From: Paolo Bonzini <pbonzini@redhat.com>
To: Igor Mammedov <imammedo@redhat.com>,
Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: gleb@kernel.org, mtosatti@redhat.com, stefanha@redhat.com,
mst@redhat.com, rth@twiddle.net, ehabkost@redhat.com,
kvm@vger.kernel.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 2/2] hostmem: detect host backend memory is being used properly
Date: Wed, 13 Jul 2016 12:49:31 +0200 [thread overview]
Message-ID: <e20cd32e-ce44-6c6c-fab1-8f51086e9727@redhat.com> (raw)
In-Reply-To: <20160713093044.356d052d@nial.brq.redhat.com>
On 13/07/2016 09:30, Igor Mammedov wrote:
> I wonder if it could be cleaner to extend QOM API with
>
> object_get_refcount();
>
> and then add
>
> bool hostmem_is_busy()
> {
> return object_get_refcount() > 1;
> }
>
> that would work as not used used hostmem would have ref counter == 1
> and when front-end starts to use it, it calls
> qdev_prop_allow_set_link_before_realize()
> which rises ref counter of backend to 2.
>
> Also see a comment below.
I disagree---there are many reasons why a refcount can be > 1, and given
that we use RCU the release of the reference can be delayed arbitrarily.
Paolo
next prev parent reply other threads:[~2016-07-13 10:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-13 4:18 [Qemu-devel] [PATCH 1/2] hostmem: fix QEMU crash by 'info memdev' Xiao Guangrong
2016-07-13 4:18 ` [Qemu-devel] [PATCH 2/2] hostmem: detect host backend memory is being used properly Xiao Guangrong
2016-07-13 7:30 ` Igor Mammedov
2016-07-13 10:49 ` Paolo Bonzini [this message]
2016-07-13 10:45 ` [Qemu-devel] [PATCH 1/2] hostmem: fix QEMU crash by 'info memdev' Paolo Bonzini
2016-07-13 11:29 ` Markus Armbruster
2016-07-13 11:37 ` Paolo Bonzini
2016-07-15 6:56 ` Xiao Guangrong
2016-07-15 17:16 ` Eric Blake
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