Re: A bug of Monitor Chardev ?

[Markus Armbruster]

"Longpeng (Mike, Cloud Infrastructure Service Product Dept.)"
<longpeng2@huawei.com> writes:

> We find a race during QEMU starting, which would case the QEMU process 
> coredump.
>
> <main loop>                             |    <MON iothread>
>                                         |
> [1] create MON chardev                  |
> qemu_create_early_backends              |
>   chardev_init_func                     |
>                                         |
> [2] create MON iothread                 |
> qemu_create_late_backends               |
>   mon_init_func                         |
>       aio_bh_schedule-----------------------> monitor_qmp_setup_handlers_bh
> [3] enter main loog                     |    tcp_chr_update_read_handler
> (* A client come in, e.g. Libvirt *)    |      update_ioc_handlers
> tcp_chr_new_client                      |
>   update_ioc_handlers                   |
>                                         |
>     [4] create new hup_source           |
>         s->hup_source = *PTR1*          |
>           g_source_attach(s->hup_source)|
>                                         |        [5] remove_hup_source(*PTR1*)
>                                         |            (create new hup_source)
>                                         |             s->hup_source = *PTR2*
>         [6] g_source_attach_unlocked    |
>               *PTR1* is freed by [5]    |
>                       
> Do you have any suggestion to fix this bug ? Thanks!

Do we?  We talked, but I'm not sure we reached a conclusion.