From ae4ca7d9cfb0033cf39971f1c59e9a20a80c9bee Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Fri, 17 Nov 2017 11:19:08 +0100 Subject: [PATCH 09/15] throttle-groups: forget timer and schedule next TGM on detach RH-Author: Stefan Hajnoczi Message-id: <20171117111908.8815-10-stefanha@redhat.com> Patchwork-id: 77744 O-Subject: [RHV7.5 qemu-kvm-rhev PATCH 9/9] throttle-groups: forget timer and schedule next TGM on detach Bugzilla: 1492295 RH-Acked-by: John Snow RH-Acked-by: Laurent Vivier RH-Acked-by: Thomas Huth tg->any_timer_armed[] must be cleared when detaching pending timers from the AioContext. Failure to do so leads to hung I/O because it looks like there are still timers pending when in fact they have been removed. Other ThrottleGroupMembers might have requests pending too so it's necessary to schedule the next TGM so it can set a timer. This patch fixes hung I/O when QEMU is launched with drives that are in the same throttling group: (guest)$ dd if=/dev/zero of=/dev/vdb oflag=direct bs=512 & (guest)$ dd if=/dev/zero of=/dev/vdc oflag=direct bs=512 & (qemu) stop (qemu) cont ...I/O is stuck... Signed-off-by: Stefan Hajnoczi Message-id: 20171116112150.27607-1-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi (cherry picked from commit 341e0b5658681f46680024cdbfc998717d85cc35) Signed-off-by: Stefan Hajnoczi Signed-off-by: Miroslav Rezanina --- block/throttle-groups.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/block/throttle-groups.c b/block/throttle-groups.c index 44cc1e6..35c22ac 100644 --- a/block/throttle-groups.c +++ b/block/throttle-groups.c @@ -567,13 +567,25 @@ void throttle_group_attach_aio_context(ThrottleGroupMember *tgm, void throttle_group_detach_aio_context(ThrottleGroupMember *tgm) { + ThrottleGroup *tg = container_of(tgm->throttle_state, ThrottleGroup, ts); ThrottleTimers *tt = &tgm->throttle_timers; + int i; /* Requests must have been drained */ assert(tgm->pending_reqs[0] == 0 && tgm->pending_reqs[1] == 0); assert(qemu_co_queue_empty(&tgm->throttled_reqs[0])); assert(qemu_co_queue_empty(&tgm->throttled_reqs[1])); + /* Kick off next ThrottleGroupMember, if necessary */ + qemu_mutex_lock(&tg->lock); + for (i = 0; i < 2; i++) { + if (timer_pending(tt->timers[i])) { + tg->any_timer_armed[i] = false; + schedule_next_request(tgm, i); + } + } + qemu_mutex_unlock(&tg->lock); + throttle_timers_detach_aio_context(tt); tgm->aio_context = NULL; } -- 1.8.3.1