From: Andrea Arcangeli <aarcange@redhat.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: kvm@vger.kernel.org, Avi Kivity <avi@redhat.com>
Subject: Re: KVM: protect concurrent make_all_cpus_request
Date: Wed, 17 Jun 2009 18:52:02 +0200 [thread overview]
Message-ID: <20090617165202.GD12816@random.random> (raw)
In-Reply-To: <20090617135347.GC14583@amt.cnet>
On Wed, Jun 17, 2009 at 10:53:47AM -0300, Marcelo Tosatti wrote:
>
>
> make_all_cpus_request contains a race condition which can
> trigger false request completed status, as follows:
>
> CPU0 CPU1
>
> if (test_and_set_bit(req,&vcpu->requests))
> .... if (test_and_set_bit(req,&vcpu->requests))
> .. return
> proceed to smp_call_function_many(wait=1)
>
> Use a spinlock to serialize concurrent CPUs.
Agreed, this is the safest...
next prev parent reply other threads:[~2009-06-17 16:52 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-17 13:53 KVM: protect concurrent make_all_cpus_request Marcelo Tosatti
2009-06-17 16:52 ` Andrea Arcangeli [this message]
2009-06-18 8:45 ` Avi Kivity
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