diff options
| author | Sergio Lopez <slp@redhat.com> | 2019-09-16 13:24:12 +0200 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2019-10-08 14:28:25 +0100 |
| commit | 9b92fbcf45ed6ed1daceba8480b0d9e8a327b5ce (patch) | |
| tree | b1789ad658e461960ad9b8774985a759e236a935 /hw/block | |
| parent | d38d6de2a1fe209c849e8392f99e214d0a2db319 (diff) | |
virtio-blk: schedule virtio_notify_config to run on main context
virtio_notify_config() needs to acquire the global mutex, which isn't
allowed from an iothread, and may lead to a deadlock like this:
- main thead
* Has acquired: qemu_global_mutex.
* Is trying the acquire: iothread AioContext lock via
AIO_WAIT_WHILE (after aio_poll).
- iothread
* Has acquired: AioContext lock.
* Is trying to acquire: qemu_global_mutex (via
virtio_notify_config->prepare_mmio_access).
If virtio_blk_resize() is called from an iothread, schedule
virtio_notify_config() to be run in the main context BH.
[Removed unnecessary newline as suggested by Kevin Wolf
<kwolf@redhat.com>.
--Stefan]
Signed-off-by: Sergio Lopez <slp@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-id: 20190916112411.21636-1-slp@redhat.com
Message-Id: <20190916112411.21636-1-slp@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'hw/block')
| -rw-r--r-- | hw/block/virtio-blk.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index 18851601cb..ed2ddebd2b 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -16,6 +16,7 @@ #include "qemu/iov.h" #include "qemu/module.h" #include "qemu/error-report.h" +#include "qemu/main-loop.h" #include "trace.h" #include "hw/block/block.h" #include "hw/qdev-properties.h" @@ -1086,11 +1087,24 @@ static int virtio_blk_load_device(VirtIODevice *vdev, QEMUFile *f, return 0; } +static void virtio_resize_cb(void *opaque) +{ + VirtIODevice *vdev = opaque; + + assert(qemu_get_current_aio_context() == qemu_get_aio_context()); + virtio_notify_config(vdev); +} + static void virtio_blk_resize(void *opaque) { VirtIODevice *vdev = VIRTIO_DEVICE(opaque); - virtio_notify_config(vdev); + /* + * virtio_notify_config() needs to acquire the global mutex, + * so it can't be called from an iothread. Instead, schedule + * it to be run in the main context BH. + */ + aio_bh_schedule_oneshot(qemu_get_aio_context(), virtio_resize_cb, vdev); } static const BlockDevOps virtio_block_ops = { |