Re: [Qemu-devel] [PATCH v2] throttle-groups: update tg->any_timer_armed[] on detach

[Manos Pitsidianakis <el13635@mail.ntua.gr>]

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On Wed, Sep 20, 2017 at 11:17:40AM +0100, Stefan Hajnoczi wrote:
>Clear tg->any_timer_armed[] when throttling timers are destroyed during
>AioContext attach/detach.  Failure to do so causes throttling to hang
>because we believe the timer is already scheduled!
>
>The following was broken at least since QEMU 2.10.0 with -drive
>iops=100:
>
>  $ dd if=/dev/zero of=/dev/vdb oflag=direct count=1000
>  (qemu) stop
>  (qemu) cont
>  ...I/O is stuck...
>
>Reported-by: Yongxue Hong <yhong@redhat.com>
>Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Reviewed-by: Manos Pitsidianakis <el13635@mail.ntua.gr>


>v2:
> * Use timer_pending(tt->timers[i]) instead of token [Berto]
> * Fix s/destroy/destroyed/ typo [Eric]
>
> block/throttle-groups.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
>diff --git a/block/throttle-groups.c b/block/throttle-groups.c
>index 6ba992c8d7..0a49f3c409 100644
>--- a/block/throttle-groups.c
>+++ b/block/throttle-groups.c
>@@ -592,6 +592,17 @@ void throttle_group_attach_aio_context(ThrottleGroupMember *tgm,
> void throttle_group_detach_aio_context(ThrottleGroupMember *tgm)
> {
>     ThrottleTimers *tt = &tgm->throttle_timers;
>+    ThrottleGroup *tg = container_of(tgm->throttle_state, ThrottleGroup, ts);
>+
>+    qemu_mutex_lock(&tg->lock);
>+    if (timer_pending(tt->timers[0])) {
>+        tg->any_timer_armed[0] = false;
>+    }
>+    if (timer_pending(tt->timers[1])) {
>+        tg->any_timer_armed[1] = false;
>+    }
>+    qemu_mutex_unlock(&tg->lock);
>+
>     throttle_timers_detach_aio_context(tt);
>     tgm->aio_context = NULL;
> }
>-- 
>2.13.5
>
>

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