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[Qemu-devel] [PATCH RFC] dataplane: Fix startup race.
From: |
Cornelia Huck |
Subject: |
[Qemu-devel] [PATCH RFC] dataplane: Fix startup race. |
Date: |
Wed, 4 Sep 2013 14:16:15 +0200 |
Avoid trying to setup dataplane again if dataplane setup is already in
progress. This may happen if an eventfd is triggered during setup.
I saw this occasionally with an experimental s390 irqfd implementation:
virtio_blk_handle_output
-> virtio_blk_data_plane_start
-> virtio_ccw_set_host_notifier
...
-> virtio_queue_set_host_notifier_fd_handler
-> virtio_queue_host_notifier_read
-> virtio_queue_notify_vq
-> virtio_blk_handle_output
-> virtio_blk_data_plane_start
-> vring_setup
-> hostmem_init
-> memory_listener_register
-> BOOM
As virtio-ccw tries to follow what virtio-pci does, it might be triggerable
for other platforms as well.
Signed-off-by: Cornelia Huck <address@hidden>
---
hw/block/dataplane/virtio-blk.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index 5a96ccd..f2d7350 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -42,6 +42,7 @@ typedef struct {
struct VirtIOBlockDataPlane {
bool started;
+ bool starting;
bool stopping;
QEMUBH *start_bh;
QemuThread thread;
@@ -451,8 +452,15 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
return;
}
+ if (s->starting) {
+ return;
+ }
+
+ s->starting = true;
+
vq = virtio_get_queue(s->vdev, 0);
if (!vring_setup(&s->vring, s->vdev, 0)) {
+ s->starting = false;
return;
}
@@ -482,6 +490,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
s->io_notifier = *ioq_get_notifier(&s->ioqueue);
aio_set_event_notifier(s->ctx, &s->io_notifier, handle_io);
+ s->starting = false;
s->started = true;
trace_virtio_blk_data_plane_start(s);
--
1.8.3.4
- [Qemu-devel] [PATCH RFC] dataplane: Fix startup race.,
Cornelia Huck <=