From a1abf40d6be2fc4b40d90ae3b46442f4a671776b Mon Sep 17 00:00:00 2001 From: Gonglei Date: Sat, 12 Jul 2014 11:43:37 +0800 Subject: [PATCH 1/3] linux-aio: Fix laio resource leak when hotplug virtio-scsi disks using laio, the aio_nr will increase in laio_init() by io_setup(), we can see the number by # cat /proc/sys/fs/aio-nr 128 if the aio_nr attach the maxnum, which found from # cat /proc/sys/fs/aio-max-nr 65536 the hotplug process will fail because of aio context leak. Fix it by io_destroy in laio_cleanup(). Reported-by: daifulai Signed-off-by: Gonglei Signed-off-by: Stefan Hajnoczi --- block/linux-aio.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/block/linux-aio.c b/block/linux-aio.c index 48673690ac..7ac7e8c99c 100644 --- a/block/linux-aio.c +++ b/block/linux-aio.c @@ -310,5 +310,10 @@ void laio_cleanup(void *s_) struct qemu_laio_state *s = s_; event_notifier_cleanup(&s->e); + + if (io_destroy(s->ctx) != 0) { + fprintf(stderr, "%s: destroy AIO context %p failed\n", + __func__, &s->ctx); + } g_free(s); } From e926d9b8c52d5ddf413617df4b341a3114642b14 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Sat, 12 Jul 2014 12:08:52 +0800 Subject: [PATCH 2/3] virtio-blk: data-plane: fix save/set .complete_request in start The callback has to be saved and reset in virtio_blk_data_plane_start(), otherwise dataplane's requests will be completed in qemu aio context. Reviewed-by: Fam Zheng Signed-off-by: Ming Lei Signed-off-by: Stefan Hajnoczi --- hw/block/dataplane/virtio-blk.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index 227bb15efc..e88862dc50 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -125,7 +125,6 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk, Error **errp) { VirtIOBlockDataPlane *s; - VirtIOBlock *vblk = VIRTIO_BLK(vdev); Error *local_err = NULL; BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev))); VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus); @@ -178,8 +177,6 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk, bdrv_op_block_all(blk->conf.bs, s->blocker); *dataplane = s; - s->saved_complete_request = vblk->complete_request; - vblk->complete_request = complete_request_vring; } /* Context: QEMU global mutex held */ @@ -201,6 +198,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s) { BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev))); VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus); + VirtIOBlock *vblk = VIRTIO_BLK(s->vdev); VirtQueue *vq; if (s->started) { @@ -234,6 +232,9 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s) } s->host_notifier = *virtio_queue_get_host_notifier(vq); + s->saved_complete_request = vblk->complete_request; + vblk->complete_request = complete_request_vring; + s->starting = false; s->started = true; trace_virtio_blk_data_plane_start(s); From 5b2ffbe4d99843fd8305c573a100047a8c962327 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Sat, 12 Jul 2014 12:08:53 +0800 Subject: [PATCH 3/3] virtio-blk: dataplane: notify guest as a batch Now requests are submitted as a batch, so it is natural to notify guest as a batch too. This may suppress interrupt notification to VM a lot: - in my test, decreased by ~13K/sec Signed-off-by: Ming Lei Signed-off-by: Stefan Hajnoczi --- hw/block/dataplane/virtio-blk.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index e88862dc50..d6ba65ca23 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -34,6 +34,7 @@ struct VirtIOBlockDataPlane { VirtIODevice *vdev; Vring vring; /* virtqueue vring */ EventNotifier *guest_notifier; /* irq */ + QEMUBH *bh; /* bh for guest notification */ /* Note that these EventNotifiers are assigned by value. This is * fine as long as you do not call event_notifier_cleanup on them @@ -61,13 +62,28 @@ static void notify_guest(VirtIOBlockDataPlane *s) event_notifier_set(s->guest_notifier); } +static void notify_guest_bh(void *opaque) +{ + VirtIOBlockDataPlane *s = opaque; + + notify_guest(s); +} + static void complete_request_vring(VirtIOBlockReq *req, unsigned char status) { + VirtIOBlockDataPlane *s = req->dev->dataplane; stb_p(&req->in->status, status); vring_push(&req->dev->dataplane->vring, &req->elem, req->qiov.size + sizeof(*req->in)); - notify_guest(req->dev->dataplane); + + /* Suppress notification to guest by BH and its scheduled + * flag because requests are completed as a batch after io + * plug & unplug is introduced, and the BH can still be + * executed in dataplane aio context even after it is + * stopped, so needn't worry about notification loss with BH. + */ + qemu_bh_schedule(s->bh); } static void handle_notify(EventNotifier *e) @@ -172,6 +188,7 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk, s->iothread = &s->internal_iothread_obj; } s->ctx = iothread_get_aio_context(s->iothread); + s->bh = aio_bh_new(s->ctx, notify_guest_bh, s); error_setg(&s->blocker, "block device is in use by data plane"); bdrv_op_block_all(blk->conf.bs, s->blocker); @@ -190,6 +207,7 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s) bdrv_op_unblock_all(s->blk->conf.bs, s->blocker); error_free(s->blocker); object_unref(OBJECT(s->iothread)); + qemu_bh_delete(s->bh); g_free(s); }