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Subject: Re: [PATCH 4.20 193/352] KVM: s390: unregister debug feature on
 failing arch init
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org
Cc:     stable@vger.kernel.org, Michael Mueller <mimu@linux.ibm.com>,
        Cornelia Huck <cohuck@redhat.com>,
        Pierre Morel <pmorel@linux.ibm.com>,
        David Hildenbrand <david@redhat.com>,
        Sasha Levin <sashal@kernel.org>
References: <20190211141846.543045703@linuxfoundation.org>
 <20190211141859.386277295@linuxfoundation.org>
From:   Christian Borntraeger <borntraeger@de.ibm.com>
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Date:   Mon, 11 Feb 2019 15:34:20 +0100
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On 11.02.2019 15:17, Greg Kroah-Hartman wrote:
> 4.20-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> [ Upstream commit 308c3e6673b012beecb96ef04cc65f4a0e7cdd99 ]
> 
> Make sure the debug feature and its allocated resources get
> released upon unsuccessful architecture initialization.
> 
> A related indication of the issue will be reported as kernel
> message.
> 
> Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Message-Id: <20181130143215.69496-2-mimu@linux.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Signed-off-by: Sasha Levin <sashal@kernel.org>

It does not hurt, but I explicitly did not cc stable for this patch as 
kvm_register_device_ops only fails in case of a code error.


> ---
>  arch/s390/kvm/kvm-s390.c | 17 ++++++++++++++---
>  1 file changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index fe24150ff666..d8d8e0788157 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -417,19 +417,30 @@ static void kvm_s390_cpu_feat_init(void)
>  
>  int kvm_arch_init(void *opaque)
>  {
> +	int rc;
> +
>  	kvm_s390_dbf = debug_register("kvm-trace", 32, 1, 7 * sizeof(long));
>  	if (!kvm_s390_dbf)
>  		return -ENOMEM;
>  
>  	if (debug_register_view(kvm_s390_dbf, &debug_sprintf_view)) {
> -		debug_unregister(kvm_s390_dbf);
> -		return -ENOMEM;
> +		rc = -ENOMEM;
> +		goto out_debug_unreg;
>  	}
>  
>  	kvm_s390_cpu_feat_init();
>  
>  	/* Register floating interrupt controller interface. */
> -	return kvm_register_device_ops(&kvm_flic_ops, KVM_DEV_TYPE_FLIC);
> +	rc = kvm_register_device_ops(&kvm_flic_ops, KVM_DEV_TYPE_FLIC);
> +	if (rc) {
> +		pr_err("Failed to register FLIC rc=%d\n", rc);
> +		goto out_debug_unreg;
> +	}
> +	return 0;
> +
> +out_debug_unreg:
> +	debug_unregister(kvm_s390_dbf);
> +	return rc;
>  }
>  
>  void kvm_arch_exit(void)
>