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bh=pXR9qHf9CmmeH9lTSpzRuY3wNjR3PLqQbicL6xK9Yjw=; b=GFkKZ9Dw+Yajy/cBbHB/gDw1QiURdNsJXd1chkCPIoNC+nbWUa3i7jQo0jWMSwYccjjqiu MTazua8hcTdEDtAfxQSIXvkR/MtYSegi/bXp+gLReViNV2YeaLNoDwYw297937Efyp61xR jl9SsLuRBg7f1u85pMMoVRi9noA6Cmw= X-MC-Unique: p2LIVo6dMTa3yzq0fxHxNw-1 From: Paolo Bonzini To: qemu-devel@nongnu.org Subject: [PATCH 04/10] device_core: use drain_call_rcu in in hmp_device_del/qmp_device_add Date: Fri, 25 Sep 2020 13:25:58 -0400 Message-Id: <20200925172604.2142227-5-pbonzini@redhat.com> In-Reply-To: <20200925172604.2142227-1-pbonzini@redhat.com> References: <20200925172604.2142227-1-pbonzini@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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charset="utf-8" From: Maxim Levitsky Soon, a device removal might only happen on RCU callback execution, but to avoid chanding HMP semantics, just drain all pending RCU callbacks Signed-off-by: Maxim Levitsky Suggested-by: Stefan Hajnoczi Reviewed-by: Stefan Hajnoczi Message-Id: <20200913160259.32145-4-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini --- qdev-monitor.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/qdev-monitor.c b/qdev-monitor.c index e9b7228480..c66ba13780 100644 --- a/qdev-monitor.c +++ b/qdev-monitor.c @@ -803,6 +803,18 @@ void qmp_device_add(QDict *qdict, QObject **ret_data, = Error **errp) return; } dev =3D qdev_device_add(opts, errp); + + /* + * Drain all pending RCU callbacks. This is done because + * some bus related operations can delay a device removal + * (in this case this can happen if device is added and then + * removed due to a configuration error) + * to a RCU callback, but user might expect that this interface + * will finish its job completely once qmp command returns result + * to the user + */ + drain_call_rcu(); + if (!dev) { qemu_opts_del(opts); return; @@ -894,6 +906,16 @@ void qmp_device_del(const char *id, Error **errp) } =20 qdev_unplug(dev, errp); + + /* + * Drain all pending RCU callbacks. This is done because + * some bus related operations can delay a device removal + * to a RCU callback, but user might expect that this interface + * will finish its job completely once qmp command returns result + * to the user + */ + + drain_call_rcu(); } } =20 --=20 2.26.2