Re: [PATCH v2 3/7] device-core: use RCU for list of childs of a bus

From: Stefan Hajnoczi <stefanha@gmail.com>
To: Maxim Levitsky <mlevitsk@redhat.com>
Cc: "Fam Zheng" <fam@euphon.net>,
	"Daniel P. Berrangé" <berrange@redhat.com>,
	"Eduardo Habkost" <ehabkost@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	qemu-devel@nongnu.org, "Paolo Bonzini" <pbonzini@redhat.com>
Subject: Re: [PATCH v2 3/7] device-core: use RCU for list of childs of a bus
Date: Wed, 27 May 2020 15:45:39 +0100	[thread overview]
Message-ID: <20200527144539.GI29137@stefanha-x1.localdomain> (raw)
In-Reply-To: <20200511160951.8733-4-mlevitsk@redhat.com>

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On Mon, May 11, 2020 at 07:09:47PM +0300, Maxim Levitsky wrote:
> diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
> index d87d989e72..ef47cb2d9c 100644
> --- a/include/hw/qdev-core.h
> +++ b/include/hw/qdev-core.h
> @@ -3,6 +3,8 @@
>  
>  #include "qemu/queue.h"
>  #include "qemu/bitmap.h"
> +#include "qemu/rcu.h"
> +#include "qemu/rcu_queue.h"
>  #include "qom/object.h"
>  #include "hw/hotplug.h"
>  #include "hw/resettable.h"
> @@ -230,6 +232,7 @@ struct BusClass {
>  };
>  
>  typedef struct BusChild {
> +    struct rcu_head rcu;
>      DeviceState *child;
>      int index;
>      QTAILQ_ENTRY(BusChild) sibling;

Please add a doc comment to struct BusState saying the children field is
an RCU QTAILQ and writers must hold the QEMU global mutex.

Stefan

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