);
@@ -1363,7 +1372,6 @@ static void blk_event(struct XenDevice *xendev)
struct XenDevOps xen_blkdev_ops = {
.size = sizeof(struct XenBlkDev),
- .flags = DEVOPS_FLAG_NEED_GNTDEV,
.alloc = blk_alloc,
.init = blk_init,
.initialise = blk_connect,
--
2.12.3