From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: [PATCH v3] xen: domain_update_node_affinity: Bail
 out early if no VCPUs are allocated
Date: Thu, 7 Aug 2014 17:38:30 +0100
Message-ID: <53E3AB86.6080702@citrix.com>
References: <1407428900-1172-1-git-send-email-julien.grall@linaro.org>
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To: Julien Grall <julien.grall@linaro.org>, xen-devel@lists.xenproject.org
Cc: Juergen Gross <jgross@suse.com>, Keir Fraser <keir@xen.org>, ian.campbell@citrix.com, tim@xen.org, Dario Faggioli <dario.faggioli@citrix.com>, Ian Jackson <ian.jackson@eu.citrix.com>, George Dunlap <george.dunlap@citrix.com>, stefano.stabellini@citrix.com, Jan Beulich <jbeulich@suse.com>
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On 07/08/14 17:28, Julien Grall wrote:
> The commit "move domain to cpupool0 before destroying it" make Xen crashes
> when a domain is destroyed with d->vcpus allocated but no VCPU initialized.
>
> Assertion '!cpumask_empty(dom_cpumask)' failed at domain.c:452
> Xen call trace:
>     [<00207bd8>] domain_update_node_affinity+0x10c/0x238 (PC)
>     [<00000004>] 00000004 (LR)
>     [<00226870>] sched_move_domain+0x3cc/0x42c
>     [<0020925c>] domain_kill+0xc8/0x178
>     [<00206a0c>] do_domctl+0xaac/0x15e4
>     [<002529c0>] do_trap_hypervisor+0xc5c/0xf94
>     [<002559f0>] return_from_trap+0/0x4
>
> Bail out early if there is d->VCPU is not allocated or VCPU 0 has not been
> initialized.
>
> Signed-off-by: Julien Grall <julien.grall@linaro.org>
> Cc: George Dunlap <george.dunlap@citrix.com>
> Cc: Dario Faggioli <dario.faggioli@citrix.com>
> Cc: Juergen Gross <jgross@suse.com>
> Cc: Ian Campbell <ian.campbell@citrix.com>
> Cc: Ian Jackson <ian.jackson@eu.citrix.com>
> Cc: Jan Beulich <jbeulich@suse.com>
> Cc: Keir Fraser <keir@xen.org>
> Cc: Tim Deegan <tim@xen.org>
>
> ---
>     This patch should be backported to Xen 4.4
>
>     Changes in v3:
>         - Change commit message
>         - Bail out early rather than modifying the ASSERT
> ---
>  xen/common/domain.c |    3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/xen/common/domain.c b/xen/common/domain.c
> index d7a84cf..f0d93e9 100644
> --- a/xen/common/domain.c
> +++ b/xen/common/domain.c
> @@ -415,6 +415,9 @@ void domain_update_node_affinity(struct domain *d)
>      struct vcpu *v;
>      unsigned int cpu;
>  
> +    if ( !d->vcpu || !d->vcpu[0] )
> +        return;
> +

Please remove the d->vcpu conditional in sched_move_domain(), as it is
entirely redundant with this new check.

~Andrew

>      if ( !zalloc_cpumask_var(&dom_cpumask) )
>          return;
>      if ( !zalloc_cpumask_var(&dom_cpumask_soft) )