From ed8f16b1786f28d3fb6c6cef79cd4f94deae8857 Mon Sep 17 00:00:00 2001 From: Sergio Lopez Pascual Date: Thu, 28 Nov 2019 11:30:47 +0100 Subject: [PATCH] virtio-scsi: fixed virtio_scsi_ctx_check failed when detaching scsi disk MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Sergio Lopez Pascual Message-id: <20191128113047.253669-2-slp@redhat.com> Patchwork-id: 92747 O-Subject: [RHEL-7.8 qemu-kvm-rhev PATCH v2 1/1] virtio-scsi: fixed virtio_scsi_ctx_check failed when detaching scsi disk Bugzilla: 1764120 RH-Acked-by: Markus Armbruster RH-Acked-by: Max Reitz RH-Acked-by: Maxim Levitsky From: Zhengui li commit a6f230c move blockbackend back to main AioContext on unplug. It set the AioContext of SCSIDevice to the main AioContex, but s->ctx is still the iothread AioContex（if the scsi controller is configure with iothread）. So if there are having in-flight requests during unplug, a failing assertion happend. The bt is below: (gdb) bt #0 0x0000ffff86aacbd0 in raise () from /lib64/libc.so.6 #1 0x0000ffff86aadf7c in abort () from /lib64/libc.so.6 #2 0x0000ffff86aa6124 in __assert_fail_base () from /lib64/libc.so.6 #3 0x0000ffff86aa61a4 in __assert_fail () from /lib64/libc.so.6 #4 0x0000000000529118 in virtio_scsi_ctx_check (d=, s=, s=) at /home/qemu-4.0.0/hw/scsi/virtio-scsi.c:246 #5 0x0000000000529ec4 in virtio_scsi_handle_cmd_req_prepare (s=0x2779ec00, req=0xffff740397d0) at /home/qemu-4.0.0/hw/scsi/virtio-scsi.c:559 #6 0x000000000052a228 in virtio_scsi_handle_cmd_vq (s=0x2779ec00, vq=0xffff7c6d7110) at /home/qemu-4.0.0/hw/scsi/virtio-scsi.c:603 #7 0x000000000052afa8 in virtio_scsi_data_plane_handle_cmd (vdev=, vq=0xffff7c6d7110) at /home/qemu-4.0.0/hw/scsi/virtio-scsi-dataplane.c:59 #8 0x000000000054d94c in virtio_queue_host_notifier_aio_poll (opaque=) at /home/qemu-4.0.0/hw/virtio/virtio.c:2452 assert(blk_get_aio_context(d->conf.blk) == s->ctx) failed. To avoid assertion failed, moving the "if" after qdev_simple_device_unplug_cb. In addition, to avoid another qemu crash below, add aio_disable_external before qdev_simple_device_unplug_cb, which disable the further processing of external clients when doing qdev_simple_device_unplug_cb. (gdb) bt #0 scsi_req_unref (req=0xffff6802c6f0) at hw/scsi/scsi-bus.c:1283 #1 0x00000000005294a4 in virtio_scsi_handle_cmd_req_submit (req=, s=) at /home/qemu-4.0.0/hw/scsi/virtio-scsi.c:589 #2 0x000000000052a2a8 in virtio_scsi_handle_cmd_vq (s=s@entry=0x9c90e90, vq=vq@entry=0xffff7c05f110) at /home/qemu-4.0.0/hw/scsi/virtio-scsi.c:625 #3 0x000000000052afd8 in virtio_scsi_data_plane_handle_cmd (vdev=, vq=0xffff7c05f110) at /home/qemu-4.0.0/hw/scsi/virtio-scsi-dataplane.c:60 #4 0x000000000054d97c in virtio_queue_host_notifier_aio_poll (opaque=) at /home/qemu-4.0.0/hw/virtio/virtio.c:2447 #5 0x00000000009b204c in run_poll_handlers_once (ctx=ctx@entry=0x6efea40, timeout=timeout@entry=0xffff7d7f7308) at util/aio-posix.c:521 #6 0x00000000009b2b64 in run_poll_handlers (ctx=ctx@entry=0x6efea40, max_ns=max_ns@entry=4000, timeout=timeout@entry=0xffff7d7f7308) at util/aio-posix.c:559 #7 0x00000000009b2ca0 in try_poll_mode (ctx=ctx@entry=0x6efea40, timeout=0xffff7d7f7308, timeout@entry=0xffff7d7f7348) at util/aio-posix.c:594 #8 0x00000000009b31b8 in aio_poll (ctx=0x6efea40, blocking=blocking@entry=true) at util/aio-posix.c:636 #9 0x00000000006973cc in iothread_run (opaque=0x6ebd800) at iothread.c:75 #10 0x00000000009b592c in qemu_thread_start (args=0x6efef60) at util/qemu-thread-posix.c:502 #11 0x0000ffff8057f8bc in start_thread () from /lib64/libpthread.so.0 #12 0x0000ffff804e5f8c in thread_start () from /lib64/libc.so.6 (gdb) p bus $1 = (SCSIBus *) 0x0 Signed-off-by: Zhengui li Message-Id: <1563696502-7972-1-git-send-email-lizhengui@huawei.com> Signed-off-by: Paolo Bonzini Message-Id: <1563829520-17525-1-git-send-email-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini (cherry picked from commit 9c5aad84da1c37429d06c193f23a8df6445ed29e) [slp: we need to get a reference to the underlying BDS to be able to switch the context after calling qdev_simple_device_unplug_cb(), as in 2.12 this causes the SCSIDevice to go away immediately] Signed-off-by: Sergio Lopez Signed-off-by: Miroslav Rezanina --- hw/scsi/virtio-scsi.c | 30 ++++++++++++++++++++++++++---- 1 file changed, 26 insertions(+), 4 deletions(-) diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c index 391500b..2bd54b3 100644 --- a/hw/scsi/virtio-scsi.c +++ b/hw/scsi/virtio-scsi.c @@ -20,6 +20,7 @@ #include "qemu/error-report.h" #include "qemu/iov.h" #include "sysemu/block-backend.h" +#include "sysemu/blockdev.h" #include "hw/scsi/scsi.h" #include "scsi/constants.h" #include "hw/virtio/virtio-bus.h" @@ -839,6 +840,9 @@ static void virtio_scsi_hotunplug(HotplugHandler *hotplug_dev, DeviceState *dev, VirtIODevice *vdev = VIRTIO_DEVICE(hotplug_dev); VirtIOSCSI *s = VIRTIO_SCSI(vdev); SCSIDevice *sd = SCSI_DEVICE(dev); + AioContext *ctx = s->ctx ?: qemu_get_aio_context(); + BlockDriverState *bs; + DriveInfo *dinfo; if (virtio_vdev_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) { virtio_scsi_acquire(s); @@ -848,13 +852,31 @@ static void virtio_scsi_hotunplug(HotplugHandler *hotplug_dev, DeviceState *dev, virtio_scsi_release(s); } - if (s->ctx) { + /* + * This SCSIDevice goes away after calling qdev_simple_device_unplug_cb(), + * so get a reference to the underlying BDS here to be able to switch + * its AioContext afterwards. + */ + bs = blk_bs(sd->conf.blk); + + /* + * Drives attached to a legacy device will get auto deleted while + * unplugging the latter, so we don't need to switch their context. + * Get a reference to dinfo here, which is only NULL for non-legacy + * devices, and use it to avoid doing the switch for drives attached + * to legacy devices. + */ + dinfo = blk_legacy_dinfo(sd->conf.blk); + + aio_disable_external(ctx); + qdev_simple_device_unplug_cb(hotplug_dev, dev, errp); + aio_enable_external(ctx); + + if (s->ctx && bs && !dinfo) { virtio_scsi_acquire(s); - blk_set_aio_context(sd->conf.blk, qemu_get_aio_context()); + bdrv_set_aio_context(bs, qemu_get_aio_context()); virtio_scsi_release(s); } - - qdev_simple_device_unplug_cb(hotplug_dev, dev, errp); } static struct SCSIBusInfo virtio_scsi_scsi_info = { -- 1.8.3.1