| Message ID | 20170919155025.4098-1-stefanha@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | throttle-groups: update tg->any_timer_armed[] on detach | expand |
On 09/19/2017 10:50 AM, Stefan Hajnoczi wrote: > Clear tg->any_timer_armed[] when throttling timers are destroy during s/destroy/destroyed/ > 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> > --- > block/throttle-groups.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > Reviewed-by: Eric Blake <eblake@redhat.com> CC: qemu-stable@nongnu.org
On Tue, Sep 19, 2017 at 11:07:53AM -0500, Eric Blake wrote: > On 09/19/2017 10:50 AM, Stefan Hajnoczi wrote: > > Clear tg->any_timer_armed[] when throttling timers are destroy during > > s/destroy/destroyed/ All your base are belong to us!
On Tue 19 Sep 2017 05:50:25 PM CEST, Stefan Hajnoczi wrote: > Clear tg->any_timer_armed[] when throttling timers are destroy 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> > --- > block/throttle-groups.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/block/throttle-groups.c b/block/throttle-groups.c > index 6ba992c8d7..2bfd03faa0 100644 > --- a/block/throttle-groups.c > +++ b/block/throttle-groups.c > @@ -592,7 +592,20 @@ 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); > + > throttle_timers_detach_aio_context(tt); > + > + /* Forget about these timers, they have been destroyed */ > + qemu_mutex_lock(&tg->lock); > + if (tg->tokens[0] == tgm) { > + tg->any_timer_armed[0] = false; > + } > + if (tg->tokens[1] == tgm) { > + tg->any_timer_armed[1] = false; > + } > + qemu_mutex_unlock(&tg->lock); I think I'd rather check the timers directly using timer_pending(). See https://github.com/qemu/qemu/blob/dbe824cc5/block/throttle-groups.c#L426 Berto
Quoting Stefan Hajnoczi (2017-09-19 10:50:25) > Clear tg->any_timer_armed[] when throttling timers are destroy 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> FYI: this patch has been tagged for stable 2.10.1, but is not yet upstream. Patch freeze for 2.10.1 is September 27th. > --- > block/throttle-groups.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/block/throttle-groups.c b/block/throttle-groups.c > index 6ba992c8d7..2bfd03faa0 100644 > --- a/block/throttle-groups.c > +++ b/block/throttle-groups.c > @@ -592,7 +592,20 @@ 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); > + > throttle_timers_detach_aio_context(tt); > + > + /* Forget about these timers, they have been destroyed */ > + qemu_mutex_lock(&tg->lock); > + if (tg->tokens[0] == tgm) { > + tg->any_timer_armed[0] = false; > + } > + if (tg->tokens[1] == tgm) { > + tg->any_timer_armed[1] = false; > + } > + qemu_mutex_unlock(&tg->lock); > + > tgm->aio_context = NULL; > } > > -- > 2.13.5 > >
diff --git a/block/throttle-groups.c b/block/throttle-groups.c index 6ba992c8d7..2bfd03faa0 100644 --- a/block/throttle-groups.c +++ b/block/throttle-groups.c @@ -592,7 +592,20 @@ 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); + throttle_timers_detach_aio_context(tt); + + /* Forget about these timers, they have been destroyed */ + qemu_mutex_lock(&tg->lock); + if (tg->tokens[0] == tgm) { + tg->any_timer_armed[0] = false; + } + if (tg->tokens[1] == tgm) { + tg->any_timer_armed[1] = false; + } + qemu_mutex_unlock(&tg->lock); + tgm->aio_context = NULL; }
Clear tg->any_timer_armed[] when throttling timers are destroy 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> --- block/throttle-groups.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)