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virtio-blk: add lock to protect s->rq
s->rq is accessed from IO_CODE and GLOBAL_STATE_CODE. Introduce a lock to protect s->rq and eliminate reliance on the AioContext lock. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Message-ID: <20230914140101.1065008-3-stefanha@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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@ -82,8 +82,11 @@ static int virtio_blk_handle_rw_error(VirtIOBlockReq *req, int error,
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/* Break the link as the next request is going to be parsed from the
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* ring again. Otherwise we may end up doing a double completion! */
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req->mr_next = NULL;
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req->next = s->rq;
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s->rq = req;
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WITH_QEMU_LOCK_GUARD(&s->rq_lock) {
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req->next = s->rq;
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s->rq = req;
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}
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} else if (action == BLOCK_ERROR_ACTION_REPORT) {
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virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
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if (acct_failed) {
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@ -1183,10 +1186,13 @@ static void virtio_blk_dma_restart_bh(void *opaque)
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{
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VirtIOBlock *s = opaque;
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VirtIOBlockReq *req = s->rq;
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VirtIOBlockReq *req;
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MultiReqBuffer mrb = {};
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s->rq = NULL;
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WITH_QEMU_LOCK_GUARD(&s->rq_lock) {
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req = s->rq;
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s->rq = NULL;
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}
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aio_context_acquire(blk_get_aio_context(s->conf.conf.blk));
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while (req) {
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@ -1238,22 +1244,29 @@ static void virtio_blk_reset(VirtIODevice *vdev)
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AioContext *ctx;
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VirtIOBlockReq *req;
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/* Dataplane has stopped... */
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assert(!s->dataplane_started);
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/* ...but requests may still be in flight. */
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ctx = blk_get_aio_context(s->blk);
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aio_context_acquire(ctx);
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blk_drain(s->blk);
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aio_context_release(ctx);
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/* We drop queued requests after blk_drain() because blk_drain() itself can
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* produce them. */
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while (s->rq) {
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req = s->rq;
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s->rq = req->next;
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virtqueue_detach_element(req->vq, &req->elem, 0);
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virtio_blk_free_request(req);
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WITH_QEMU_LOCK_GUARD(&s->rq_lock) {
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while (s->rq) {
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req = s->rq;
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s->rq = req->next;
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/* No other threads can access req->vq here */
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virtqueue_detach_element(req->vq, &req->elem, 0);
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virtio_blk_free_request(req);
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}
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}
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aio_context_release(ctx);
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assert(!s->dataplane_started);
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blk_set_enable_write_cache(s->blk, s->original_wce);
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}
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@ -1443,18 +1456,22 @@ static void virtio_blk_set_status(VirtIODevice *vdev, uint8_t status)
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static void virtio_blk_save_device(VirtIODevice *vdev, QEMUFile *f)
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{
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VirtIOBlock *s = VIRTIO_BLK(vdev);
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VirtIOBlockReq *req = s->rq;
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while (req) {
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qemu_put_sbyte(f, 1);
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WITH_QEMU_LOCK_GUARD(&s->rq_lock) {
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VirtIOBlockReq *req = s->rq;
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if (s->conf.num_queues > 1) {
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qemu_put_be32(f, virtio_get_queue_index(req->vq));
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while (req) {
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qemu_put_sbyte(f, 1);
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if (s->conf.num_queues > 1) {
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qemu_put_be32(f, virtio_get_queue_index(req->vq));
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}
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qemu_put_virtqueue_element(vdev, f, &req->elem);
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req = req->next;
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}
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qemu_put_virtqueue_element(vdev, f, &req->elem);
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req = req->next;
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}
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qemu_put_sbyte(f, 0);
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}
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@ -1480,8 +1497,11 @@ static int virtio_blk_load_device(VirtIODevice *vdev, QEMUFile *f,
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req = qemu_get_virtqueue_element(vdev, f, sizeof(VirtIOBlockReq));
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virtio_blk_init_request(s, virtio_get_queue(vdev, vq_idx), req);
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req->next = s->rq;
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s->rq = req;
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WITH_QEMU_LOCK_GUARD(&s->rq_lock) {
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req->next = s->rq;
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s->rq = req;
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}
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}
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return 0;
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@ -1628,6 +1648,8 @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
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s->host_features);
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virtio_init(vdev, VIRTIO_ID_BLOCK, s->config_size);
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qemu_mutex_init(&s->rq_lock);
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s->blk = conf->conf.blk;
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s->rq = NULL;
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s->sector_mask = (s->conf.conf.logical_block_size / BDRV_SECTOR_SIZE) - 1;
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@ -1679,6 +1701,7 @@ static void virtio_blk_device_unrealize(DeviceState *dev)
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virtio_del_queue(vdev, i);
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}
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qemu_coroutine_dec_pool_size(conf->num_queues * conf->queue_size / 2);
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qemu_mutex_destroy(&s->rq_lock);
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blk_ram_registrar_destroy(&s->blk_ram_registrar);
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qemu_del_vm_change_state_handler(s->change);
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blockdev_mark_auto_del(s->blk);
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@ -54,7 +54,8 @@ struct VirtIOBlockReq;
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struct VirtIOBlock {
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VirtIODevice parent_obj;
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BlockBackend *blk;
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void *rq;
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QemuMutex rq_lock;
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void *rq; /* protected by rq_lock */
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VirtIOBlkConf conf;
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unsigned short sector_mask;
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bool original_wce;
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