From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55363) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fzNi1-0005sT-3Z for qemu-devel@nongnu.org; Mon, 10 Sep 2018 11:02:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fzNhw-000174-Ee for qemu-devel@nongnu.org; Mon, 10 Sep 2018 11:02:37 -0400 From: Fam Zheng Date: Mon, 10 Sep 2018 22:56:16 +0800 Message-Id: <20180910145616.8598-3-famz@redhat.com> In-Reply-To: <20180910145616.8598-1-famz@redhat.com> References: <20180910145616.8598-1-famz@redhat.com> Subject: [Qemu-devel] [PATCH 2/2] virtio-scsi/virtio-blk: Disable poll handlers when stopping vq handler List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Paolo Bonzini , qemu-block@nongnu.org, Fam Zheng , "Michael S. Tsirkin" , peterx@redhat.com, Stefan Hajnoczi We have this unwanted call stack: > ... > #13 0x00005586602b7793 in virtio_scsi_handle_cmd_vq > #14 0x00005586602b8d66 in virtio_scsi_data_plane_handle_cmd > #15 0x00005586602ddab7 in virtio_queue_notify_aio_vq > #16 0x00005586602dfc9f in virtio_queue_host_notifier_aio_poll > #17 0x00005586607885da in run_poll_handlers_once > #18 0x000055866078880e in try_poll_mode > #19 0x00005586607888eb in aio_poll > #20 0x0000558660784561 in aio_wait_bh_oneshot > #21 0x00005586602b9582 in virtio_scsi_dataplane_stop > #22 0x00005586605a7110 in virtio_bus_stop_ioeventfd > #23 0x00005586605a9426 in virtio_pci_stop_ioeventfd > #24 0x00005586605ab808 in virtio_pci_common_write > #25 0x0000558660242396 in memory_region_write_accessor > #26 0x00005586602425ab in access_with_adjusted_size > #27 0x0000558660245281 in memory_region_dispatch_write > #28 0x00005586601e008e in flatview_write_continue > #29 0x00005586601e01d8 in flatview_write > #30 0x00005586601e04de in address_space_write > #31 0x00005586601e052f in address_space_rw > #32 0x00005586602607f2 in kvm_cpu_exec > #33 0x0000558660227148 in qemu_kvm_cpu_thread_fn > #34 0x000055866078bde7 in qemu_thread_start > #35 0x00007f5784906594 in start_thread > #36 0x00007f5784639e6f in clone Avoid it with the aio_disable_external/aio_enable_external pair, so that no vq poll handlers can be called in aio_wait_bh_oneshot. Signed-off-by: Fam Zheng --- hw/block/dataplane/virtio-blk.c | 2 ++ hw/scsi/virtio-scsi-dataplane.c | 2 ++ 2 files changed, 4 insertions(+) diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index 8c37bd314a..8ab54218c1 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -279,7 +279,9 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev) trace_virtio_blk_data_plane_stop(s); aio_context_acquire(s->ctx); + aio_disable_external(s->ctx); aio_wait_bh_oneshot(s->ctx, virtio_blk_data_plane_stop_bh, s); + aio_enable_external(s->ctx); /* Drain and switch bs back to the QEMU main loop */ blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context()); diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c index b995bab3a2..1452398491 100644 --- a/hw/scsi/virtio-scsi-dataplane.c +++ b/hw/scsi/virtio-scsi-dataplane.c @@ -208,7 +208,9 @@ void virtio_scsi_dataplane_stop(VirtIODevice *vdev) s->dataplane_stopping = true; aio_context_acquire(s->ctx); + aio_disable_external(s->ctx); aio_wait_bh_oneshot(s->ctx, virtio_scsi_dataplane_stop_bh, s); + aio_enable_external(s->ctx); aio_context_release(s->ctx); blk_drain_all(); /* ensure there are no in-flight requests */ -- 2.17.1