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virtio-scsi: dataplane: fail setup gracefully

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The dataplane code is currently doing a hard exit on various setup
failures. In practice, this may mean that a guest suddenly dies after
a dataplane device failed to come up (e.g., when a file descriptor
limit is hit for the nth device).

Let's just try to unwind the setup instead and return.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Cornelia Huck 2014-10-15 15:15:25 +02:00 committed by Paolo Bonzini
parent 6d2c83165b
commit 361dcc790d
1 changed files with 70 additions and 9 deletions
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79
hw/scsi/virtio-scsi-dataplane.c
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@ -53,7 +53,7 @@ static VirtIOSCSIVring *virtio_scsi_vring_init(VirtIOSCSI *s,
if (rc != 0) {
fprintf(stderr, "virtio-scsi: Failed to set host notifier (%d)\n",
rc);
exit(1);
return NULL;
}
r->host_notifier = *virtio_queue_get_host_notifier(vq);
r->guest_notifier = *virtio_queue_get_guest_notifier(vq);
@ -63,9 +63,15 @@ static VirtIOSCSIVring *virtio_scsi_vring_init(VirtIOSCSI *s,
if (!vring_setup(&r->vring, VIRTIO_DEVICE(s), n)) {
fprintf(stderr, "virtio-scsi: VRing setup failed\n");
exit(1);
goto fail_vring;
}
return r;
fail_vring:
aio_set_event_notifier(s->ctx, &r->host_notifier, NULL);
k->set_host_notifier(qbus->parent, n, false);
g_slice_free(VirtIOSCSIVring, r);
return NULL;
}
VirtIOSCSIReq *virtio_scsi_pop_req_vring(VirtIOSCSI *s,
@ -141,6 +147,46 @@ static void virtio_scsi_iothread_handle_cmd(EventNotifier *notifier)
}
}
/* assumes s->ctx held */
static void virtio_scsi_clear_aio(VirtIOSCSI *s)
{
VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
int i;
if (s->ctrl_vring) {
aio_set_event_notifier(s->ctx, &s->ctrl_vring->host_notifier, NULL);
}
if (s->event_vring) {
aio_set_event_notifier(s->ctx, &s->event_vring->host_notifier, NULL);
}
if (s->cmd_vrings) {
for (i = 0; i < vs->conf.num_queues && s->cmd_vrings[i]; i++) {
aio_set_event_notifier(s->ctx, &s->cmd_vrings[i]->host_notifier, NULL);
}
}
}
static void virtio_scsi_vring_teardown(VirtIOSCSI *s)
{
VirtIODevice *vdev = VIRTIO_DEVICE(s);
VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
int i;
if (s->ctrl_vring) {
vring_teardown(&s->ctrl_vring->vring, vdev, 0);
}
if (s->event_vring) {
vring_teardown(&s->event_vring->vring, vdev, 1);
}
if (s->cmd_vrings) {
for (i = 0; i < vs->conf.num_queues && s->cmd_vrings[i]; i++) {
vring_teardown(&s->cmd_vrings[i]->vring, vdev, 2 + i);
}
free(s->cmd_vrings);
s->cmd_vrings = NULL;
}
}
/* Context: QEMU global mutex held */
void virtio_scsi_dataplane_start(VirtIOSCSI *s)
{
@ -165,27 +211,47 @@ void virtio_scsi_dataplane_start(VirtIOSCSI *s)
if (rc != 0) {
fprintf(stderr, "virtio-scsi: Failed to set guest notifiers (%d), "
"ensure -enable-kvm is set\n", rc);
exit(1);
goto fail_guest_notifiers;
}
aio_context_acquire(s->ctx);
s->ctrl_vring = virtio_scsi_vring_init(s, vs->ctrl_vq,
virtio_scsi_iothread_handle_ctrl,
0);
if (!s->ctrl_vring) {
goto fail_vrings;
}
s->event_vring = virtio_scsi_vring_init(s, vs->event_vq,
virtio_scsi_iothread_handle_event,
1);
if (!s->event_vring) {
goto fail_vrings;
}
s->cmd_vrings = g_malloc0(sizeof(VirtIOSCSIVring) * vs->conf.num_queues);
for (i = 0; i < vs->conf.num_queues; i++) {
s->cmd_vrings[i] =
virtio_scsi_vring_init(s, vs->cmd_vqs[i],
virtio_scsi_iothread_handle_cmd,
i + 2);
if (!s->cmd_vrings[i]) {
goto fail_vrings;
}
}
aio_context_release(s->ctx);
s->dataplane_starting = false;
s->dataplane_started = true;
fail_vrings:
virtio_scsi_clear_aio(s);
aio_context_release(s->ctx);
virtio_scsi_vring_teardown(s);
for (i = 0; i < vs->conf.num_queues + 2; i++) {
k->set_host_notifier(qbus->parent, i, false);
}
k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
fail_guest_notifiers:
s->dataplane_starting = false;
}
/* Context: QEMU global mutex held */
@ -193,7 +259,6 @@ void virtio_scsi_dataplane_stop(VirtIOSCSI *s)
{
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
VirtIODevice *vdev = VIRTIO_DEVICE(s);
VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
int i;
@ -220,11 +285,7 @@ void virtio_scsi_dataplane_stop(VirtIOSCSI *s)
/* Sync vring state back to virtqueue so that non-dataplane request
* processing can continue when we disable the host notifier below.
*/
vring_teardown(&s->ctrl_vring->vring, vdev, 0);
vring_teardown(&s->event_vring->vring, vdev, 1);
for (i = 0; i < vs->conf.num_queues; i++) {
vring_teardown(&s->cmd_vrings[i]->vring, vdev, 2 + i);
}
virtio_scsi_vring_teardown(s);
for (i = 0; i < vs->conf.num_queues + 2; i++) {
k->set_host_notifier(qbus->parent, i, false);