Done with this Coccinelle semantic patch @@ expression FMT, E1, E2; expression list ARGS; @@ - error_setg(E1, FMT, ARGS, error_get_pretty(E2)); + error_propagate(E1, E2);/*###*/ + error_prepend(E1, FMT/*@@@*/, ARGS); followed by manual cleanup, first because I can't figure out how to make Coccinelle transform strings, and second to get rid of now superfluous error_propagate(). We now use or propagate the original error whole instead of just its message obtained with error_get_pretty(). This avoids suppressing its hint (see commit50b7b00
), but I can't see how the errors touched in this commit could come with hints. It also improves the message printed with &error_abort when we screw up (see commit1e9b65b
). Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
328 lines
10 KiB
C
328 lines
10 KiB
C
/*
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* Dedicated thread for virtio-blk I/O processing
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*
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* Copyright 2012 IBM, Corp.
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* Copyright 2012 Red Hat, Inc. and/or its affiliates
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*
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* Authors:
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* Stefan Hajnoczi <stefanha@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*
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*/
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#include "trace.h"
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#include "qemu/iov.h"
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#include "qemu/thread.h"
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#include "qemu/error-report.h"
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#include "hw/virtio/virtio-access.h"
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#include "hw/virtio/dataplane/vring.h"
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#include "hw/virtio/dataplane/vring-accessors.h"
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#include "sysemu/block-backend.h"
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#include "hw/virtio/virtio-blk.h"
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#include "virtio-blk.h"
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#include "block/aio.h"
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#include "hw/virtio/virtio-bus.h"
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#include "qom/object_interfaces.h"
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struct VirtIOBlockDataPlane {
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bool started;
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bool starting;
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bool stopping;
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bool disabled;
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VirtIOBlkConf *conf;
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VirtIODevice *vdev;
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Vring vring; /* virtqueue vring */
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EventNotifier *guest_notifier; /* irq */
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QEMUBH *bh; /* bh for guest notification */
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/* Note that these EventNotifiers are assigned by value. This is
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* fine as long as you do not call event_notifier_cleanup on them
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* (because you don't own the file descriptor or handle; you just
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* use it).
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*/
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IOThread *iothread;
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AioContext *ctx;
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EventNotifier host_notifier; /* doorbell */
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/* Operation blocker on BDS */
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Error *blocker;
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void (*saved_complete_request)(struct VirtIOBlockReq *req,
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unsigned char status);
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};
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/* Raise an interrupt to signal guest, if necessary */
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static void notify_guest(VirtIOBlockDataPlane *s)
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{
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if (!vring_should_notify(s->vdev, &s->vring)) {
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return;
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}
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event_notifier_set(s->guest_notifier);
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}
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static void notify_guest_bh(void *opaque)
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{
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VirtIOBlockDataPlane *s = opaque;
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notify_guest(s);
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}
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static void complete_request_vring(VirtIOBlockReq *req, unsigned char status)
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{
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VirtIOBlockDataPlane *s = req->dev->dataplane;
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stb_p(&req->in->status, status);
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vring_push(s->vdev, &req->dev->dataplane->vring, &req->elem, req->in_len);
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/* Suppress notification to guest by BH and its scheduled
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* flag because requests are completed as a batch after io
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* plug & unplug is introduced, and the BH can still be
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* executed in dataplane aio context even after it is
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* stopped, so needn't worry about notification loss with BH.
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*/
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qemu_bh_schedule(s->bh);
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}
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static void handle_notify(EventNotifier *e)
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{
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VirtIOBlockDataPlane *s = container_of(e, VirtIOBlockDataPlane,
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host_notifier);
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VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
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event_notifier_test_and_clear(&s->host_notifier);
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blk_io_plug(s->conf->conf.blk);
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for (;;) {
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MultiReqBuffer mrb = {};
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int ret;
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/* Disable guest->host notifies to avoid unnecessary vmexits */
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vring_disable_notification(s->vdev, &s->vring);
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for (;;) {
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VirtIOBlockReq *req = virtio_blk_alloc_request(vblk);
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ret = vring_pop(s->vdev, &s->vring, &req->elem);
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if (ret < 0) {
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virtio_blk_free_request(req);
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break; /* no more requests */
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}
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trace_virtio_blk_data_plane_process_request(s, req->elem.out_num,
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req->elem.in_num,
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req->elem.index);
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virtio_blk_handle_request(req, &mrb);
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}
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if (mrb.num_reqs) {
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virtio_blk_submit_multireq(s->conf->conf.blk, &mrb);
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}
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if (likely(ret == -EAGAIN)) { /* vring emptied */
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/* Re-enable guest->host notifies and stop processing the vring.
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* But if the guest has snuck in more descriptors, keep processing.
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*/
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if (vring_enable_notification(s->vdev, &s->vring)) {
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break;
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}
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} else { /* fatal error */
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break;
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}
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}
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blk_io_unplug(s->conf->conf.blk);
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}
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/* Context: QEMU global mutex held */
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void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
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VirtIOBlockDataPlane **dataplane,
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Error **errp)
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{
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VirtIOBlockDataPlane *s;
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BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
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VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
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*dataplane = NULL;
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if (!conf->iothread) {
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return;
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}
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/* Don't try if transport does not support notifiers. */
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if (!k->set_guest_notifiers || !k->set_host_notifier) {
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error_setg(errp,
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"device is incompatible with dataplane "
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"(transport does not support notifiers)");
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return;
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}
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/* If dataplane is (re-)enabled while the guest is running there could be
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* block jobs that can conflict.
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*/
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if (blk_op_is_blocked(conf->conf.blk, BLOCK_OP_TYPE_DATAPLANE, errp)) {
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error_prepend(errp, "cannot start dataplane thread: ");
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return;
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}
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s = g_new0(VirtIOBlockDataPlane, 1);
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s->vdev = vdev;
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s->conf = conf;
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if (conf->iothread) {
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s->iothread = conf->iothread;
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object_ref(OBJECT(s->iothread));
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}
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s->ctx = iothread_get_aio_context(s->iothread);
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s->bh = aio_bh_new(s->ctx, notify_guest_bh, s);
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error_setg(&s->blocker, "block device is in use by data plane");
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blk_op_block_all(conf->conf.blk, s->blocker);
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blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_RESIZE, s->blocker);
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blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_DRIVE_DEL, s->blocker);
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blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_BACKUP_SOURCE, s->blocker);
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blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_CHANGE, s->blocker);
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blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_COMMIT_SOURCE, s->blocker);
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blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_COMMIT_TARGET, s->blocker);
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blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_EJECT, s->blocker);
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blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_EXTERNAL_SNAPSHOT, s->blocker);
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blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT, s->blocker);
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blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT_DELETE,
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s->blocker);
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blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_MIRROR_SOURCE, s->blocker);
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blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_STREAM, s->blocker);
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blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_REPLACE, s->blocker);
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*dataplane = s;
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}
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/* Context: QEMU global mutex held */
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void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
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{
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if (!s) {
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return;
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}
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virtio_blk_data_plane_stop(s);
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blk_op_unblock_all(s->conf->conf.blk, s->blocker);
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error_free(s->blocker);
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qemu_bh_delete(s->bh);
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object_unref(OBJECT(s->iothread));
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g_free(s);
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}
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/* Context: QEMU global mutex held */
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void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
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{
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BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
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VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
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VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
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VirtQueue *vq;
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int r;
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if (s->started || s->disabled) {
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return;
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}
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if (s->starting) {
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return;
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}
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s->starting = true;
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vq = virtio_get_queue(s->vdev, 0);
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if (!vring_setup(&s->vring, s->vdev, 0)) {
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goto fail_vring;
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}
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/* Set up guest notifier (irq) */
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r = k->set_guest_notifiers(qbus->parent, 1, true);
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if (r != 0) {
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fprintf(stderr, "virtio-blk failed to set guest notifier (%d), "
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"ensure -enable-kvm is set\n", r);
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goto fail_guest_notifiers;
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}
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s->guest_notifier = virtio_queue_get_guest_notifier(vq);
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/* Set up virtqueue notify */
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r = k->set_host_notifier(qbus->parent, 0, true);
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if (r != 0) {
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fprintf(stderr, "virtio-blk failed to set host notifier (%d)\n", r);
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goto fail_host_notifier;
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}
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s->host_notifier = *virtio_queue_get_host_notifier(vq);
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s->saved_complete_request = vblk->complete_request;
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vblk->complete_request = complete_request_vring;
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s->starting = false;
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s->started = true;
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trace_virtio_blk_data_plane_start(s);
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blk_set_aio_context(s->conf->conf.blk, s->ctx);
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/* Kick right away to begin processing requests already in vring */
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event_notifier_set(virtio_queue_get_host_notifier(vq));
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/* Get this show started by hooking up our callbacks */
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aio_context_acquire(s->ctx);
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aio_set_event_notifier(s->ctx, &s->host_notifier, true,
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handle_notify);
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aio_context_release(s->ctx);
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return;
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fail_host_notifier:
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k->set_guest_notifiers(qbus->parent, 1, false);
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fail_guest_notifiers:
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vring_teardown(&s->vring, s->vdev, 0);
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s->disabled = true;
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fail_vring:
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s->starting = false;
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}
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/* Context: QEMU global mutex held */
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void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
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{
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BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
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VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
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VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
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/* Better luck next time. */
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if (s->disabled) {
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s->disabled = false;
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return;
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}
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if (!s->started || s->stopping) {
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return;
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}
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s->stopping = true;
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vblk->complete_request = s->saved_complete_request;
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trace_virtio_blk_data_plane_stop(s);
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aio_context_acquire(s->ctx);
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/* Stop notifications for new requests from guest */
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aio_set_event_notifier(s->ctx, &s->host_notifier, true, NULL);
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/* Drain and switch bs back to the QEMU main loop */
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blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context());
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aio_context_release(s->ctx);
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/* Sync vring state back to virtqueue so that non-dataplane request
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* processing can continue when we disable the host notifier below.
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*/
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vring_teardown(&s->vring, s->vdev, 0);
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k->set_host_notifier(qbus->parent, 0, false);
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/* Clean up guest notifier (irq) */
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k->set_guest_notifiers(qbus->parent, 1, false);
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s->started = false;
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s->stopping = false;
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}
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