Re: [Qemu-block] [PATCH] throttle-groups: fix restart coroutine iothread race

[Alberto Garcia]

On Wed 09 Jan 2019 12:01:44 PM CET, Stefan Hajnoczi wrote:
> The following QMP command leads to a crash when iothreads are used:
>
>   { 'execute': 'device_del', 'arguments': {'id': 'data'} }

I was trying to reproduce this and I found this crashing in master:

$ qemu-system-x86_64 -enable-kvm -qmp stdio -display none
{ "execute": "qmp_capabilities" }
{ "execute": "blockdev-add", "arguments": {"driver": "qcow2", "file": 
{"driver": "file", "filename": "hd.qcow2"}, "node-name": "hd0"}}
{ "execute": "object-add", "arguments": {"qom-type": "iothread", "id": 
"iothread0"}}
{ "execute": "x-blockdev-set-iothread", "arguments": {"node-name": "hd0", 
"iothread": "iothread0"}}
{ "execute": "device_add", "arguments": {"id": "virtio0", "driver": 
"virtio-blk-pci", "drive": "hd0"}}

Thread 1 "qemu-system-x86" received signal SIGABRT, Aborted.
__GI_raise (address@hidden) at ../sysdeps/unix/sysv/linux/raise.c:51
51         ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) bt
#0  __GI_raise (address@hidden) at ../sysdeps/unix/sysv/linux/raise.c:51
#1  [...] in __GI_abort () at abort.c:89
#2  [...] in error_exit () at util/qemu-thread-posix.c:36
#3  [...] in qemu_mutex_unlock_impl () at util/qemu-thread-posix.c:96
#4  [...] in aio_context_release () at util/async.c:516
#5  [...] in blk_prw () at block/block-backend.c:1262
#6  [...] in blk_pread () at block/block-backend.c:1424
#7  [...] in blk_pread_unthrottled () at block/block-backend.c:1279
#8  [...] in guess_disk_lchs () at hw/block/hd-geometry.c:71
#9  [...] in hd_geometry_guess () at hw/block/hd-geometry.c:136
#10 [...] in blkconf_geometry () at hw/block/block.c:99
#11 [...] in virtio_blk_device_realize () at hw/block/virtio-blk.c:944
#12 [...] in virtio_device_realize () at hw/virtio/virtio.c:2538
[...]

Berto