linux-kernel - Re: [PATCH 2/2] powerpc/papr_scm: Fix build failure when CONFIG_PERF

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Date:   Tue, 22 Mar 2022 20:00:46 +0530
From:   kajoljain <kjain@...ux.ibm.com>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Linux NVDIMM <nvdimm@...ts.linux.dev>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux-Next Mailing List <linux-next@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Weiny, Ira" <ira.weiny@...el.com>,
        Vishal L Verma <vishal.l.verma@...el.com>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Santosh Sivaraj <santosh@...six.org>, maddy@...ux.ibm.com,
        rnsastry@...ux.ibm.com,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        atrajeev@...ux.vnet.ibm.com, Vaibhav Jain <vaibhav@...ux.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linux MM <linux-mm@...ck.org>
Subject: Re: [PATCH 2/2] powerpc/papr_scm: Fix build failure when
 CONFIG_PERF_EVENTS is not set



On 3/22/22 07:15, Dan Williams wrote:
> On Mon, Mar 21, 2022 at 2:39 PM Dan Williams <dan.j.williams@...el.com> wrote:
>>
>> On Fri, Mar 18, 2022 at 4:42 AM Kajol Jain <kjain@...ux.ibm.com> wrote:
>>>
>>> The following build failure occures when CONFIG_PERF_EVENTS is not set
>>> as generic pmu functions are not visible in that scenario.
>>>
>>> arch/powerpc/platforms/pseries/papr_scm.c:372:35: error: ‘struct perf_event’ has no member named ‘attr’
>>>          p->nvdimm_events_map[event->attr.config],
>>>                                    ^~
>>> In file included from ./include/linux/list.h:5,
>>>                  from ./include/linux/kobject.h:19,
>>>                  from ./include/linux/of.h:17,
>>>                  from arch/powerpc/platforms/pseries/papr_scm.c:5:
>>> arch/powerpc/platforms/pseries/papr_scm.c: In function ‘papr_scm_pmu_event_init’:
>>> arch/powerpc/platforms/pseries/papr_scm.c:389:49: error: ‘struct perf_event’ has no member named ‘pmu’
>>>   struct nvdimm_pmu *nd_pmu = to_nvdimm_pmu(event->pmu);
>>>                                                  ^~
>>> ./include/linux/container_of.h:18:26: note: in definition of macro ‘container_of’
>>>   void *__mptr = (void *)(ptr);     \
>>>                           ^~~
>>> arch/powerpc/platforms/pseries/papr_scm.c:389:30: note: in expansion of macro ‘to_nvdimm_pmu’
>>>   struct nvdimm_pmu *nd_pmu = to_nvdimm_pmu(event->pmu);
>>>                               ^~~~~~~~~~~~~
>>> In file included from ./include/linux/bits.h:22,
>>>                  from ./include/linux/bitops.h:6,
>>>                  from ./include/linux/of.h:15,
>>>                  from arch/powerpc/platforms/pseries/papr_scm.c:5:
>>>
>>> Fix the build issue by adding check for CONFIG_PERF_EVENTS config option
>>> and disabling the papr_scm perf interface support incase this config
>>> is not set
>>>
>>> Fixes: 4c08d4bbc089 ("powerpc/papr_scm: Add perf interface support") (Commit id
>>> based on linux-next tree)
>>> Signed-off-by: Kajol Jain <kjain@...ux.ibm.com>
>>> ---
>>>  arch/powerpc/platforms/pseries/papr_scm.c | 15 +++++++++++++++
>>
>> This is a bit messier than I would have liked mainly because it dumps
>> a bunch of ifdefery into a C file contrary to coding style, "Wherever
>> possible, don't use preprocessor conditionals (#if, #ifdef) in .c
>> files". I would expect this all to move to an organization like:
>>
>> arch/powerpc/platforms/pseries/papr_scm/main.c
>> arch/powerpc/platforms/pseries/papr_scm/perf.c
>>
>> ...and a new config symbol like:
>>
>> config PAPR_SCM_PERF
>>        depends on PAPR_SCM && PERF_EVENTS
>>        def_bool y
>>
>> ...with wrappers in header files to make everything compile away
>> without any need for main.c to carry an ifdef.
>>
>> Can you turn a patch like that in the next couple days? Otherwise, I
>> think if Linus saw me sending a late breaking compile fix that threw
>> coding style out the window he'd have cause to just drop the pull
>> request entirely.
> 
> Also, please base it on the current state of the libnvdimm-for-next
> branch as -next includes some of the SMART health changes leading to
> at least one conflict.

Ok Dan, I will rebase my changes on top of libnvdimm-for-next branch.

Thanks,
Kajol Jain