From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56611) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1afos9-0004pD-LN for qemu-devel@nongnu.org; Tue, 15 Mar 2016 09:19:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1afos3-0000Lb-Jk for qemu-devel@nongnu.org; Tue, 15 Mar 2016 09:18:53 -0400 Received: from e06smtp06.uk.ibm.com ([195.75.94.102]:57715) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1afos3-0000LT-Ai for qemu-devel@nongnu.org; Tue, 15 Mar 2016 09:18:47 -0400 Received: from localhost by e06smtp06.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 15 Mar 2016 13:18:44 -0000 Received: from b06cxnps4075.portsmouth.uk.ibm.com (d06relay12.portsmouth.uk.ibm.com [9.149.109.197]) by d06dlp03.portsmouth.uk.ibm.com (Postfix) with ESMTP id 4B7141B08067 for ; Tue, 15 Mar 2016 13:19:09 +0000 (GMT) Received: from d06av07.portsmouth.uk.ibm.com (d06av07.portsmouth.uk.ibm.com [9.149.37.248]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u2FDIe7g62193762 for ; Tue, 15 Mar 2016 13:18:40 GMT Received: from d06av07.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av07.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u2FDIe9c025172 for ; Tue, 15 Mar 2016 09:18:40 -0400 Date: Tue, 15 Mar 2016 14:18:38 +0100 From: Cornelia Huck Message-ID: <20160315141838.744c2068.cornelia.huck@de.ibm.com> In-Reply-To: <20160315124530.GA10718@ad.usersys.redhat.com> References: <1455470231-5223-1-git-send-email-pbonzini@redhat.com> <1455470231-5223-6-git-send-email-pbonzini@redhat.com> <56E01544.6060305@de.ibm.com> <56E01D3F.1060204@redhat.com> <56E03333.5020601@de.ibm.com> <56E04C9B.7070801@redhat.com> <20160310015154.GD23632@ad.usersys.redhat.com> <56E13849.3060409@de.ibm.com> <56E14101.4030405@de.ibm.com> <56E29DB1.6000200@redhat.com> <20160315124530.GA10718@ad.usersys.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 5/8] virtio-blk: fix "disabled data plane" mode List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng Cc: qemu-devel@nongnu.org, Paolo Bonzini , Christian Borntraeger , Bo Tu On Tue, 15 Mar 2016 20:45:30 +0800 Fam Zheng wrote: > On Fri, 03/11 11:28, Paolo Bonzini wrote: > > But secondarily, I'm thinking of making the logic simpler to understand > > in two ways: > > > > 1) adding a mutex around virtio_blk_data_plane_start/stop. > > > > 2) moving > > > > event_notifier_set(virtio_queue_get_host_notifier(s->vq)); > > virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx, true, true); > > > > to a bottom half (created with aio_bh_new in s->ctx). The bottom half > > takes the mutex, checks again "if (vblk->dataplane_started)" and if it's > > true starts the processing. > > Like this? If it captures your idea, could Bo or Christian help test? > > --- > > From b5b8886693828d498ee184fc7d4e13d8c06cdf39 Mon Sep 17 00:00:00 2001 > From: Fam Zheng > Date: Thu, 10 Mar 2016 10:26:36 +0800 > Subject: [PATCH] virtio-blk dataplane start crash fix > > Suggested-by: Paolo Bonzini > Signed-off-by: Fam Zheng > --- > block.c | 4 +++- > hw/block/dataplane/virtio-blk.c | 39 ++++++++++++++++++++++++++++++++------- > 2 files changed, 35 insertions(+), 8 deletions(-) > > diff --git a/block.c b/block.c > index ba24b8e..e37e8f7 100644 > --- a/block.c > +++ b/block.c > @@ -4093,7 +4093,9 @@ void bdrv_attach_aio_context(BlockDriverState *bs, > > void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) > { > - bdrv_drain(bs); /* ensure there are no in-flight requests */ > + /* ensure there are no in-flight requests */ > + bdrv_drained_begin(bs); > + bdrv_drained_end(bs); > > bdrv_detach_aio_context(bs); > > diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c > index 36f3d2b..6db5c22 100644 > --- a/hw/block/dataplane/virtio-blk.c > +++ b/hw/block/dataplane/virtio-blk.c > @@ -49,6 +49,8 @@ struct VirtIOBlockDataPlane { > > /* Operation blocker on BDS */ > Error *blocker; > + > + QemuMutex start_lock; > }; > > /* Raise an interrupt to signal guest, if necessary */ > @@ -150,6 +152,7 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf, > s = g_new0(VirtIOBlockDataPlane, 1); > s->vdev = vdev; > s->conf = conf; > + qemu_mutex_init(&s->start_lock); > > if (conf->iothread) { > s->iothread = conf->iothread; > @@ -184,15 +187,38 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s) > g_free(s); > } > > +typedef struct { > + VirtIOBlockDataPlane *s; > + QEMUBH *bh; > +} VirtIOBlockStartData; > + > +static void virtio_blk_data_plane_start_bh_cb(void *opaque) > +{ > + VirtIOBlockStartData *data = opaque; > + VirtIOBlockDataPlane *s = data->s; Won't you need to check here whether ->started is still set? > + > + /* Kick right away to begin processing requests already in vring */ > + event_notifier_set(virtio_queue_get_host_notifier(s->vq)); > + > + /* Get this show started by hooking up our callbacks */ > + virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx, true, true); > + > + qemu_bh_delete(data->bh); > + g_free(data); > +} > + > /* Context: QEMU global mutex held */ > void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s) > { > BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev))); > VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus); > VirtIOBlock *vblk = VIRTIO_BLK(s->vdev); > + VirtIOBlockStartData *data; > int r; > > + qemu_mutex_lock(&s->start_lock); > if (vblk->dataplane_started || s->starting) { Do we still need ->starting with the new mutex? > + qemu_mutex_unlock(&s->start_lock); > return; > } > > @@ -221,13 +247,11 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s) > > blk_set_aio_context(s->conf->conf.blk, s->ctx); > > - /* Kick right away to begin processing requests already in vring */ > - event_notifier_set(virtio_queue_get_host_notifier(s->vq)); > - > - /* Get this show started by hooking up our callbacks */ > - aio_context_acquire(s->ctx); > - virtio_queue_aio_set_host_notifier_handler(s->vq, s->ctx, true, true); > - aio_context_release(s->ctx); > + data = g_new(VirtIOBlockStartData, 1); > + data->s = s; > + data->bh = aio_bh_new(s->ctx, virtio_blk_data_plane_start_bh_cb, data); > + qemu_bh_schedule(data->bh); > + qemu_mutex_unlock(&s->start_lock); > return; > > fail_host_notifier: > @@ -236,6 +260,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s) > s->disabled = true; > s->starting = false; > vblk->dataplane_started = true; > + qemu_mutex_unlock(&s->start_lock); > } > > /* Context: QEMU global mutex held */ Do you also need to do something in _stop()?