From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49737) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YRPsg-0007oi-UL for qemu-devel@nongnu.org; Fri, 27 Feb 2015 13:43:23 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YRPsd-00022U-GY for qemu-devel@nongnu.org; Fri, 27 Feb 2015 13:43:22 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53791) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YRPsd-00022I-9h for qemu-devel@nongnu.org; Fri, 27 Feb 2015 13:43:19 -0500 Message-ID: <54F0BABF.6010008@redhat.com> Date: Fri, 27 Feb 2015 19:43:11 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <1425057113-26940-1-git-send-email-mreitz@redhat.com> In-Reply-To: <1425057113-26940-1-git-send-email-mreitz@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2] virtio-scsi: Allocate op blocker reason before blocking List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Max Reitz , qemu-devel@nongnu.org Cc: Fam Zheng , Markus Armbruster , Anthony Liguori , "Michael S. Tsirkin" On 27/02/2015 18:11, Max Reitz wrote: > s->blocker is really only used in hw/scsi/virtio-scsi.c; the only places > where it is used in hw/scsi/virtio-scsi-dataplane.c is when it is > allocated and when it is freed. That does not make a whole lot of sense > (and is actually wrong because this leads to s->blocker potentially > being NULL when blk_op_block_all() is called in virtio-scsi.c), so move > the allocation and destruction of s->blocker to the device realization > and unrealization in virtio-scsi.c, respectively. > > Case in point: > > $ echo -e 'eject drv\nquit' | \ > x86_64-softmmu/qemu-system-x86_64 \ > -monitor stdio -machine accel=qtest -display none \ > -object iothread,id=thr -device virtio-scsi-pci,iothread=thr \ > -drive if=none,file=test.qcow2,format=qcow2,id=drv \ > -device scsi-cd,drive=drv > > Without this patch: > > (qemu) eject drv > [1] 10102 done > 10103 segmentation fault (core dumped) > > With this patch: > > (qemu) eject drv > Device 'drv' is busy: block device is in use by data plane > (qemu) quit > > Signed-off-by: Max Reitz > --- > v2: > - Put the reproducer into the commit message [Markus] and modified its > wording to be more fitting of a commit message ("Case in point" > instead of the imperative "Try"). > - As noted by Fam on my bdrv_close_all() series, there can be multiple > block devices per virtio-scsi bus; therefore, it's wrong to delete the > blocker if one of these is unplugged. Instead, just allocate the > blocker with the virtio-scsi device itself and free it when the device > is unrealized. > --- > hw/scsi/virtio-scsi-dataplane.c | 4 ---- > hw/scsi/virtio-scsi.c | 4 ++++ > 2 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c > index 03a1e8c..9b775d4 100644 > --- a/hw/scsi/virtio-scsi-dataplane.c > +++ b/hw/scsi/virtio-scsi-dataplane.c > @@ -211,8 +211,6 @@ void virtio_scsi_dataplane_start(VirtIOSCSI *s) > > s->dataplane_starting = true; > > - assert(!s->blocker); > - error_setg(&s->blocker, "block device is in use by data plane"); > /* Set up guest notifier (irq) */ > rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true); > if (rc != 0) { > @@ -279,8 +277,6 @@ void virtio_scsi_dataplane_stop(VirtIOSCSI *s) > if (!s->dataplane_started || s->dataplane_stopping) { > return; > } > - error_free(s->blocker); > - s->blocker = NULL; > s->dataplane_stopping = true; > assert(s->ctx == iothread_get_aio_context(vs->conf.iothread)); > > diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c > index 9e2c718..9c2a272 100644 > --- a/hw/scsi/virtio-scsi.c > +++ b/hw/scsi/virtio-scsi.c > @@ -904,6 +904,8 @@ static void virtio_scsi_device_realize(DeviceState *dev, Error **errp) > virtio_scsi_save, virtio_scsi_load, s); > s->migration_state_notifier.notify = virtio_scsi_migration_state_changed; > add_migration_state_change_notifier(&s->migration_state_notifier); > + > + error_setg(&s->blocker, "block device is in use by data plane"); > } > > static void virtio_scsi_instance_init(Object *obj) > @@ -929,6 +931,8 @@ static void virtio_scsi_device_unrealize(DeviceState *dev, Error **errp) > { > VirtIOSCSI *s = VIRTIO_SCSI(dev); > > + error_free(s->blocker); > + > unregister_savevm(dev, "virtio-scsi", s); > remove_migration_state_change_notifier(&s->migration_state_notifier); > > Applying, thanks. Paolo