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dataplane: Fix startup race.

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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 <cornelia.huck@de.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Cornelia Huck 2013-09-04 14:16:15 +02:00 committed by Stefan Hajnoczi
parent 5daa74a6eb
commit 8caf907f07
1 changed files with 9 additions and 0 deletions
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9
hw/block/dataplane/virtio-blk.c
View File

@ -42,6 +42,7 @@ typedef struct {
struct VirtIOBlockDataPlane { struct VirtIOBlockDataPlane {
bool started; bool started;
bool starting;
bool stopping; bool stopping;
QEMUBH *start_bh; QEMUBH *start_bh;
QemuThread thread; QemuThread thread;
@ -451,8 +452,15 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
return; return;
} }
if (s->starting) {
return;
}
s->starting = true;
vq = virtio_get_queue(s->vdev, 0); vq = virtio_get_queue(s->vdev, 0);
if (!vring_setup(&s->vring, s->vdev, 0)) { if (!vring_setup(&s->vring, s->vdev, 0)) {
s->starting = false;
return; return;
} }
@ -482,6 +490,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
s->io_notifier = *ioq_get_notifier(&s->ioqueue); s->io_notifier = *ioq_get_notifier(&s->ioqueue);
aio_set_event_notifier(s->ctx, &s->io_notifier, handle_io); aio_set_event_notifier(s->ctx, &s->io_notifier, handle_io);
s->starting = false;
s->started = true; s->started = true;
trace_virtio_blk_data_plane_start(s); trace_virtio_blk_data_plane_start(s);