From: "Marc-André Lureau" <marcandre.lureau@gmail.com>
To: "Longpeng (Mike,
Cloud Infrastructure Service Product Dept.)"
<longpeng2@huawei.com>, Paolo Bonzini <pbonzini@redhat.com>,
"Daniel P. Berrange" <berrange@redhat.com>
Cc: chenjiashang@huawei.com,
"Gonglei \(Arei\)" <arei.gonglei@huawei.com>,
Markus Armbruster <armbru@redhat.com>,
QEMU <qemu-devel@nongnu.org>
Subject: Re: A bug of Monitor Chardev ?
Date: Wed, 19 May 2021 20:17:51 +0400 [thread overview]
Message-ID: <CAJ+F1C+4URqrZvAiBk+o-Ei4etL_oBtdPr0cugGmnMaYaZqGyA@mail.gmail.com> (raw)
In-Reply-To: <cd197959-7da0-ee50-1e65-e6b2e7107a86@huawei.com>
[-- Attachment #1: Type: text/plain, Size: 2012 bytes --]
Hi
On Mon, May 17, 2021 at 11:11 AM Longpeng (Mike, Cloud Infrastructure
Service Product Dept.) <longpeng2@huawei.com> wrote:
> 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!
>
>
I see.. I think the simplest would be for the chardev to not be dispatched
in the original thread after monitor_init_qmp(). It looks like this should
translate at least to calling qio_net_listener_set_client_func_full() with
NULL handlers. I can't see where we could fit that in the chardev API.
Perhaps add a new qemu_chr_be_disable_handlers() (until
update_read_handlers is called again to enable them)?
Daniel? Paolo?
--
Marc-André Lureau
[-- Attachment #2: Type: text/html, Size: 2920 bytes --]
next prev parent reply other threads:[~2021-05-19 16:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-17 6:56 A bug of Monitor Chardev ? Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-05-19 16:17 ` Marc-André Lureau [this message]
2021-05-19 16:40 ` Daniel P. Berrangé
2021-05-21 7:25 ` Markus Armbruster
2021-05-21 14:43 ` Peter Xu
2021-05-21 16:33 ` Daniel P. Berrangé
2021-05-21 16:56 ` Daniel P. Berrangé
2021-05-21 16:59 ` Marc-André Lureau
2021-05-21 17:07 ` Daniel P. Berrangé
2021-05-21 17:14 ` Peter Xu
2021-05-25 6:53 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-05-21 17:09 ` Peter Xu
2021-05-21 17:15 ` Daniel P. Berrangé
2021-06-08 14:07 ` Markus Armbruster
2021-06-08 15:37 ` Daniel P. Berrangé
2021-06-09 0:20 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-06-09 10:13 ` Marc-André Lureau
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAJ+F1C+4URqrZvAiBk+o-Ei4etL_oBtdPr0cugGmnMaYaZqGyA@mail.gmail.com \
--to=marcandre.lureau@gmail.com \
--cc=arei.gonglei@huawei.com \
--cc=armbru@redhat.com \
--cc=berrange@redhat.com \
--cc=chenjiashang@huawei.com \
--cc=longpeng2@huawei.com \
--cc=pbonzini@redhat.com \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.