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Re: [Qemu-devel] [PATCH 2/6] monitor: accept chardev input from iothread
From: |
Peter Xu |
Subject: |
Re: [Qemu-devel] [PATCH 2/6] monitor: accept chardev input from iothread |
Date: |
Wed, 10 Oct 2018 11:45:25 +0800 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
On Tue, Oct 09, 2018 at 05:12:47PM +0400, Marc-André Lureau wrote:
> Chardev backends may not handle safely IO events from concurrent
> threads. Better to wake up the chardev from the monitor IO thread if
> it's being used as the chardev context.
>
> Signed-off-by: Marc-André Lureau <address@hidden>
> ---
> monitor.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/monitor.c b/monitor.c
> index ab60c9f87e..a25514490a 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -4297,6 +4297,13 @@ int monitor_suspend(Monitor *mon)
> return 0;
> }
>
> +static void monitor_accept_input(void *opaque)
> +{
> + Monitor *mon = opaque;
> +
> + qemu_chr_fe_accept_input(&mon->chr);
> +}
> +
> void monitor_resume(Monitor *mon)
> {
> if (monitor_is_hmp_non_interactive(mon)) {
> @@ -4310,13 +4317,14 @@ void monitor_resume(Monitor *mon)
> * let's kick the thread in case it's sleeping.
> */
> if (mon->use_io_thread) {
> - aio_notify(iothread_get_aio_context(mon_iothread));
> +
> aio_bh_schedule_oneshot(iothread_get_aio_context(mon_iothread),
> + monitor_accept_input, mon);
Just to make sure: this will definitely cover the previous
aio_notify(), am I right?
Imho some comment would always be nice here because QMPs with
use_io_thread=true seems special anyway.
> }
> } else {
> assert(mon->rs);
> readline_show_prompt(mon->rs);
> + monitor_accept_input(mon);
> }
> - qemu_chr_fe_accept_input(&mon->chr);
How about the QMP monitors with oob=off? Will it miss the call?
I would consider caching the aio context into Monitor struct when
monitor init, then call aio_bh_schedule_oneshot() always with the
per-monitor aio cache. This could unify the code paths too so we keep
the oob special path as less as possible.
> }
> trace_monitor_suspend(mon, -1);
> }
> --
> 2.19.0.271.gfe8321ec05
>
Regards,
--
Peter Xu
- [Qemu-devel] [PATCH 0/6] monitor: misc fixes, Marc-André Lureau, 2018/10/09
- [Qemu-devel] [PATCH 1/6] monitor: inline ambiguous helper functions, Marc-André Lureau, 2018/10/09
- [Qemu-devel] [PATCH 2/6] monitor: accept chardev input from iothread, Marc-André Lureau, 2018/10/09
- Re: [Qemu-devel] [PATCH 2/6] monitor: accept chardev input from iothread,
Peter Xu <=
- [Qemu-devel] [PATCH 4/6] monitor: check if chardev can switch gcontext for OOB, Marc-André Lureau, 2018/10/09
- [Qemu-devel] [PATCH 3/6] char: add a QEMU_CHAR_FEATURE_GCONTEXT flag, Marc-André Lureau, 2018/10/09
- [Qemu-devel] [PATCH 5/6] monitor: prevent inserting new monitors after cleanup, Marc-André Lureau, 2018/10/09
- [Qemu-devel] [PATCH 6/6] monitor: avoid potential dead-lock when cleaning up, Marc-André Lureau, 2018/10/09