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In-Reply-To: <20190708140858.GC23966@mellanox.com>
From:   "Bernard Metzler" <BMT@zurich.ibm.com>
To:     "Jason Gunthorpe" <jgg@mellanox.com>
Cc:     "Stephen Rothwell" <sfr@canb.auug.org.au>,
        "Doug Ledford" <dledford@redhat.com>,
        "Linux Next Mailing List" <linux-next@vger.kernel.org>,
        "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Date:   Mon, 8 Jul 2019 14:28:13 +0000
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Message-Id: <OF8B5D0A35.3AB4C2D3-ON00258431.004F7CF8-00258431.004F7D00@notes.na.collabserv.com>
Subject: Re:  Re: linux-next: build failure after merge of the rdma tree
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-----"Jason Gunthorpe" <jgg@mellanox.com> wrote: -----

>To: "Stephen Rothwell" <sfr@canb.auug.org.au>, "Bernard Metzler"
><bmt@zurich.ibm.com>
>From: "Jason Gunthorpe" <jgg@mellanox.com>
>Date: 07/08/2019 04:09PM
>Cc: "Doug Ledford" <dledford@redhat.com>, "Linux Next Mailing List"
><linux-next@vger.kernel.org>, "Linux Kernel Mailing List"
><linux-kernel@vger.kernel.org>
>Subject: [EXTERNAL] Re: linux-next: build failure after merge of the
>rdma tree
>
>On Mon, Jul 08, 2019 at 01:03:51PM +1000, Stephen Rothwell wrote:
>> Hi all,
>> 
>> After merging the rdma tree, today's linux-next build (x86_64
>> allmodconfig) failed like this:
>> 
>> In file included from include/asm-generic/percpu.h:7,
>>                  from arch/x86/include/asm/percpu.h:544,
>>                  from arch/x86/include/asm/preempt.h:6,
>>                  from include/linux/preempt.h:78,
>>                  from include/linux/spinlock.h:51,
>>                  from include/linux/seqlock.h:36,
>>                  from include/linux/time.h:6,
>>                  from include/linux/ktime.h:24,
>>                  from include/linux/timer.h:6,
>>                  from include/linux/netdevice.h:24,
>>                  from drivers/infiniband/sw/siw/siw_main.c:8:
>> include/linux/percpu-defs.h:92:33: warning: '__pcpu_unique_use_cnt'
>initialized and declared 'extern'
>>   extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name;  \
>>                                  ^~~~~~~~~~~~~~
>> include/linux/percpu-defs.h:115:2: note: in expansion of macro
>'DEFINE_PER_CPU_SECTION'
>>   DEFINE_PER_CPU_SECTION(type, name, "")
>>   ^~~~~~~~~~~~~~~~~~~~~~
>> drivers/infiniband/sw/siw/siw_main.c:129:8: note: in expansion of
>macro 'DEFINE_PER_CPU'
>>  static DEFINE_PER_CPU(atomic_t, use_cnt = ATOMIC_INIT(0));
>>         ^~~~~~~~~~~~~~
>> include/linux/percpu-defs.h:93:26: error: redefinition of
>'__pcpu_unique_use_cnt'
>>   __PCPU_DUMMY_ATTRS char __pcpu_unique_##name;   \
>>                           ^~~~~~~~~~~~~~
>> include/linux/percpu-defs.h:115:2: note: in expansion of macro
>'DEFINE_PER_CPU_SECTION'
>>   DEFINE_PER_CPU_SECTION(type, name, "")
>>   ^~~~~~~~~~~~~~~~~~~~~~
>> drivers/infiniband/sw/siw/siw_main.c:129:8: note: in expansion of
>macro 'DEFINE_PER_CPU'
>>  static DEFINE_PER_CPU(atomic_t, use_cnt = ATOMIC_INIT(0));
>
>Bernard, 
>
>This looks like the wrong way to use DEFINE_PER_CPU these days. I'm
>not sure why my compiles don't hit it, or why 0-day didn't say
>something
>
>Looking at the other atomic_t PER_CPU users they just rely on
>automatic zero initialization, so this should just be:
>
>  static DEFINE_PER_CPU(atomic_t, use_cnt);
>
>?
>
>Please confirm ASAP.
>

Hi Jason,

Thanks for  bringing this up. Indeed, that explicit
initialization seem to be inappropriate. Can you please
fix that as you suggest?

Thanks very much,
Bernard.