linux-kernel - Re: [PATCH v2 2/5] powerpc: pseries: vio: match parent nodes with of_find_node_by

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Date:   Thu, 24 Aug 2017 13:08:48 -0500
From:   Rob Herring <robh@...nel.org>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        David Laight <David.Laight@...lab.com>
Subject: Re: [PATCH v2 2/5] powerpc: pseries: vio: match parent nodes with of_find_node_by_path

On Tue, Aug 22, 2017 at 12:12 AM, Michael Ellerman <mpe@...erman.id.au> wrote:
> Rob Herring <robh@...nel.org> writes:
>
>> In preparation to remove the full path from device_node.full_name, use
>> of_find_node_by_path instead of open coding with strcmp.
>>
>> Signed-off-by: Rob Herring <robh@...nel.org>
>> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
>> Cc: Paul Mackerras <paulus@...ba.org>
>> Cc: Michael Ellerman <mpe@...erman.id.au>
>> Cc: linuxppc-dev@...ts.ozlabs.org
>> ---
>> v2:
>> - rebased to linux-next and removed spurious change fro patch 1.
>>
>>  arch/powerpc/platforms/pseries/vio.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/powerpc/platforms/pseries/vio.c b/arch/powerpc/platforms/pseries/vio.c
>> index aa5ca74316fa..5754572deb23 100644
>> --- a/arch/powerpc/platforms/pseries/vio.c
>> +++ b/arch/powerpc/platforms/pseries/vio.c
>> @@ -1357,9 +1357,9 @@ struct vio_dev *vio_register_device_node(struct device_node *of_node)
>>        */
>>       parent_node = of_get_parent(of_node);
>>       if (parent_node) {
>> -             if (!strcmp(parent_node->full_name, "/ibm,platform-facilities"))
>> +             if (parent_node == of_find_node_by_path("/ibm,platform-facilities"))
>>                       family = PFO;
>> -             else if (!strcmp(parent_node->full_name, "/vdevice"))
>> +             else if (parent_node == of_find_node_by_path("/vdevice"))
>>                       family = VDEVICE;
>
> This leaks references to the looked up nodes.
>
> Both these nodes are defined in PAPR (our hypervisor spec), and both of
> them must have a device_type, either "ibm,platform-facilities" or
> "vdevice".
>
> Looking at the commit that added the code I don't see any particular
> reason it used the comparison against full_name, rather than using the
> device_type.
>
> So I'm inclined to do this instead:
>
> diff --git a/arch/powerpc/platforms/pseries/vio.c b/arch/powerpc/platforms/pseries/vio.c
> index 8a47f168476b..f26f906e6021 100644
> --- a/arch/powerpc/platforms/pseries/vio.c
> +++ b/arch/powerpc/platforms/pseries/vio.c
> @@ -1357,9 +1357,9 @@ struct vio_dev *vio_register_device_node(struct device_node *of_node)
>          */
>         parent_node = of_get_parent(of_node);
>         if (parent_node) {
> -               if (!strcmp(parent_node->full_name, "/ibm,platform-facilities"))
> +               if (!strcmp(parent_node->type, "ibm,platform-facilities"))
>                         family = PFO;
> -               else if (!strcmp(parent_node->full_name, "/vdevice"))
> +               else if (!strcmp(parent_node->type, "vdevice"))
>                         family = VDEVICE;
>                 else {
>                         pr_warn("%s: parent(%s) of %s not recognized.\n",
>
>
> I've checked both Qemu and kvmtool add the device_type, and I'm fairly
> confident that PowerVM does too. Anyway I'll test it on all the machines
> I can find.

Okay, do you want me to respin the patch or will you update it with
the above change?

Rob