On 07/22/2010 11:13 PM, Vaidyanathan Srinivasan wrote:
> * Robert Jennings <r...@linux.vnet.ibm.com> [2010-07-22 21:43:44]:
>
>> If a CPU remove is attempted using the 'release' interface on hardware
>> which supports extended cede, the CPU will be put in the INACTIVE state
>> rather than the OFFLINE state due to the default preferred_offline_state
>> in that situation. In the INACTIVE state it will fail to be removed.
>>
>> This patch changes the preferred offline state to OFFLINE when an CPU is
>> in the ONLINE state. After cpu_down() is called in dlpar_offline_cpu()
>> the CPU will be OFFLINE and CPU removal can continue.
>
> Hi Robert,
>
> Thanks for the patch. In dlpar operation, we would offline the CPU
> first using the sysfs online file and then write to the sysfs release
> file to complete the sequence right? The current code in
> dlpar_offline_cpu() would work as long as the cpu is in either
> inactive state or offline state (in case of unsupported platform).
>
> Is the dlpar tools being changed to complete the operation with one
> sysfs write to release file?
The dlpar tools were updated so that a single write to the 'release' file
would offline the cpu and remove it from the system. Given this, I think
Robert's patch should go forward to maintain compatability.
-Nathan
>
>> Signed-off-by: Robert Jennings <r...@linux.vnet.ibm.com>
>>
>> ---
>>
>> diff --git a/arch/powerpc/platforms/pseries/dlpar.c
>> b/arch/powerpc/platforms/pseries/dlpar.c
>> index d71e585..227c1c3 100644
>> --- a/arch/powerpc/platforms/pseries/dlpar.c
>> +++ b/arch/powerpc/platforms/pseries/dlpar.c
>> @@ -463,6 +463,7 @@ static int dlpar_offline_cpu(struct device_node *dn)
>> break;
>>
>> if (get_cpu_current_state(cpu) == CPU_STATE_ONLINE) {
>> + set_preferred_offline_state(cpu,
>> CPU_STATE_OFFLINE);
>> cpu_maps_update_done();
>> rc = cpu_down(cpu);
>> if (rc)
>
> The patch looks good. Will need to test out the various scenarios so
> that the preferred_offline_state do not get flipped before cpu_down()
> is called. This is unlikely, but still we need to validate
> a concurrent sysfs online file write and sysfs release file write.
>
> --Vaidy
>
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