diff mbox series

[5/8] virtio-blk: mark GLOBAL_STATE_CODE functions

Message ID 20220609143727.1151816-6-eesposit@redhat.com
State New
Headers show
Series virtio-blk: removal of AioContext lock | expand

Commit Message

Emanuele Giuseppe Esposito June 9, 2022, 2:37 p.m. UTC 
Just as done in the block API, mark functions in virtio-blk
that are always called in the main loop with BQL held.

We know such functions are GS because they all are callbacks
from virtio.c API that has already classified them as GS.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
 hw/block/dataplane/virtio-blk.c |  4 ++++
 hw/block/virtio-blk.c           | 29 +++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

Comments

Stefan Hajnoczi July 5, 2022, 2:27 p.m. UTC | #1 
On Thu, Jun 09, 2022 at 10:37:24AM -0400, Emanuele Giuseppe Esposito wrote:
> Just as done in the block API, mark functions in virtio-blk
> that are always called in the main loop with BQL held.
> 
> We know such functions are GS because they all are callbacks
> from virtio.c API that has already classified them as GS.
> 
> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
> ---
>  hw/block/dataplane/virtio-blk.c |  4 ++++
>  hw/block/virtio-blk.c           | 29 +++++++++++++++++++++++++++++
>  2 files changed, 33 insertions(+)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
diff mbox series

Patch

diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index 03e10a36a4..bda6b3e8de 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -89,6 +89,8 @@  bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 
+    GLOBAL_STATE_CODE();
+
     *dataplane = NULL;
 
     if (conf->iothread) {
@@ -140,6 +142,8 @@  void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
 {
     VirtIOBlock *vblk;
 
+    GLOBAL_STATE_CODE();
+
     if (!s) {
         return;
     }
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index 4e6421c35e..2eb0408f92 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -51,6 +51,8 @@  static const VirtIOFeature feature_sizes[] = {
 
 static void virtio_blk_set_config_size(VirtIOBlock *s, uint64_t host_features)
 {
+    GLOBAL_STATE_CODE();
+
     s->config_size = MAX(VIRTIO_BLK_CFG_SIZE,
         virtio_feature_get_config_size(feature_sizes, host_features));
 
@@ -865,6 +867,10 @@  void virtio_blk_restart_bh(void *opaque)
     virtio_blk_process_queued_requests(s, true);
 }
 
+/*
+ * Only called when VM is started or stopped in cpus.c.
+ * No iothread runs in parallel
+ */
 static void virtio_blk_dma_restart_cb(void *opaque, bool running,
                                       RunState state)
 {
@@ -872,6 +878,8 @@  static void virtio_blk_dma_restart_cb(void *opaque, bool running,
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
     VirtioBusState *bus = VIRTIO_BUS(qbus);
 
+    GLOBAL_STATE_CODE();
+
     if (!running) {
         return;
     }
@@ -894,8 +902,14 @@  static void virtio_blk_reset(VirtIODevice *vdev)
     AioContext *ctx;
     VirtIOBlockReq *req;
 
+    GLOBAL_STATE_CODE();
+
     ctx = blk_get_aio_context(s->blk);
     aio_context_acquire(ctx);
+    /*
+     * This drain together with ->stop_ioeventfd() in virtio_pci_reset()
+     * stops all Iothreads.
+     */
     blk_drain(s->blk);
 
     /* We drop queued requests after blk_drain() because blk_drain() itself can
@@ -1064,11 +1078,17 @@  static void virtio_blk_set_status(VirtIODevice *vdev, uint8_t status)
     }
 }
 
+/*
+ * VM is stopped while doing migration, so iothread has
+ * no requests to process.
+ */
 static void virtio_blk_save_device(VirtIODevice *vdev, QEMUFile *f)
 {
     VirtIOBlock *s = VIRTIO_BLK(vdev);
     VirtIOBlockReq *req = s->rq;
 
+    GLOBAL_STATE_CODE();
+
     while (req) {
         qemu_put_sbyte(f, 1);
 
@@ -1082,11 +1102,17 @@  static void virtio_blk_save_device(VirtIODevice *vdev, QEMUFile *f)
     qemu_put_sbyte(f, 0);
 }
 
+/*
+ * VM is stopped while doing migration, so iothread has
+ * no requests to process.
+ */
 static int virtio_blk_load_device(VirtIODevice *vdev, QEMUFile *f,
                                   int version_id)
 {
     VirtIOBlock *s = VIRTIO_BLK(vdev);
 
+    GLOBAL_STATE_CODE();
+
     while (qemu_get_sbyte(f)) {
         unsigned nvqs = s->conf.num_queues;
         unsigned vq_idx = 0;
@@ -1135,6 +1161,7 @@  static const BlockDevOps virtio_block_ops = {
     .resize_cb = virtio_blk_resize,
 };
 
+/* Iothread is not yet created */
 static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
@@ -1143,6 +1170,8 @@  static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
     Error *err = NULL;
     unsigned i;
 
+    GLOBAL_STATE_CODE();
+
     if (!conf->conf.blk) {
         error_setg(errp, "drive property not set");
         return;