[PATCH] powerpc/pseries: Don't attempt to acquire drc during memory hot add for assigned lmbs

[Michael Ellerman]

John Allen <jallen at linux.vnet.ibm.com> writes:

> On 08/30/2017 09:35 AM, Nathan Fontenot wrote:
>> On 08/29/2017 09:35 PM, Michael Ellerman wrote:
>>> John Allen <jallen at linux.vnet.ibm.com> writes:
>>>
>>>> Check if an LMB is assigned before attempting to call dlpar_acquire_drc in
>>>> order to avoid any unnecessary rtas calls. This substantially reduces the
>>>> running time of memory hot add on lpars with large amounts of memory.
>>>>
>>>> Signed-off-by: John Allen <jallen at linux.vnet.ibm.com>
>>>> ---
>>>> diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
>>>> index ca9b2f4..95cf2ff 100644
>>>> --- a/arch/powerpc/platforms/pseries/hotplug-memory.c
>>>> +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
>>>> @@ -817,6 +817,9 @@ static int dlpar_memory_add_by_count(u32 lmbs_to_add, struct property *prop)
>>>>  		return -EINVAL;
>>>>
>>>>  	for (i = 0; i < num_lmbs && lmbs_to_add != lmbs_added; i++) {
>>>> +		if (lmbs[i].flags & DRCONF_MEM_ASSIGNED)
>>>> +			continue;
>>>> +
>>>>  		rc = dlpar_acquire_drc(lmbs[i].drc_index);
>>>>  		if (rc)
>>>>  			continue;
>>>
>>> This doesn't build for me, see below. What compiler are you using to
>>> test this?> 
>>>   arch/powerpc/platforms/pseries/hotplug-memory.c: In function 'dlpar_memory':
>>>   arch/powerpc/platforms/pseries/hotplug-memory.c:1081:2: error: 'rc' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>>>     return rc;
>>>     ^
>>>
>> 
>> I don't see this build failure either, looks like its time to update my
>> compiler too.
>
> This also builds for me. I'm using gcc version 4.8.5

OK, that is fairly old.

I generally use 6.x or 7.x, but I see the warning on 5.4.1 also.

cheers